Silicate and borosilicate glasses having high refractive index and low density

Abstract

Provided are glasses containing silicon dioxide (Si02) and / or boron oxide (B203) as glass formers and having a refractive index n greater than or equal to 1.7 d (at 587.56 nm) and a density (measured at 25 °C) less than or equal to 4.5 g / cm 3 Optionally, the glasses can be characterized as low optical dispersion, high transmission in the visible and near-ultraviolet (near-UV) range of the electromagnetic spectrum, and / or good glass forming ability.

Description

[0001] This application claims priority under 35 USC § 119(e) to U.S. Provisional Patent Application Serial No. 63 / 076,540, filed September 10, 2020, which is incorporated by reference herein in its entirety. TECHNICAL FIELD

[0002] The present disclosure relates generally to silicoborate and borosilicate glasses having high refractive index and low density. BACKGROUND

[0003] Glasses are used in various optical devices, examples of which include augmented reality devices, virtual reality devices, mixed reality devices, eyeglasses, and the like. Properties required for glasses of this type often include high refractive index and low density. Other required properties can include high transmission in the visible and near-ultraviolet (near-UV) ranges of the electromagnetic spectrum and / or low optical dispersion. It can be challenging to demand a glass that has a combination of these properties that are desired and that can be formed from a composition that has good glass forming ability. For example, generally, as the refractive index of a glass increases, the density tends to increase as well. Materials such as TiO2and Nb2O5are often added to increase the refractive index of a glass without increasing the density of the glass. However, these materials often absorb blue and UV light, which can undesirably decrease the light transmission of the glass in this spectral region. Generally, attempts to increase the refractive index of a glass while maintaining low density and without decreasing transmission in the blue and UV regions of the spectrum can result in a decrease in the glass forming ability of the material. For example, crystallization and / or liquid-liquid phase separation can occur during a cooling process of a glass melt at industry- generally-acceptable cooling rates. Typically, the glass forming ability appears to decrease with increasing amounts of certain materials (e.g., ZrO2, Y2O3, Sc2O3, BeO, etc.).

[0004] Low density high refractive index glasses generally fall into one of two types of chemical systems based on the glass formers employed: (a) silicoborate or borosilicate glasses, in which SiO2and / or B2O3are used as the primary glass former, and (b) phosphate glasses, in which P2O5is used as the primary glass former. The use of glasses that rely on other oxides as the primary glass former (GeO2, TeO2, Bi2O3, and V2O5) can be challenging due to cost, glass forming ability, optical properties, and / or production requirements.

[0005] Phosphate glasses can be characterized as having high refractive index and low density, however, production of phosphate glasses can be challenging due to the risk of volatilization of P2O5 from the melt and / or incompatibility with platinum. In addition, phosphate glasses are typically highly colored and can require an additional bleaching step to provide a glass with the desired transmission properties. In addition to this, phosphate glasses that exhibit high refractive index also tend to have increased optical dispersion.

[0006] Generally, silicate and borosilicate glasses are easier to produce and can exhibit high transmission without a bleaching step. However, compared to phosphate glasses, silicate and borosilicate glasses generally exhibit increased density as the refractive index increases.

[0007] Based on these considerations, there is a need for silicate and borosilicate glasses having high refractive index and low density, optionally combined with high transmission in the visible and near-UV range, low optical dispersion, and / or made from a composition that provides good glass forming ability. SUMMARY

[0008] According to embodiments of the disclosure, the glass comprises: Si02 0.3 to 30.0 wt.%, B203 0.3 to 30.0 wt.%, Nb205 0.3 to 50.0 wt.%, and at least one oxide selected from the group consisting of Zr02, SrO, CaO, Li20, MgO, ZnO, Y203, Ta205, BaO, PbO, Ti02, Gd203, Ge02, K20, La203, and Na20, with the proviso that: Zr02 2.5 to 15.0 wt.%, CaO 0.5 to 25.0 wt.%, Gd203 0.0 to 20.0 wt.%, Y203 0.0 to 10.0 wt.%, Ti02 0.0 to 7.05 wt.%, ZnO 0.0 to 2.0 wt.%, Li20 0.0 to 2.0 wt.%, Ge02 0.0 to 2.0 wt.%, and Ta205 0.0 to 1.0 wt.%. The glass is further defined, in wt.% of oxides, as follows: the sum of (Nb205 + Ti02) is 18.0 to 50.0 wt.%; the sum of (Si02 + B203) is 1.0 to 30.0 wt.%; the sum of (La203 + Gd203) is 0.0 to 40.0 wt.%; the sum of (CaO + SrO + BaO) is 0.2 wt.% or greater; the sum of (PbO + V205) is 0.0 to 1.0 wt.%; the ratio of CaO / (Li20 + Na20 + K20 + MgO + CaO + SrO + BaO + ZnO) is 0.50 or greater; the ratio of (Si02 / (Si02 + B203)) is greater than 0.0 to less than or equal to 0.50; and the ratio of (CaO + SrO + BaO) / (Nb205 + Ti02) is 0.45 or greater. The glass is also substantially free of fluorine.

[0009] According to another embodiment of this disclosure, the glass comprises: SiO2 3.0 mol% to 50.0 mol%, B2O3 18.0 mol% to 33.0 mol%, Nb2O5 1.0 mol% to 30.0 mol%, selected from at least one oxide selected from: WO3, ZrO2, SrO, CaO, Li2O, MgO, ZnO, Y2O3, Ta2O5, BaO, CdO, Bi2O3, PbO, HfO2, TeO2, TiO2, Al2O3, Gd2O3, GeO2, K2O, La2O3, Na2O, MoO3, FeO, Fe2O3, and Yb2O3, provided that: TiO2 is 0.0 mol% to 22.0 mol%; ZnO is 0.0 mol% to 10 mol%. 0.0 mol%; the sum of (SiO2+B2O3) is 3.0 mol% to 50.0 mol%; the sum of (Y2O3+GeO2+Ta2O5+Al2O3+MoO3+PbO+TeO2+FeO+Fe2O3) is 0.0 mol% to 0.5 mol%; the total content of divalent metal oxides RO and the total content of alkali metal oxides Alk2O (RO+Alk2O) is 0.0 mol% to 40.0 mol%; the sum of (Bi2O3+PbO) is 0.0 mol% to 20.0 mol%, and wherein the glass is substantially free of fluorine.

[0010] Furthermore, glass satisfies the following equation (XVI):

[0011] P n –(1.11+0.18*P d ≥0.000(XVI)

[0012] In the formula, P n It is the refractive index parameter, with values ​​ranging from 1.7 to 1.95, and is calculated according to the following equation (XIV):

[0013]

[0014] In the formula, P d The density parameter is calculated based on the following equation (XV):

[0015]

[0016] as well as

[0017] Among them, the glass has a transmittance index T of 0.485 to 0.600. i In the formula, T i The following equation (XII) is used to calculate:

[0018]

[0019] And each oxide listed in equation (XIV), equation (XV) and equation (XII) refers to the amount of the oxide in the glass expressed as mole %.

[0020] According to one or more embodiments of the present disclosure, the glass comprises: SiO2 3.0 mole % or more, B2O3 1.0 mole % or more, Nb2O5 0.5 mole % to 25.0 mole %, a total content of divalent metal oxide RO 3.0 mole % or more, and at least one oxide selected from the group consisting of WO3, ZrO2, SrO, CaO, Li2O, MgO, ZnO, Y2O3, Ta2O5, BaO, CdO, Bi2O3, PbO, HfO2, TeO2, TiO2, Al2O3, Gd2O3, GeO2, K2O, La2O3, Na2O, and Yb2O3, with the proviso that: CaO is 0.0 mole % to 32.0 mole %; Li2O is 0.0 mole % to 7.0 mole %; MgO is 0.0 mole % to 5.0 mole %; Y2O3 is 0.0 mole % to 1.5 mole %; Ta2O5 is 0.0 mole % to 0.5 mole %; BaO is 0.0 mole % to 12.0 mole %; CdO is 0.0 mole % to 10.0 mole %; Bi2O3 is 0.0 mole % to 20.0 mole %; PbO is 0.0 mole % to 1.0 mole %; HfO2 is 0.0 mole % to 5.0 mole %; TeO2 is 0.0 mole % to 5.0 mole %; TiO2 is 0.0 mole % to 18.0 mole %; ZnO is 0.0 mole % to 2.0 mole %; fluorine is 0.0 atom % to 1.0 atom %; a total content of rare earth metal oxide RE2O3 is 0.0 mole % to 23.0 mole %; a sum of (RE2O3 + TiO2 + Nb2O5 + ZrO2 + Bi2O3 + WO3) is 25.0 mole % or more; a sum of (SiO2 + B2O3) is greater than 0.0 mole % to 50.0 mole %; and a sum of (SiO2 + B2O3 + Alk2O + MgO + CaO + SrO + BaO + ZnO) is 4.0 mole % to 69.0 mole %, where Alk2O is a total content of alkali metal oxide. The glass satisfies the following equation (XVII):

[0021] P n – (2.23 - 0.71 * T i ) ≥ 0.000 (XVII)

[0022] where P n is a refractive index parameter having a value of 1.75 to 1.95, and where the refractive index parameter P n is calculated according to the following equation (XIV):

[0023]

[0024] where T i is the transmittance index of the glass calculated according to equation (XII) below:

[0025]

[0026] and

[0027] where the glass has a density parameter P d where the density parameter P d is calculated according to equation (XV) below:

[0028]

[0029] and each oxide listed in equation (XIV), equation (XV) and equation (XII) refers to the amount of the oxide in the glass expressed as mol%.

[0030] These and other aspects, objects, and features of the present disclosure will be understood and appreciated by those of ordinary skill in the art upon study of the following specification, claims, and accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0031] In the drawings:

[0032] Figure 1 shows a plot of the measured refractive index n d (587.56 nm measurement) versus the Abbe number v d for some prior art glasses and some exemplary glasses according to embodiments of the present disclosure;

[0033] Figure 2 shows a plot of the Abbe number v d versus the relative partial dispersion P g-F for some prior art glasses and some exemplary glasses according to embodiments of the present disclosure;

[0034] Figure 3 shows a plot of the measured refractive index n d (587.56 nm measurement) versus the internal transmittance τ int (400 nm wavelength) for some prior art glasses and some exemplary glasses according to embodiments of the present disclosure;

[0035] Figure 4 shows a plot schematically showing the transmittance of a glass sample versus the incident wavelength in the blue and near UV range of the electromagnetic spectrum;

[0036] Figure 5The refractive index n is shown as a measured value for some comparative glass and some exemplary glass according to embodiments of this disclosure. d (Measured at 587.56 nm) and refractive index parameter P n Relationship diagram;

[0037] Figure 6 The following figures show the measured density and density parameter P of some comparative glass and some exemplary glass according to embodiments of this disclosure. d Relationship diagram;

[0038] Figure 7 These are exemplary cooling scheme diagrams of some exemplary glasses according to "15-minute test" conditions and "2.5-minute test" conditions, implemented according to embodiments of this disclosure;

[0039] Figure 8 The density parameter P of some comparative glass and some exemplary glass according to embodiments of this disclosure is shown. d With refractive index parameter P n Relationship diagram;

[0040] Figure 9 The refractive index n is shown as a measured value for some comparative glass and some exemplary glass according to embodiments of this disclosure. d The relationship between (measured at 587.56 nm) and the measured density is shown in the graph.

[0041] Figure 10 The refractive index parameter P of some comparative glass and some exemplary glass according to embodiments of this disclosure is shown. n With the transmittance index T i The relationship diagram represents the blue light transmittance of the glass.

[0042] Figure 11 The refractive index n is shown as a measured value for some comparative glass and some exemplary glass according to embodiments of this disclosure. d (Measured at 587.56 nm) and transmittance index T i The relationship diagram represents the blue light transmittance of the glass.

[0043] Figure 12 The transmission spectra of some comparative glass and exemplary glass according to embodiments of the present disclosure are shown;

[0044] Figure 13 The Abbe number ν of some comparative glass and some exemplary glass according to embodiments of this disclosure is shown. d With relative partial dispersion P g-F The relationship diagram between them represents low density; and

[0045] Figure 14 The Abbe number ν of some comparative glass and some exemplary glass according to embodiments of this disclosure is shown. d With relative partial dispersion P g-F The relationship diagram represents the relationship between a high measured refractive index and a low measured density. Detailed Implementation

[0046] In the following detailed description, exemplary embodiments illustrating specific details are given for illustrative purposes and not for limitation, in order to provide a full understanding of the various principles of this disclosure. However, it will be apparent to those skilled in the art that this disclosure may be practiced in other ways than those detailed herein, after benefiting from this specification. Furthermore, descriptions of well-known devices, methods, and materials may have been omitted so as not to obscure the description of the various principles of the invention. Finally, wherever applicable, the same reference numerals denote the same elements.

[0047] Unless otherwise stated, it is not intended to interpret any method described herein as requiring its steps to be performed in a specific order. Therefore, when a method claim does not actually state that its steps follow a certain order, or does not specifically indicate in the claims or description that the steps are limited to a specific order, it is not intended to imply any particular order. The same applies to any possible unstated basis for interpretation, including but not limited to: the logic regarding the setup of steps or operational procedures; the general meaning derived from grammatical structure or punctuation; and the number or type of embodiments described in the specification.

[0048] As used herein, the term "and / or" when used to list two or more items means that any one of the listed items may be used alone, or any combination of two or more of the listed items may be used. For example, if a composition is described as containing components A, B, and / or C, the composition may contain only A; only B; only C; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B, and C.

[0049] Those skilled in the art, as well as those who utilize and use this disclosure, will make improvements to it. Therefore, it is to be understood that the embodiments shown in the accompanying drawings and described above are merely illustrative and not intended to limit the scope of this disclosure, which is defined by the appended claims and, in accordance with the principles of patent law, is to include the doctrine of equivalents.

[0050] As used herein, the term "about" means amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but can be approximated and / or larger or smaller, reflecting acceptable tolerances, conversion factors, rounding off, measurement error and the like, and other factors that are well-known to those skilled in the art. When used in a context to refer to a value or an endpoint of a range, it is understood that the present disclosure includes the specific value or endpoint referred to. Whether or not an endpoint of a numerical value or a range in the present specification is recited as "about," it is intended that the endpoint be included in both embodiments: one modified with "about" and one not modified with "about." It will also be understood that the endpoint values of each range are meaningful both in relation to the other endpoint value and independently of the other endpoint value.

[0051] The term "formed from" can mean one or more of the following: includes, consists essentially of, or consists of. For example, a component formed from a particular material can include the particular material, consist essentially of the particular material, or consist of the particular material.

[0052] Unless otherwise indicated, all compositional expressions are in mole percent (mol%) of ingredients. Those skilled in the art will appreciate that various melt components (e.g., fluorine, alkali metals, boron, etc.) can be subject to different levels of volatilization during the melting of the components (e.g., as a function of vapor pressure, melt time, and / or melt temperature). As such, the term "about" in relation to such components is intended to include values that differ by about 0.2 mol% from the as-ingredient composition provided herein when measured in the final article. In view of the foregoing, substantial compositional identity between the final article and the ingredient composition is contemplated. In some embodiments, compositions can be expressed in terms of ingredient percentages by weight (wt%) of the oxide, as indicated.

[0053] In the event that fluorine is added to or present in the oxide glass, the molecular representation of the resulting glass composition can be expressed in different ways. In the present disclosure, the fluorine content (when present) as a single item is expressed in atomic percent (atom%), which is determined based on the fraction of fluorine in the sum of all atoms in the glass composition multiplied by the factor 100.

[0054] In the present disclosure, the following approach is used to represent fluorine-containing compositions and concentration ranges. The concentration limits presented for all oxides (e.g., Si02, B203, Na20, etc.) have the following assumptions: the respective cations (e.g., silicon [Si 4+ ], boron [B 3+ ], sodium [Na +) initially exist in the form of the corresponding oxide. When fluorine is present, a portion of the oxygen in the oxides is replaced with fluorine for purposes of calculating the concentration of the components of the composition (i.e., one atom of oxygen is replaced with two atoms of fluorine). It is assumed that the fluorine is present in the form of silicon fluoride (SiF4); thus, the sum of all oxides plus SiF4is assumed to be 100 mole percent or 100 weight percent in all compositions.

[0055] In this document, the terms "free of" and "essentially free of" are used interchangeably to mean the absence of a specified component in a glass composition that was not intentionally added to the glass composition and / or the absence of the specified component. It is understood that a glass composition can contain trace amounts of a specified constituent component as a contaminant or an unspecified amount less than 0.10 mole percent.

[0056] As used herein, the term "unspecified" when used to describe a specified constituent component in a glass composition means a constituent component that was not intentionally added to the glass composition and is present in an amount less than 0.05 mole percent. The unspecified component can have been inadvertently added to the glass composition as an impurity in another constituent component and / or by migration of the unspecified component into the composition during processing of the glass composition.

[0057] The term "glass former" is used herein to refer to a component that, when present in a glass composition alone (i.e., without other components, except unspecified amounts), is capable of forming a glass when the melt is cooled at a rate of no more than about 200°C / minute to about 300°C / minute.

[0058] As used herein, the term "modifier" refers to an oxide of a monovalent or divalent metal, i.e., M20 or MO, where "M" represents the metal. A modifier can be added to a glass composition to change the atomic structure of the melt and the resulting glass. In some embodiments, the modifier can change the coordination number of the cations present in the glass former (e.g., boron in B203), which can result in the formation of a more polymeric atomic network and, as a result, can provide better glass formation.

[0059] As used herein, the term "RO" refers to the total content of divalent metal oxides, the term "R20" refers to the total content of monovalent metal oxides, and the term "Alk20" refers to the total content of alkali metal oxides. The term R20encompasses alkali metal oxides (Alk20) as well as other monovalent metal oxides, such as: Ag20, T120, and Hg20. As discussed below, in the present disclosure, rare earth metal oxides are expressed herein in their standard formula (RE203), where the rare earth metal oxides have an oxidation state of "+3", and thus the rare earth metal oxides are not included in the term RO.

[0060] As used herein, the term "rare earth metal" refers to the metals listed in the lanthanide series of the IUPAC periodic table, plus yttrium and scandium. As used herein, the term "rare earth metal oxide" is used to describe oxides of rare earth metals in different redox states, such as "+3" for lanthanum in La₂O₃, "+4" for cerium in CeO₂, and "+2" for europium in EuO, etc. Generally, the redox state of rare earth metals in oxide glasses can be altered, and specifically, the redox state may change during melting, depending on the batch composition and / or the redox conditions in the furnace where the glass is melted and / or heat-treated (e.g., annealed). Unless otherwise stated, rare earth metal oxides herein are expressed in their standard form, where the rare earth metal oxide has a redox state of "+3". Therefore, when a rare earth metal with a redox state other than "+3" is added to a glass composition batch, the glass composition is recalculated by adding or subtracting some oxygen to maintain the stoichiometry. For example, when CeO2 (cerium in the "+4" redox state) is used as a batch component, the resulting glass composition is recalculated as if 2 moles of CeO2 were equivalent to 1 mole of Ce2O3, and the resulting glass composition exhibits Ce2O3. As used herein, the term "RE" refers to... m O n "RE2O3" is used to refer to the total content of rare earth metal oxides in all redox states, and the term "RE2O3" is used to refer to the total content of rare earth metal oxides in the "+3" redox state.

[0061] The density values ​​of the glass recorded in this article are obtained using measurements with an error of 0.001 g / cm³. 3 The specific gravity of the helium flask was measured at room temperature, and the unit is g / cm³. 3 As used in this paper, density measurements at room temperature (defined as d) RT This refers to measurements taken at 20°C or 25°C, and includes measurements obtained at temperatures ranging from 20°C to 25°C. It should be understood that room temperature may vary between about 20°C and about 25°C; however, for the purposes of this disclosure, density changes within the temperature range of 20°C to 25°C are expected to be less than 0.001 g / cm³. 3 The error is negligible and therefore is not expected to affect the room temperature density measurements recorded in this paper.

[0062] As used herein, the term "low density" means a density less than or equal to 4.5 g / cm³. 3 The term "low density parameter" refers to the density parameter P. d The value is less than or equal to 4.5 g / cm³ 3 .

[0063] As used herein, good glass forming ability refers to the resistance of the melt to devitrification as the material cools. Glass forming ability can be measured by determining the critical cooling rate of the melt. As used herein, the term "critical cooling rate" or "v cr " refers to the minimum cooling rate at which a melt of a given composition forms a glass free of visually observable crystals under an optical microscope at 100x to 500x magnification. The critical cooling rate can be used to measure the glass forming ability of a composition, i.e., the ability of a melt of a given glass composition to form a glass upon cooling. Generally, the lower the critical cooling rate, the better the glass forming ability.

[0064] The term "liquidus temperature" herein refers to the temperature above which a glass composition is completely liquid without crystallization of the glass-forming components. The liquidus temperature values reported herein were obtained by measuring samples using DSC or by isochoric holding of samples encased in platinum foil. For samples measured using DSC, powdered samples were heated to 1250 °C at 10 K / min. The end point of the endothermic event corresponding to the melting of crystals was taken as the liquidus temperature. For the second technique (isochoric holding), glass blocks (about 1 cm 3 ) were encased in platinum foil (to avoid volatilization) and placed in a furnace at a given temperature for 17 hours. The glass blocks were then observed with an optical microscope to check for crystals.

[0065] Unless otherwise indicated, the refractive index values reported herein were measured at room temperature (about 25 °C). The refractive index values of the glass samples were measured using a Metricon Model 2010 Prism Coupler Refractometer with an error of about ±0.0002. The refractive index of the glass samples was measured at two or more wavelengths of about 406 nm, 473 nm, 532 nm, 633 nm, 828 nm, and 1064 nm using the Metricon. The correlations measured characterized the dispersion, which was then fitted with Cauchy's law equation or the Sellmeier equation to enable calculation of the refractive index of the sample at a given wavelength of interest between the measured wavelengths. In this document, the term "refractive index n d " refers to the refractive index calculated at a wavelength of 587.56 nm as described above, which corresponds to the helium d-line wavelength. In this document, the term "refractive index n C " refers to the refractive index calculated at a wavelength of 656.3 nm as described above. In this document, the term "refractive index n F " refers to the refractive index calculated at a wavelength of 486.1 nm as described above. In this document, the term "refractive index n g " refers to the refractive index calculated at a wavelength of 435.8 nm as described above.

[0066] As used herein, unless otherwise indicated, the term "high refractive index" or "high refractive indices" means a glass having a refractive index value of at least 1.70 or greater. In the case of the present disclosure, the term "high refractive index" or "high refractive indices" means a glass having a refractive index value of at least 1.75 or greater, at least 1.80 or greater, or at least 1.85 or greater. As used herein, the term "high Abbe number" means a glass having an Abbe number P n of at least 1.70 or greater.

[0067] The terms "dispersion" and "optical dispersion" are used interchangeably to describe the difference or ratio of the refractive indices of a glass sample at predetermined wavelengths. One numerical measure of optical dispersion as reported herein is the Abbe number, which can be calculated by the following equation: ν x = (n x - 1) / (n F - n C ), where "x" in the present disclosure refers to one of the commonly used wavelengths (e.g., 587.56 nm [d-line] or 589.3 nm [D-line]), n x is the refractive index at this wavelength, and n F and n C are the refractive indices at wavelengths 486.1 nm (F-line) and 656.3 nm (C-line), respectively. The numerical difference between ν d and ν D is very slight, most often within ±0.1% to ±0.2%. As reported herein, the dispersion of a glass sample is represented by the Abbe number (ν d ), which characterizes the relationship between the refractive indices of a sample at three different wavelengths according to the following equation (I):

[0068] ν d = (n d - 1) / (n F - n C ) (I)

[0069] where n d is the refractive index calculated at 587.56 nm (d-line), n F is the refractive index calculated at 486.1 nm, and n C is the refractive index calculated at 656.3 nm. A higher Abbe number corresponds to a lower optical dispersion.

[0070] The Abbe number corresponding to "high dispersion" or "low dispersion" can vary depending on the refractive index used to calculate the Abbe number. In some cases, the Abbe number corresponding to "low dispersion" for high-refractive-index glass may be lower than that for low-refractive-index glass. In other words, as the calculated refractive index value increases, the Abbe number corresponding to low dispersion decreases.

[0071] As used in this paper, the relative partial dispersion P can be determined according to the following equation (II). g-F :

[0072] P g-F =(n g -n F ) / (n F -n C (II)

[0073] In the formula, n g The refractive index is calculated at 435.8 nm, n F The refractive index is calculated at 486.1 nm, and n C It is the refractive index calculated at 656.3 nm.

[0074] Unless otherwise stated, as used herein, the term "internal transmittance" refers to the transmittance through a glass sample after adjusting for Fresnel loss. The term "transmittance" is used to describe a transmittance value without considering Fresnel loss. For 2 mm thick samples, the transmittance of the glass samples was measured using a Carry 5000 spectrometer (1 nm resolution, using an integrating sphere) at wavelengths from 250 nm to 2500 nm. The internal transmittance value of a 10 mm thick sample was calculated between 375 nm and 1175 nm using the measured refractive index and the measured raw transmittance.

[0075] As used herein, the term "blue light" refers to blue and ultraviolet light corresponding to wavelengths from approximately 330 nm to approximately 480 nm. The term "internal transmittance of blue light" refers to the transmittance of blue light after correcting for Fresnel loss. The term "transmittance of blue light" refers to the transmittance of blue light without taking Fresnel loss into account.

[0076] Embodiments of the present disclosure generally relate to silicoborate and borosilicate glasses having high refractive index and low density. In some embodiments, the glasses can also be characterized by low optical dispersion and / or high transmission in the visible and near-ultraviolet (near-UV) range of the electromagnetic spectrum. Glasses of the present disclosure can contain silica (Si02) and boron oxide (B203) as glass formers, as well as one or more additional modifiers and / or index enhancers, examples of which include Zr02, La203, Nb205, Ti02, and Gd203. In some embodiments, the glasses can include lower amounts of Ti02and higher amounts of La203, Zr02, and / or other low-absorbing oxide species. According to some embodiments, the glasses can include oxides such as Si02, B203, CaO, La203, Zr02, Ti02, and / or Nb205in proportions that provide a batch composition with acceptable glass forming ability.

[0077] According to embodiments of the present disclosure, the glasses described herein include silica (Si02) and / or boron oxide (B203) as glass formers. Increasing the amount of glass-forming oxides (e.g., Si02and B203) results in a corresponding increase in viscosity values at a given temperature, which can protect the melt from crystallization during cooling and thus provide a glass with a lower critical cooling rate. In some embodiments, the glasses of the present disclosure can include both Si02and B203to provide a glass with a desired critical cooling rate, i.e., a desired degree of glass forming ability.

[0078] According to one embodiment, the amount of Si02 present in the glass can be greater than 3.0 mol%, greater than 4.0 mol%, greater than 5.0 mol%, greater than 10.0 mol%, greater than 15.0 mol%, greater than 20.0 mol%, greater than 25.0 mol%, greater than 30.0 mol%, greater than 35.0 mol%, or greater than 40.0 mol%. In some embodiments, the amount of Si02 present in the glass can be from 3.0 mol% to 50.0 mol%.For example, the SiO2can be present in an amount of: 3.0 to 50.0 mole %, 4.0 to 50.0 mole %, 5.0 to 50.0 mole %, 10.0 to 50.0 mole %, 15.0 to 50.0 mole %, 20.0 to 50.0 mole %, 24.0 to 50.0 mole %, 29.0 to 50.0 mole %, 35.0 to 50.0 mole %, 40.0 to 50.0 mole %, 45.0 to 50.0 mole %, 3.0 to 45.0 mole %, 4.0 to 45.0 mole %, 5.0 to 45.0 mole %, 10.0 to 45.0 mole %, 15.0 to 45.0 mole %, 20.0 to 45.0 mole %, 24.0 to 45.0 mole %, 29.0 to 45.0 mole %, 35.0 to 45.0 mole %, 40.0 to 45.0 mole %, 3.0 to 40.0 mole %, 4.0 to 40.0 mole %, 5.0 to 40.0 mole %, 10.0 to 40.0 mole %, 15.0 to 40.0 mole %, 20.0 to 40.0 mole %, 24.0 to 40.0 mole %, 29.0 to 40.0 mole %, 35.0 to 40.0 mole %, 3.0 to 35.0 mole %, 4.0 to 35.0 mole %, 5.0 to 35.0 mole %, 10.0 to 35.0 mole %, 15.0 to 35.0 mole %, 20.0 to 35.0 mole %, 24.0 to 35.0 mole %, 29.0 to 35.0 mole %, 3.0 to 29.0 mole %, 4.0 to 29.0 mole %, 5.0 to 29.0 mole %, 10.0 to 29.0 mole %, 15.0 to 29.0 mole %, 20.0 to 29.0 mole %, 24.0 to 29.0 mole %, 3.0 to 24.0 mole %, 4.0 to 24.0 mole %, 5.0 to 24.0 mole %, 10.0 to 24.0 mole %, 15.0 to 24.0 mole %, 20.0 to 24.0 mole %, 3.0 to 20.0 mole %, 4.0 to 20.0 mole %, 5.0 to 20.0 mole %, 10.0 to 20.0 mole %, or 15.0 to 20.0 mole %.

[0079] In some embodiments, the amount of Si02present in the glass can be 0.3 wt.% to 30.0 wt.%. For example, the amount of Si02present can be: 0.3 wt.% to 30.0 wt.%, 1.0 wt.% to 30.0 wt.%, 5.0 wt.% to 30.0 wt.%, 8.0 wt.% to 30.0 wt.%, 10.0 wt.% to 30.0 wt.%, 15.0 wt.% to 30.0 wt.%, 20.0 wt.% to 30.0 wt.%, 25.0 wt.% to 30.0 wt.%, 0.3 wt.% to 25.0 wt.%, 1.0 wt.% to 25.0 wt.%, 5.0 wt.% to 25.0 wt.%, 8.0 wt.% to 25.0 wt.%, 10.0 wt.% to 25.0 wt.%, 15.0 wt.% to 25.0 wt.%, 20.0 wt.% to 25.0 wt.%, 0.3 wt.% to 20.0 wt.%, 1.0 wt.% to 20.0 wt.%, 5.0 wt.% to 20.0 wt.%, 8.0 wt.% to 20.0 wt.%, 10.0 wt.% to 20.0 wt.%, 15.0 wt.% to 20.0 wt.%, 0.3 wt.% to 15.0 wt.%, 1.0 wt.% to 15.0 wt.%, 5.0 wt.% to 15.0 wt.%, 8.0 wt.% to 15.0 wt.%, 10.0 wt.% to 15.0 wt.%, 0.3 wt.% to 10.0 wt.%, 1.0 wt.% to 10.0 wt.%, or 5.0 wt.% to 10.0 wt.%.

[0080] According to one embodiment of the disclosure, the amount of B2O3present in the glass can be 1.0 mol% or more. For example, the amount of B2O3present can be: 1.0 mol% or more, 3.0 mol% or more, 5.0 mol% or more, 10.0 mol% or more, 15.0 mol% or more, or 20.0 mol% or more. In some embodiments, the amount of B2O3present in the glass can be 1.0 mol% to 35.0 mol%. For example, the amount of B2O3present in the glass can be: 1.0 mol% to 35.0 mol%, 1.0 mol% to 33.0 mol%, 1.0 mol% to 31.0 mol%, 1.0 mol% to 30.0 mol%, 1.0 mol% to 25.0 mol%, 1.0 mol% to 20.0 mol%, 1.0 mol% to 19.0 mol%, 1.0 mol% to 18.0 mol%, 1.0 mol% to 15.0 mol%, 1.0 mol% to 10.0 mol%, 1.0 mol% to 9.0 mol%, 5.0 mol% to 35.0 mol%, 5.0 mol% to 33.0 mol%, 5.0 mol% to 31.0 mol%, 5.0 mol% to 30.0 mol%, 5.0 mol% to 25 mol%, 5.0 mol% to 20.0 mol%, 5.0 mol% to 19.0 mol%, 5.0 mol% to 18.0 mol%, 5.0 mol% to 15.0 mol%, 5.0 mol% to 10.0 mol%, 5.0 mol% to 9.0 mol%, 9.0 mol% to 35.0 mol%, 9.0 mol% to 33.0 mol%, 9.0 mol% to 31.0 mol%, 9.0 mol% to 30.0 mol%, 9.0 mol% to 25.0 mol%, 9.0 mol% to 20.0 mol%, 9.0 mol% to 19.0 mol%, 9.0 mol% to 18.0 mol%, 9.0 mol% to 15.0 mol%, 9.0 mol% to 10.0 mol%, 10.0 mol% to 35.0 mol%, 10.0 mol% to 33.0 mol%, 10.0 mol% to 31.0 mol%, 10.0 mol% to 30.0 mol%, 10.0 mol% to 25.0 mol%, 10.0 mol% to 20.0 mol%, 10.0 mol% to 19.0 mol%, 10.0 mol% to 18.0 mol%, 10.0 mol% to 15.0 mol%, 15.0 mol% to 35.0 mol%, 15.0 mol% to 33.0 mol%, 15.0 mol% to 31.0 mol%, 15.0 mol% to 30.0 mol%, 15.0 mol% to 25.0 mol%, 15.0 mol% to 20.0 mol%, 15.0 mol% to 19.0 mol%, 15.0 mol% to 18.0 mol%, 18.0 mol% to 35.0 mol%, 18.0 mol% to 33.0 mol%, 18.0 mol% to 31.0 mol%, 18.0 mol% to 30.0 mol%, 18.0 mol% to 25 mol%, 18.0 mol% to 20.0 mol%, 18.0 mol% to 19.0 mol%, 19.0 mol% to 35.0 mol%, 19.0 mol% to 33.0 mol%, 19.0 mol% to 31.0 mol%, 19.0 mol% to 30.0 mol%, 19.0 mol% to 25.0 mol%, 19.0 mol% to 20.0 mol%, 20.0 mol% to 35.0 mol%, 20.0 mol% to 33.0 mol%, 20.0 mol% to 31.0 mol%, or 20.0 mol% to 30.0 mol%.

[0081] In some embodiments, the amount of B2O3 present in the glass can be 0.3 wt% to 30.0 wt%. For example, the amount of B2O3 present can be: 0.3 wt% to 30.0 wt%, 1.0 wt% to 30.0 wt%, 5.0 wt% to 30.0 wt%, 8.0 wt% to 30.0 wt%, 10.0 wt% to 30.0 wt%, 15.0 wt% to 30.0 wt%, 20.0 wt% to 30.0 wt%, 25.0 wt% to 30.0 wt%, 0.3 wt% to 25.0 wt%, 1.0 wt% to 25.0 wt%, 5.0 wt% to 25.0 wt%, 8.0 wt% to 25.0 wt%, 10.0 wt% to 25.0 wt%, 15.0 wt% to 25.0 wt%, 20.0 wt% to 25.0 wt%, 0.3 wt% to 20.0 wt%, 1.0 wt% to 20.0 wt%, 5.0 wt% to 20.0 wt%, 8.0 wt% to 20.0 wt%, 10.0 wt% to 20.0 wt%, 15.0 wt% to 20.0 wt%, 0.3 wt% to 15.0 wt%, 1.0 wt% to 15.0 wt%, 5.0 wt% to 15.0 wt%, 8.0 wt% to 15.0 wt%, 10.0 wt% to 15.0 wt%, 0.3 wt% to 10.0 wt%, 1.0 wt% to 10.0 wt%, or 5.0 wt% to 10.0 wt%.

[0082] However, the combination of Si02and B203may result in a decrease in the refractive index, which can make it more challenging to provide a glass with the desired high refractive index. Accordingly, in some embodiments, the total amount of Si02and B203in the glass (Si02+ B203) can be limited. According to one embodiment, the glass of the present disclosure comprises a total amount of Si02and B203(Si02+ B203) of greater than 0.0 mole% to 50.0 mole%. For example, the sum of (Si02+ B203) in the glass can be: greater than 0.0 mole% to 50.0 mole%, 1.0 mole% to 50.0 mole%, 3.0 mole% to 50.0 mole%, 5.0 mole% to 50.0 mole%, 10.0 mole% to 50.0 mole%, 15.0 mole% to 50.0 mole%, 20.0 mole% to 50.0 mole%, 25.0 mole% to 50.0 mole%, 30.0 mole% to 50.0 mole%, 35.0 mole% to 50.0 mole%, 40.0 mole% to 50.0 mole%, 45.0 mole% to 50.0 mole%, greater than 0.0 mole% to 46.0 mole%, 1.0 mole% to 46.0 mole%, 3.0 mole% to 46.0 mole%, 5.0 mole% to 46.0 mole%, 10.0 mole% to 46.0 mole%, 15.0 mole% to 46.0 mole%, 20.0 mole% to 46.0 mole%, 25.0 mole% to 46.0 mole%, 30.0 mole% to 46.0 mole%, 32.0 mole% to 44.0 mole%, 35.0 mole% to 46.0 mole%, 40.0 mole% to 46.0 mole%, greater than 0.0 mole% to 40.0 mole%, 1.0 mole% to 40.0 mole%, 3.0 mole% to 40.0 mole%, 5.0 mole% to 40.0 mole%, 10.0 mole% to 40.0 mole%, 15.0 mole% to 40.0 mole%, 20.0 mole% to 40.0 mole%, 25.0 mole% to 40.0 mole%, 30.0 mole% to 40.0 mole%, 35.0 mole% to 40.0 mole%, greater than 0.0 mole% to 35.0 mole%, 1.0 mole% to 35.0 mole%, 3.0 mole% to 35.0 mole%, 5.0 mole% to 35.0 mole%, 10.0 mole% to 35.0 mole%, 15.0 mole% to 35.0 mole%, 20.0 mole% to 35.0 mole%, 25.0 mole% to 35.0 mole%, 30.0 mole% to 35.0 mole%, greater than 0.0 mole% to 30.0 mole%, 1.0 mole% to 30.0 mole%, 3.0 mole% to 30.0 mole%, 5.0 mole% to 30.0 mole%, 10.0 mole% to 30.0 mole%, 15.0 mole% to 30.0 mole%, 20.0 mole% to 30.0 mole%, 25.0 mole% to 30.0 mole%, greater than 0.0 mole% to 25.0 mole%, 1.0 mole% to 25.0 mole%, 3.0 mole% to 25.0 mole%, 5.0 mole% to 25.0 mole%, 10.0 mole% to 25.0 mole%, 15.0 mole% to 25.0 mole%, 20.0 mole% to 25.0 mole%, 25.0 mole% to 25.0 mole%, greater than 0.0 mole% to 20.0 mole%, 1.0 mole% to 20.0 mole%, 3.0 mole% to 20.0 mole%, 5.0 mole% to 20.0 mole%, 10.0 mole% to 20.0 mole%, 15.0 mole% to 20.0 mole%, 20.0 mole% to 20.0 mole%, greater than 0.0 mole% to 15.0 mole%, 1.0 mole% to 15.0 mole%, 3.0 mole% to 15.0 mole%, 5.0 mole% to 15.0 mole%, 10.0 mole% to 15.0 mole%, 15.0 mole% to 15.0 mole%, greater than 0.0 mole% to 10.0 mole%, 1.0 mole% to 10.0 mole%, 3.0 mole% to 10.0 mole%, 5.0 mole% to 10.0 mole%, 10.0 mole% to 10.0 mole%, greater than 0.0 mole% to 5.0 mole%, 1.0 mole% to 5.0 mole%, 3.0 mole% to 5.0 mole%, 5.0 mole% to 5.0 mole%, or greater than 0.0 mole% to 3.0 mole%.0.0 mol% to 25.0 mol%, 10.0 mol% to 25.0 mol%, 15.0 mol% to 25.0 mol%, 20.0 mol% to 25.0 mol%, greater than 0.0 mol% to 20.0 mol%, 1.0 mol% to 20.0 mol%, 3.0 mol% to 20.0 mol%, 5.0 mol% to 20.0 mol%, 10.0 mol% to 20.0 mol%, 15.0 mol% to 20.0 mol%, greater than 0.0 mol% to 15.0 mol%, 1.0 mol% to 15.0 mol%, 3.0 mol% to 15.0 mol%, 5.0 mol% to 15.0 mol%, 10.0 mol% to 15.0 mol%, greater than 0.0 mol% to 10.0 mol%, 1.0 mol% to 10.0 mol%, 3.0 mol% to 10.0 mol%, 5.0 mol% to 10.0 mol%, greater than 0.0 mol% to 5.0 mol%, 1.0 mol% to 5.0 mol%, 3.0 mol% to 5.0 mol%, greater than 0.0 mol% to 3.0 mol%, or 1.0 mol% to 3.0 mol%.

[0083] In some embodiments, the ratio of Si02to B203(Si02 / B203) is 0.40 to 0.70 in weight percent oxide. For example, the ratio of Si02to B203(Si02 / B203) can be, in weight percent oxide: 0.40 to 0.70, 0.40 to 0.65, 0.40 to 0.60, 0.40 to 0.55, 0.40 to 0.50, 0.45 to 0.70, 0.45 to 0.65, 0.45 to 0.60, 0.45 to 0.55, 0.45 to 0.50, 0.50 to 0.70, 0.50 to 0.65, 0.50 to 0.60, 0.50 to 0.55, 0.55 to 0.70, 0.55 to 0.65, 0.55 to 0.60, or 0.60 to 0.70.

[0084] In some embodiments, the sum of Si02and B203(in wt. %) (Si02+ B203) is 1.0 wt.% to 30.0 wt.%. For example, the sum of (Si02+ B203) in wt.% is: 1.0 wt.% to 30.0 wt.%, 5.0 wt.% to 30.0 wt.%, 8.0 wt.% to 30.0 wt.%, 10.0 wt.% to 30.0 wt.%, 15.0 wt.% to 30.0 wt.%, 20.0 wt.% to 30.0 wt.%, 25.0 wt.% to 30.0 wt.%, 1.0 wt.% to 25.0 wt.%, 5.0 wt.% to 25.0 wt.%, 8.0 wt.% to 25.0 wt.%, 10.0 wt.% to 25.0 wt.%, 15.0 wt.% to 25.0 wt.%, 20.0 wt.% to 25.0 wt.%, 1.0 wt.% to 20.0 wt.%, 5.0 wt.% to 20.0 wt.%, 8.0 wt.% to 20.0 wt.%, 10.0 wt.% to 20.0 wt.%, 15.0 wt.% to 20.0 wt.%, 1.0 wt.% to 15.0 wt.%, 5.0 wt.% to 15.0 wt.%, 8.0 wt.% to 15.0 wt.%, 10.0 wt.% to 15.0 wt.%, 1.0 wt.% to 10.0 wt.%, or 5.0 wt.% to 10.0 wt.%.

[0085] In some other embodiments, the ratio of (Si02 / (Si02+ B203)) expressed in wt.% is greater than 0.0 to less than or equal to 0.50. For example, the ratio of (Si02 / (Si02+ B203)) expressed in wt.% is: greater than 0.0 to less than or equal to 0.50, greater than 0.0 to less than or equal to 0.40, greater than 0.0 to less than or equal to 0.30, greater than 0.0 to less than or equal to 0.20, greater than 0.0 to less than or equal to 0.10, greater than 0.0 to less than or equal to 0.05, greater than or equal to 0.05 to less than or equal to 0.50, greater than or equal to 0.05 to less than or equal to 0.40, greater than or equal to 0.05 to less than or equal to 0.30, greater than or equal to 0.05 to less than or equal to 0.20, greater than or equal to 0.05 to less than or equal to 0.10, greater than or equal to 0.10 to less than or equal to 0.50, greater than or equal to 0.10 to less than or equal to 0.40, greater than or equal to 0.10 to less than or equal to 0.30, greater than or equal to 0.10 to less than or equal to 0.20, greater than or equal to 0.20 to less than or equal to 0.50, greater than or equal to 0.20 to less than or equal to 0.40, greater than or equal to 0.20 to less than or equal to 0.30, greater than or equal to 0.30 to less than or equal to 0.50, or greater than or equal to 0.30 to less than or equal to 0.40.

[0086] In some embodiments, it was discovered that a concentration of Si02less than 3.0 mole% and a concentration of B203less than 1.0 mole% resulted in glasses with lower glass formability, lower formability, and reduced chemical durability, which can be unsuitable for many industrial applications. Conversely, when the concentrations of Si02and B203were too high, it can be difficult to achieve the desired high refractive index. Thus, in some embodiments, the glasses of the present disclosure comprise Si02in an amount of 3.0 mole% to 50.0 mole% and B203in an amount greater than or equal to 1.0 mole%, the amounts being such that the sum of Si02and B203(Si02+B203) is less than or equal to 50.0 mole%. In some embodiments, the amount of B203is further limited to 18.0 mole% to 33.0 mole%.

[0087] According to embodiments of the present disclosure, the glass can comprise one or more refractive index enhancers added to increase the refractive index of the glass. Examples of refractive index enhancers that can be used in the glasses of the present disclosure include titanium oxide (Ti02), niobium oxide (Nb205), zirconium oxide (Zr02), and other rare earth metal oxides.

[0088] Titanium oxide (Ti02) is generally expected to increase the refractive index of the glass, in combination with achieving low density and / or acceptable low dispersion. In some examples, titanium oxide can produce a yellow or brown colored glass, which can be addressed by bleaching, such as by oxidizing state melting and / or annealing and / or by adding one or more oxidizing agents to the glass batch, examples of which include Ce02, As205, and Mn203, among others. In some cases, too high of an amount of titanium oxide can result in crystallization of refractory species (e.g., rutile (Ti02), sphene (CaTiSi05), and titanium niobate (e.g., Ti2Nb 10 O 29 ) among others), which can result in an increase in the liquidus temperature of the glass, and thus can reduce the glass formability of the melt. Furthermore, at high concentrations, titanium oxide can result in liquid-liquid phase separation of the melt, which can result in a loss of transmission of the glass. According to embodiments of the present disclosure, these difficulties can be addressed by limiting the amount of Ti02in the glass to less than or equal to 45 mole%. In some cases, the glass can be free or substantially free of Ti02.

[0089] According to some embodiments, the amount of Ti02present in the glass can be: 0.0 mol% to 45.0 mol%, 0.0 mol% to 40.0 mol%, 0.0 mol% to 35.0 mol%, 0.0 mol% to 30.0 mol%, 0.0 mol% to 25.0 mol%, 0.0 mol% to 22.0 mol%, 0.0 mol% to 20.0 mol%, 0.0 mol% to 18.0 mol%, 0.0 mol% to 13.0 mol%, 0.0 mol% to 12.0 mol%, 0.0 mol% to 6.0 mol%, 0.03 mol% to 45.0 mol%, 0.03 mol% to 40.0 mol%, 0.03 mol% to 35.0 mol%, 0.03 mol% to 30.0 mol%, 0.03 mol% to 25.0 mol%, 0.03 mol% to 22.0 mol%, 0.03 mol% to 20.0 mol%, 0.03 mol% to 18.0 mol%, 0.03 mol% to 13.0 mol%, 0.03 mol% to 12.0 mol%, 0.03 mol% to 6.0 mol%, 6.0 mol% to 45.0 mol%, 6.0 mol% to 40.0 mol%, 6.0 mol% to 35.0 mol%, 6.0 mol% to 30.0 mol%, 6.0 mol% to 25.0 mol%, 6.0 mol% to 22.0 mol%, 6.0 mol% to 20.0 mol%, 6.0 mol% to 18.0 mol%, 6.0 mol% to 13.0 mol%, 6.0 mol% to 12.0 mol%, 12.0 mol% to 45.0 mol%, 12.0 mol% to 40.0 mol%, 12.0 mol% to 35.0 mol%, 12.0 mol% to 30.0 mol%, 12.0 mol% to 25.0 mol%, 12.0 mol% to 22.0 mol%, 12.0 mol% to 20.0 mol%, 12.0 mol% to 18.0 mol%, 13.0 mol% to 45.0 mol%, 13.0 mol% to 40.0 mol%, 13.0 mol% to 35.0 mol%, 13.0 mol% to 30.0 mol%, 13.0 mol% to 25.0 mol%, 13.0 mol% to 22.0 mol%, 13.0 mol% to 20.0 mol%, 13.0 mol% to 18.0 mol%, 18.0 mol% to 45.0 mol%, 18.0 mol% to 40.0 mol%, 18.0 mol% to 35.0 mol%, 18.0 mol% to 30.0 mol%, 18.0 mol% to 25.0 mol%, 18.0 mol% to 22.0 mol%, 18.0 mol% to 20.0 mol%, 20.0 mol% to 45.0 mol%, 20.0 mol% to 40.0 mol%, 20.0 mol% to 35.0 mol%, 20.0 mol% to 30.0 mol%, 22.0 mol% to 45.0 mol%, 22.0 mol% to 40.0 mol%, 22.0 mol% to 35.0 mol%, 22.0 mol% to 30.0 mol%, 25.0 mol% to 45.0 mol%, 25.0 mol% to 40.0 mol%, 25.0 mol% to 35.0 mol%, 25.0 mol% to 30.0 mol%, 30.0 mol% to 45.0 mol%, 30.0 mol% to 40.0 mol%, 30.0 mol% to 35.0 mol%, 35.0 mol% to 45.0 mol%, 35.0 mol% to 40.0 mol%, 40.0 mol% to 45.0 mol%, or 45.0 mol% to 100.0 mol%.0 mol% to 30.0 mol%, 30.0 mol% to 45.0 mol%, or 30.0 mol% to 40.0 mol%. In some examples, the amount of Ti02present is less than or equal to 18 mol%. In some examples, the amount of Ti02present is 0.0 wt% to 7.05 wt%. For example, the amount of Ti02present can be: 0.0 wt% to 7.05 wt%, 2.0 wt% to 7.05 wt%, 5.0 wt% to 7.05 wt%, or 2.0 wt% to 5.0 wt%. In some embodiments, it is found that concentrations of Ti02greater than 18.0 mol% (and in some cases greater than 22.0 mol%) result in glasses with lower transmission than desired and / or cause the melt to tend to crystallize and / or become phase separated. Thus, in some embodiments, the amount of Ti02present in the glass is preferably 22.0 mol% or less or more preferably 18.0 mol% or less.

[0090] Similar to titanium oxide, niobium oxide (Nb2O5) can be used in some aspects of the disclosure to increase the refractive index of the glass while maintaining a low density. However, niobium oxide can introduce a yellow color to the glass that cannot be bleached out in the same manner as titanium oxide, which can result in a loss of transmission (particularly in the blue and UV ranges). Similar to titanium oxide, niobium oxide can cause crystallization and / or phase separation of the melt. In some cases, niobium oxide can provide a glass with a high optical dispersion, which can be significantly higher than that induced when titanium oxide and some other refractive index enhancers are added at similar concentrations. The effects of niobium oxide can be influenced by other components of the glass, and thus it can be challenging to determine the exact limits of niobium oxide. Thus, according to one aspect of the disclosure, the amount of niobium oxide is limited to less than or equal to 20 mol%, and in some cases, the glass can be free or substantially free of niobium oxide. However, in some examples, based on the component content of the glass and / or in cases where, for example, high blue light transmission is not a high priority, the amount of niobium oxide present can be greater than 20 mol%. In some embodiments, amounts of Nb2O5less than 0.5 mol% were found to increase the difficulty of achieving a high refractive index glass with an acceptable glass density. In some embodiments, it was found that for lower concentrations of Nb2O5, it was difficult to achieve a glass with a high refractive index at a low density. However, when the concentration of Nb2O5was too high (e.g., greater than 30.0 mol% and in some cases greater than 25.0 mol%), the resulting glass can have a transmission that is lower than desired and / or the glass melt can tend to crystallize and / or become phase separated. Thus, according to some embodiments, the Nb2O5present in the glass can be from 0.0 mol% to 30.0 mol%.For example, the Nb2O5present in the glass can be: 0.0 mol% to 30.0 mol%, 0.0 mol% to 25.0 mol%, 0.0 mol% to 20.0 mol%, 0.0 mol% to 16.0 mol%, 0.0 mol% to 12.0 mol%, 0.0 mol% to 10.0 mol%, 0.0 mol% to 6.0 mol%, 0.0 mol% to 1.0 mol%, 0.0 mol% to 0.6 mol%, 0.0 mol% to 0.5 mol%, 0.5 mol% to 30.0 mol%, 0.5 mol% to 25.0 mol%, 0.5 mol% to 20.0 mol%, 0.5 mol% to 16.0 mol%, 0.5 mol% to 12.0 mol%, 0.5 mol% to 10.0 mol%, 0.5 mol% to 6.0 mol%, 0.5 mol% to 1.0 mol%, 0.5 mol% to 0.6 mol%, 0.6 mol% to 30.0 mol%, 0.6 mol% to 25.0 mol%, 0.6 mol% to 20.0 mol%, 0.6 mol% to 16.0 mol%, 0.6 mol% to 12.0 mol%, 0.6 mol% to 10.0 mol%, 0.6 mol% to 6.0 mol%, 0.6 mol% to 1.0 mol%, 1.0 mol% to 30.0 mol%, 1.0 mol% to 25.0 mol%, 1.0 mol% to 20.0 mol%, 1.0 mol% to 16.0 mol%, 1.0 mol% to 12.0 mol%, 1.0 mol% to 10.0 mol%, 1.0 mol% to 6.0 mol%, 6.0 mol% to 30.0 mol%, 6.0 mol% to 25.0 mol%, 6.0 mol% to 20.0 mol%, 6.0 mol% to 16.0 mol%, 6.0 mol% to 12.0 mol%, 6.0 mol% to 10.0 mol%, 10.0 mol% to 30.0 mol%, 10.0 mol% to 25.0 mol%, 10.0 mol% to 20.0 mol%, 10.0 mol% to 16.0 mol%, 10.0 mol% to 12.0 mol%, 12.0 mol% to 30.0 mol%, 12.0 mol% to 25.0 mol%, 12.0 mol% to 20.0 mol%, 12.0 mol% to 16.0 mol%, 16.0 mol% to 30.0 mol%, 16.0 mol% to 25.0 mol%, 16.0 mol% to 20.0 mol%, 20.0 mol% to 30.0 mol%, 20.0 mol% to 25.0 mol%, or 25.0 mol% to 30.0 mol%. In some examples, the amount of Nb2O5present can be 0.3 wt% to 50.0 wt%.For example, the amount of Nb2O5present can be: 0.3 wt.% to 50.0 wt.%, 0.3 wt.% to 40.0 wt.%, 0.3 wt.% to 30.0 wt.%, 0.3 wt.% to 20.0 wt.%, 0.3 wt.% to 10.0 wt.%, 5.0 wt.% to 50.0 wt.%, 5.0 wt.% to 40.0 wt.%, 5.0 wt.% to 30.0 wt.%, 5.0 wt.% to 20.0 wt.%, 5.0 wt.% to 10.0 wt.%, 10.0 wt.% to 50.0 wt.%, 10.0 wt.% to 40.0 wt.%, 10.0 wt.% to 30.0 wt.%, 10.0 wt.% to 20.0 wt.%, 20.0 wt.% to 50.0 wt.%, 20.0 wt.% to 40.0 wt.%, 20.0 wt.% to 30.0 wt.%, 30.0 wt.% to 50.0 wt.%, or 30.0 wt.% to 40.0 wt.%. In some examples, the amount of Nb2O5present can be greater than 10.2 wt.% up to and including 20.0 wt.%. In some examples, the amount of Nb2O5present can be greater than 10.2 wt.% up to and including 50.0 wt.%.

[0091] In some embodiments, the glasses of the disclosure comprise Nb2O5and / or TiO2in amounts such that the sum of (Nb2O5+ TiO2) is 8.0 wt.% to 50.0 wt.%. For example, the Nb2O5and / or TiO2present in the glass can be such that the sum of (Nb2O5+ TiO2) is: 8.0 wt.% to 50.0 wt.%, 10.0 wt.% to 50.0 wt.%, 15.0 wt.% to 50.0 wt.%, 18.0 wt.% to 50.0 wt.%, 22.0 wt.% to 50.0 wt.%, 30.0 wt.% to 50.0 wt.%, 40.0 wt.% to 50.0 wt.%, 8.0 wt.% to 40.0 wt.%, 10.0 wt.% to 40.0 wt.%, 15.0 wt.% to 40.0 wt.%, 18.0 wt.% to 40.0 wt.%, 22.0 wt.% to 40.0 wt.%, 30.0 wt.% to 40.0 wt.%, 8.0 wt.% to 30.0 wt.%, 10.0 wt.% to 30.0 wt.%, 15.0 wt.% to 30.0 wt.%, 18.0 wt.% to 30.0 wt.%, 22.0 wt.% to 30.0 wt.%, 8.0 wt.% to 22.0 wt.%, 10.0 wt.% to 22.0 wt.%, or 15.0 wt.% to 22.0 wt.%. In some examples, the sum of (Nb2O5+ TiO2) is greater than 22.0 wt.% up to and including 50.0 wt.%. In some examples, the Nb2O5and TiO2present in the glass can be such that the ratio of Nb2O5to TiO2(Nb2O5 / TiO2) is greater than or equal to 1.9 (in wt.%).

[0092] Zirconia (Zr02) is another example of an oxide that can increase the refractive index of the glasses of the disclosure while maintaining an acceptably low density. In some examples, Zr02may provide a glass with a higher density than the case of Ti02and Nb205, at similar refractive index values. Zr02also increases the viscosity of the melt, which can help protect the melt from crystallization. Unlike other refractive index enhancers that can provide a low density to the glass (e.g., Ti02and Nb205), Zr02does not introduce color in the visible and near-UV range to the glass, which can help maintain high transmission of the glass. However, high concentrations of zirconia can lead to crystallization of refractory minerals (e.g., zirconia (Zr02), zircon (ZrSi04), and calcium zirconate (CaZr03), among others), which can increase the liquidus temperature. As a result, crystallization can occur at lower viscosities, which can decrease the glass forming ability of the melt (i.e., can increase the critical cooling rate). To address these challenges, according to one aspect of the disclosure, the zirconia content in the glass is less than or equal to 20.0 mol%, and in some examples, the glass is free or substantially free of zirconia. In some cases, such as when there are low requirements for glass forming ability, the glass can include higher amounts of zirconia. For example, the Zr02present in the glass can be: 0.0 mol% to 30.0 mol%, 0.0 mol% to 25.0 mol%, 0.0 mol% to 20.0 mol%, 0.0 mol% to 15.0 mol%, 0.0 mol% to 10.0 mol%, 0.0 mol% to 5.0 mol%, 0.0 mol% to 1.0 mol%, 1.0 mol% to 30.0 mol%, 1.0 mol% to 25.0 mol%, 1.0 mol% to 20.0 mol%, 1.0 mol% to 15.0 mol%, 1.0 mol% to 10.0 mol%, 1.0 mol% to 5.0 mol%, 5.0 mol% to 30.0 mol%, 5.0 mol% to 25.0 mol%, 5.0 mol% to 20.0 mol%, 5.0 mol% to 15.0 mol%, 5.0 mol% to 10.0 mol%, 10.0 mol% to 30.0 mol%, 10.0 mol% to 25.0 mol%, 10.0 mol% to 20.0 mol%, 10.0 mol% to 15.0 mol%, 15.0 mol% to 30.0 mol%, 15.0 mol% to 25.0 mol%, or 15.0 mol% to 20.0 mol%. In some examples, the amount of Zr02present in the glass is 0.0 wt% to 15.0 wt%.For example, the Zr02that is present can be in an amount of: 0.0 wt% to 15.0 wt%, 2.0 wt% to 15.0 wt%, 2.5 wt% to 15.0 wt%, 5.0 wt% to 15.0 wt%, 8.0 wt% to 15.0 wt%, 10.0 wt% to 15.0 wt%, 0.0 wt% to 10.0 wt%, 2.0 wt% to 10.0 wt%, 2.5 wt% to 10.0 wt%, 5.0 wt% to 10.0 wt%, 8.0 wt% to 10.0 wt%, 0.0 wt% to 8.0 wt%, 2.0 wt% to 8.0 wt%, 2.5 wt% to 8.0 wt%, or 5.0 wt% to 8.0 wt%.

[0093] In some embodiments, rare earth metal oxides can be added to the glass composition to increase the refractive index of the glasses of the present disclosure. Examples of rare earth metal oxides that can be added to the glasses of the present disclosure include La2O3, Gd2O3, Yb2O3, Y2O3, and Sc2O3. The latter two elements' oxides (Y2O3 and Sc2O3) can also provide a glass with a relatively low density, lower than titania and niobia oxides at similar refractive indices. However, scandia (Sc2O3) can be expensive and thus can not be desirable for mass production. In some cases, Sc2O3 can be acceptable when the cost of the glass batch materials has a lower priority. Yttria (Y2O3) is less expensive than scandia. However, in some cases, Y2O3 can decrease the glass formability of the glass (i.e., increase the critical cooling rate), even at lower concentrations. Thus, according to some embodiments of the present disclosure, the glass can be free or substantially free of Y2O3. In some embodiments, the glass can include a small amount of Y2O3, for example, from 0.0 to 1.5 mole percent. For example, the glass can include Y2O3 in an amount from 0.0 mole percent to 1.5 mole percent, from 0.0 mole percent to 1.25 mole percent, from 0.0 mole percent to 1.0 mole percent, from 0.0 mole percent to 0.75 mole percent, from 0.0 mole percent to 0.5 mole percent, from 0.0 mole percent to 0.25 mole percent, from 0.25 mole percent to 1.5 mole percent, from 0.25 mole percent to 1.25 mole percent, from 0.25 mole percent to 1.0 mole percent, from 0.25 mole percent to 0.75 mole percent, from 0.25 mole percent to 0.5 mole percent, from 0.5 mole percent to 1.5 mole percent, from 0.5 mole percent to 1.25 mole percent, from 0.5 mole percent to 1.0 mole percent, from 0.5 mole percent to 0.75 mole percent, from 0.75 mole percent to 1.5 mole percent, from 0.75 mole percent to 1.25 mole percent, from 0.75 mole percent to 1.0 mole percent, or from 1.0 mole percent to 1.5 mole percent. In some embodiments, it was found that while Y2O3 can facilitate the formation of a glass with a high refractive index-to-density ratio, higher amounts of Y2O3 can result in crystallization of the glass melt during cooling. However, in some embodiments, acceptable glass formability was achieved with Y2O3 concentrations higher than 1.5 mole percent. Thus, according to other embodiments of the present disclosure, the glass can include Y2O3 in an amount greater than 1.5 mole percent, for example, in an amount up to 3.0 mole percent, or up to 4.0 mole percent, or up to 5.0 mole percent, or in an amount from 1.5 mole percent to 5.0 mole percent, from 1.5 mole percent to 4.0 mole percent, from 1.5 mole percent to 3.0 mole percent, from 2.0 mole percent to 5.0 mole percent, from 2.0 mole percent to 4.0 mole percent, or from 3.0 mole percent to 5.0 mole percent. In some embodiments, the glass can include Y2O3 in an amount from 0.0 weight percent to 10.0 weight percent.For example, the glass can include Y2O3 in an amount of 0.0 wt.% to 10.0 wt.%, 2.0 wt.% to 10.0 wt.%, or 5.0 wt.% to 10.0 wt.%.

[0094] In some aspects, lanthanum oxide (La2O3) can be a preferred refractive index enhancer in addition to Y2O3 and Sc2O3 in the rare earth metal oxides. La2O3 can provide lower density for the glasses of the present disclosure at similar refractive indices compared to several other rare earth metal oxides. La2O3 can also provide acceptable good glass forming for the glass compositions and is one of the most cost effective rare earth metal oxides. Thus, in some aspects of the present disclosure, the glass compositions can include at least some amount of La2O3. However, in some cases, when the concentration of La2O3 becomes too high, lanthanum oxide can cause precipitation of refractory species, such as lanthanum silicates (La4Si3O 12 , La2SiO5, La2Si2O7), lanthanum borates (LaBO3, LaB3O6), lanthanum niobates (LaNbO4), lanthanum zirconates (La2ZrO5, La2Zr2O7), and lanthanum titanates (La2TiO5, La2Ti2O7), etc., which can increase the liquidus temperature of the glass and can reduce the glass forming ability of the composition. In addition, high concentrations of La2O3 can stimulate phase separation in the melt, which results in loss of transmittance of the resulting glass. Similar negative effects can also occur after adding other rare earth metal oxides in high concentrations. Optionally, other rare earth metal oxides, such as Gd2O3 and Yb2O3, can be added to the glass compositions. The rare earth metal oxides, such as Gd2O3 and Yb2O3, can facilitate maintaining high refractive index and good transmittance of the glass, but can undesirably increase the density of the glass. To address these challenges, some embodiments of the present disclosure include limiting the content of RE m O n of the glass compositions. According to embodiments of the present disclosure, the total content of rare earth metal oxides RE m O n may be present in an amount less than or equal to 45 mol.%. In some embodiments, the glass compositions can be free or substantially free of rare earth metal oxides. For example, the total content of rare earth metal oxides RE m O nmay be: 0.0 mol% to 45.0 mol%, 0.0 mol% to 40.0 mol%, 0.0 mol% to 30.0 mol%, 0.0 mol% to 23.0 mol%, 0.0 mol% to 20.0 mol%, 0.0 mol% to 15.0 mol%, 0.0 mol% to 10.0 mol%, 0.0 mol% to 5.0 mol%, 0.0 mol% to 1.0 mol%, 1.0 mol% to 45.0 mol%, 1.0 mol% to 40.0 mol%, 1.0 mol% to 30.0 mol%, 1.0 mol% to 23.0 mol%, 1.0 mol% to 20.0 mol%, 1.0 mol% to 15.0 mol%, 1.0 mol% to 10.0 mol%, 1.0 mol% to 5.0 mol%, 5.0 mol% to 45.0 mol%, 5.0 mol% to 40.0 mol%, 5.0 mol% to 30.0 mol%, 5.0 mol% to 23.0 mol%, 5.0 mol% to 20.0 mol%, 5.0 mol% to 15.0 mol%, 5.0 mol% to 10.0 mol%, 10.0 mol% to 45.0 mol%, 10.0 mol% to 40.0 mol%, 10.0 mol% to 30.0 mol%, 10.0 mol% to 23.0 mol%, 10.0 mol% to 20.0 mol%, 10.0 mol% to 15.0 mol%, 15.0 mol% to 45.0 mol%, 15.0 mol% to 40.0 mol%, 15.0 mol% to 30.0 mol%, 15.0 mol% to 23.0 mol%, 15.0 mol% to 20.0 mol%, or 20.0 mol% to 45.0 mol%. In some embodiments, it is found that RE m O n Total content can cause the glass melt to be prone to crystallization during cooling and / or can cause the density of the glass to increase to a higher level than desired.

[0095] In some embodiments, the glasses of the present disclosure can optionally include additional and / or alternative refractive index enhancers (e.g., tungsten oxide (WO3), tantalum oxide (Ta2O5), thorium oxide (ThO2), bismuth oxide (Bi2O3)), which, if present, can be used in small amounts. In some embodiments, the glasses of the present disclosure are free or substantially free of tungsten oxide (WO3), tantalum oxide (Ta2O5), thorium oxide (ThO2), bismuth oxide (Bi2O3). In some embodiments, the glasses can optionally include additional and / or alternative refractive index enhancers selected from the group consisting of vanadium pentoxide (V2O5), molybdenum oxide (MoO3), germanium oxide (GeO2), tellurium oxide (TeO2), fluorides (e.g., ZrF4, LaF3, etc.), and thallium oxide (Tl2O). In some cases, refractive index enhancers such as V2O5, MoO3, GeO2, TeO2, fluorides, and Tl2O can not be as preferred due to low transmission, cost, and / or environmental considerations; however, in some cases, these refractive index enhancers can be used.

[0096] Ta2O5may increase the density of the glass and, in some examples, can cause the glass melt to crystallize upon cooling. In addition, Ta2O5may be costly in some cases. Thus, in some embodiments, it can be preferred to limit the amount of Ta2O5in the glass to an amount of 0.0 mol% to 1.5 mol%. For example, the Ta2O5may be present in an amount of 0.0 mol% to 1.5 mol%, 0.0 mol% to 1.0 mol%, 0.0 mol% to 0.5 mol%, 0.0 mol% to 0.25 mol%, or 0.0 mol% to 0.1 mol%. In some examples, the glass is free or substantially free of Ta2O5. In some embodiments, the glass can include 0.0 wt% to 1.0 wt% Ta2O5.

[0097] In some embodiments, the Bi2O3may be present in the glass in an amount of 0.0 mol% to 20.0 mol%. For example, the Bi2O3may be present in the glass in an amount of 0.0 mol% to 20.0 mol%, 0.0 mol% to 15.0 mol%, 0.0 mol% to 10.0 mol%, 0.0 mol% to 5.0 mol%, 0.0 mol% to 1.0 mol%, 1.0 mol% to 20.0 mol%, 1.0 mol% to 15.0 mol%, 1.0 mol% to 10.0 mol%, 1.0 mol% to 5.0 mol%, 5.0 mol% to 20.0 mol%, 5.0 mol% to 15.0 mol%, 5.0 mol% to 10.0 mol%, or 10.0 mol% to 20.0 mol%. In some embodiments, the glass is free or substantially free of Bi2O3. Higher amounts of Bi2O3may increase the density of the glass above 4.5 g / cm3 3and / or can become cost prohibitive and thus preferably the amount of Bi2O3in the glass is less than or equal to 20.0 mol.%.

[0098] In some embodiments, the amount of HfO2present in the glass can be from 0.0 mol.% to 5.0 mol.%. For example, the HfO2present can be in an amount from 0.0 mol.% to 5.0 mol.%, 0.0 mol.% to 4.0 mol.%, 0.0 mol.% to 3.0 mol.%, 0.0 mol.% to 2.0 mol.%, 0.0 mol.% to 1.0 mol.%, 1.0 mol.% to 5.0 mol.%, 1.0 mol.% to 4.0 mol.%, 1.0 mol.% to 3.0 mol.%, or 1.0 mol.% to 2.0 mol.%. HfO2can be cost prohibitive and can cause crystallization of the glass melt at high temperatures. Thus, preferably, the glass has less than 5.0 mol.% and in some instances less than 1.0 mol.% HfO2. In some embodiments, the glass can be free or substantially free of HfO2.

[0099] In some embodiments, the amount of TeO2present in the glass can be from 0.0 mol.% to 5.0 mol.%. For example, the TeO2present can be in an amount from 0.0 mol.% to 5.0 mol.%, 0.0 mol.% to 4.0 mol.%, 0.0 mol.% to 3.0 mol.%, 0.0 mol.% to 2.0 mol.%, 0.0 mol.% to 1.0 mol.%, 1.0 mol.% to 5.0 mol.%, 1.0 mol.% to 4.0 mol.%, 1.0 mol.% to 3.0 mol.%, or 1.0 mol.% to 2.0 mol.%. TeO2can be cost prohibitive and can cause an undesirable increase in the density of the glass. Thus, preferably, the glass has less than 5.0 mol.% and in some instances less than 1.0 mol.% TeO2. In some embodiments, the glass can be free or substantially free of TeO2.

[0100] In some embodiments, the amount of GeO2present in the glass can be from 0.0 wt.% to 2.0 wt.%. For example, the TeO2present can be in an amount from 0.0 wt.% to 2.0 wt.%, 0.1 wt.% to 2.0 wt.%, 0.1 wt.% to 1.5 wt.%, 0.5 wt.% to 2.0 wt.%, 0.5 wt.% to 1.5 wt.%, or 1.0 wt.% to 2.0 wt.%.

[0101] According to embodiments of the disclosure, the glass can include one or more modifiers. As described above, the term "modifier" refers to an oxide of a monovalent or divalent metal, i.e., M2O or MO, where "M" represents the metal. Modifiers can be added to the glass compositions of the disclosure to promote improved glass forming ability of the melt, i.e., to lower the critical cooling rate. Examples of modifiers that can be used in the glasses of the disclosure include alkali and alkaline earth modifiers (e.g., CaO, MgO, BaO, Li2O, Na2O, and K2O), as well as other modifiers (e.g., ZnO and Ag2O). According to one embodiment, the glass composition can include CaO and / or Li2O, which are found to provide the desired ratio of the glass's refractive index to density. In some embodiments, other alkali and alkaline earth metal oxides (e.g., Na2O, K2O, MgO, SrO, BaO, etc.) and other modifiers that do not provide any color (e.g., ZnO, Ag2O, etc.) can be included in the glass composition. While these other modifiers can not contribute as much as CaO and Li2O to providing the desired refractive index and / or density, these modifiers can be added to the glass composition to provide other properties. For example, barium oxide (BaO), potassium oxide (K2O), sodium oxide (Na2O), etc. can be added to increase the solubility of refractive index enhancers (e.g., TiO2, Nb2O5, ZrO2, etc.) in the glass melt, which can result in an overall increase in the glass's refractive index and / or an increase in the ratio of the refractive index to density. According to one embodiment of the disclosure, the glass can include at least CaO as a modifier, as CaO is found to provide a good balance between the desired properties of density, refractive index, and glass forming ability. Thus, in many examples of the disclosure, all or at least a portion of the modifiers present in the glass composition are in the form of CaO.

[0102] According to embodiments of the disclosure, one or more modifiers can be present in the glass composition individually in an amount of 0.0 mol% to 32.0 mol%. For example, one or more modifiers can be present in the glass composition individually in an amount of 0.0 mol% to 32.0 mol%, 0.0 mol% to 31.0 mol%, 0.0 mol% to 30.0 mol%, 0.0 mol% to 25.0 mol%, 0.0 mol% to 20.0 mol%, 0.0 mol% to 15.0 mol%, 0.0 mol% to 10.0 mol%, 0.0 mol% to 8.0 mol%, 0.0 mol% to 7.0 mol%, 0.0 mol% to 5.0 mol%, 0.0 mol% to 2.0 mol%, 2.0 mol% to 32.0 mol%, 2.0 mol% to 31.0 mol%, 2.0 mol% to 30.0 mol%, 2.0 mol% to 25.0 mol%, 2.0 mol% to 20.0 mol%, 2.0 mol% to 15.0 mol%, 2.0 mol% to 10.0 mol%, 2.0 mol% to 8.0 mol%, 2.0 mol% to 7.0 mol%, 2.0 mol% to 5.0 mol%, 5.0 mol% to 32.0 mol%, 5.0 mol% to 31.0 mol%, 5.0 mol% to 30.0 mol%, 5.0 mol% to 25.0 mol%, 5.0 mol% to 20.0 mol%, 5.0 mol% to 15.0 mol%, 5.0 mol% to 10.0 mol%, 5.0 mol% to 8.0 mol%, 5.0 mol% to 7.0 mol%, 7.0 mol% to 32.0 mol%, 7.0 mol% to 31.0 mol%, 7.0 mol% to 30.0 mol%, 7.0 mol% to 25.0 mol%, 7.0 mol% to 20.0 mol%, 7.0 mol% to 15.0 mol%, 7.0 mol% to 10.0 mol%, 8.0 mol% to 32.0 mol%, 8.0 mol% to 31.0 mol%, 8.0 mol% to 30.0 mol%, 8.0 mol% to 25.0 mol%, 8.0 mol% to 20.0 mol%, 8.0 mol% to 15.0 mol%, 8.0 mol% to 10.0 mol%, 10.0 mol% to 32.0 mol%, 10.0 mol% to 31.0 mol%, 0.0 mol% to 30.0 mol%, 10.0 mol% to 25.0 mol%, 10.0 mol% to 20.0 mol%, or 10.0 mol% to 15.0 mol%. In some embodiments, the glass can be free or substantially free of modifiers.

[0103] In some embodiments, the amount of CaO present can be 0.0 mole % to 32.0 mole %. For example, the CaO present in the glass composition can be in an amount of 0.0 mole % to 32.0 mole %, 0.0 mole % to 31.0 mole %, 0.0 mole % to 30.0 mole %, 0.0 mole % to 25.0 mole %, 0.0 mole % to 20.0 mole %, 0.0 mole % to 15.0 mole %, 0.0 mole % to 10.0 mole %, 0.0 mole % to 8.0 mole %, 0.0 mole % to 7.0 mole %, 0.0 mole % to 5.0 mole %, 0.0 mole % to 2.0 mole %, 2.0 mole % to 32.0 mole %, 2.0 mole % to 31.0 mole %, 2.0 mole % to 30.0 mole %, 2.0 mole % to 25.0 mole %, 2.0 mole % to 20.0 mole %, 2.0 mole % to 15.0 mole %, 2.0 mole % to 10.0 mole %, 2.0 mole % to 8.0 mole %, 2.0 mole % to 7.0 mole %, 2.0 mole % to 5.0 mole %, 5.0 mole % to 32.0 mole %, 5.0 mole % to 31.0 mole %, 5.0 mole % to 30.0 mole %, 5.0 mole % to 25.0 mole %, 5.0 mole % to 20.0 mole %, 5.0 mole % to 15.0 mole %, 5.0 mole % to 10.0 mole %, 5.0 mole % to 8.0 mole %, 5.0 mole % to 7.0 mole %, 7.0 mole % to 32.0 mole %, 7.0 mole % to 31.0 mole %, 7.0 mole % to 30.0 mole %, 7.0 mole % to 25.0 mole %, 7.0 mole % to 20.0 mole %, 7.0 mole % to 15.0 mole %, 7.0 mole % to 10.0 mole %, 8.0 mole % to 32.0 mole %, 8.0 mole % to 31.0 mole %, 8.0 mole % to 30.0 mole %, 8.0 mole % to 25.0 mole %, 8.0 mole % to 20.0 mole %, 8.0 mole % to 15.0 mole %, 8.0 mole % to 10.0 mole %, 10.0 mole % to 32.0 mole %, 10.0 mole % to 31.0 mole %, 10.0 mole % to 30.0 mole %, 10.0 mole % to 25.0 mole %, 10.0 mole % to 20.0 mole %, or 10.0 mole % to 15.0 mole %.In some examples, CaO present in the glass can be in an amount from 0.5 wt.% to 25.0 wt.%, 1.0 wt.% to 25.0 wt.%, 5.0 wt.% to 25.0 wt.%, 8.0 wt.% to 25.0 wt.%, 10.0 wt.% to 25.0 wt.%, 0.5 wt.% to 20.0 wt.%, 1.0 wt.% to 20.0 wt.%, 5.0 wt.% to 20.0 wt.%, 8.0 wt.% to 20.0 wt.%, 10.0 wt.% to 20.0 wt.%, 0.5 wt.% to 15.0 wt.%, 1.0 wt.% to 15.0 wt.%, 5.0 wt.% to 15.0 wt.%, 8.0 wt.% to 15.0 wt.%, 10.0 wt.% to 15.0 wt.%, 0.5 wt.% to 10.0 wt.%, 1.0 wt.% to 10.0 wt.%, 5.0 wt.% to 10.0 wt.%, or 8.0 wt.% to 10.0 wt.%. In some examples, the amount of CaO present can be greater than 8.0 wt.% up to and including 25.0 wt.%. In some embodiments, concentrations of CaO greater than 32.0 mol% can be found to increase the difficulty of producing a glass having a higher refractive index and / or can cause the glass melt to be prone to crystallization.

[0104] In some embodiments, the amount of ZnO present in the glass can be from 0.0 mol% to 10.0 mol%. For example, the amount of ZnO present can be: from 0.0 mol% to 10.0 mol%, from 0.0 mol% to 8.0 mol%, from 0.0 mol% to 6.0 mol%, from 0.0 mol% to 4.0 mol%, from 0.0 mol% to 2.0 mol%, from 0.0 mol% to 1.0 mol%, from 1.0 mol% to 10.0 mol%, from 1.0 mol% to 8.0 mol%, from 1.0 mol% to 6.0 mol%, from 1.0 mol% to 4.0 mol%, from 1.0 mol% to 2.0 mol%, from 2.0 mol% to 10.0 mol%, from 2.0 mol% to 8.0 mol%, from 2.0 mol% to 6.0 mol%, from 2.0 mol% to 4.0 mol%, from 4.0 mol% to 10.0 mol%, from 4.0 mol% to 8.0 mol%, or from 4.0 mol% to 6.0 mol%. In some examples, the amount of ZnO present is less than or equal to 2.0 mol%, including 0.0 mol%. It has been found that in some embodiments, at higher concentrations of ZnO, the glass forming ability of the melt decreases and the melt can be prone to crystallization during cooling. Thus, in some examples, the concentration of ZnO is less than or equal to 10.0 mol%, less than or equal to 8.0 mol%, less than or equal to 6.0 mol%, less than or equal to 4.0 mol%, and in some cases less than or equal to 2.0 mol%. In some embodiments of the disclosure, it has been found that the addition of ZnO in amounts greater than 2.0 mol% results in crystallization of the glass melt during cooling, and thus in some embodiments, it is preferred that ZnO be present in amounts less than or equal to 2.0 mol%. In some examples, the amount of ZnO present is from 0.0 wt% to 2.0 wt%.

[0105] In some embodiments, the amount of Li20 present in the glass can be from 0.0 mol% to 7.0 mol%. For example, the Li20 present can be in an amount from 0.0 mol% to 7.0 mol%, from 0.0 mol% to 5.0 mol%, from 0.0 mol% to 3.0 mol%, from 0.0 mol% to 1.0 mol%, from 1.0 mol% to 7.0 mol%, from 1.0 mol% to 5.0 mol%, from 1.0 mol% to 3.0 mol%, from 3.0 mol% to 7.0 mol%, from 3.0 mol% to 5.0 mol%, or from 5.0 mol% to 7.0 mol%. In some examples, the amount of Li20 present is from 0.0 wt% to 2.0 wt%. In some glasses, Li20 can have a negative impact on the glass forming ability of the glass composition, and thus in some embodiments, the glass can be free or substantially free of Li20.

[0106] In some embodiments, the amount of BaO present in the glass can be from 0.0 mol% to 15.0 mol%. For example, the amount of BaO present can be from 0.0 mol% to 15.0 mol%, 0.0 mol% to 12.0 mol%, 0.0 mol% to 10.0 mol%, 0.0 mol% to 5.0 mol%, 0.0 mol% to 3.0 mol%, 0.0 mol% to 1.0 mol%, 1.0 mol% to 15.0 mol%, 1.0 mol% to 12.0 mol%, 1.0 mol% to 10.0 mol%, 1.0 mol% to 5.0 mol%, 3.0 mol% to 15.0 mol%, 3.0 mol% to 12.0 mol%, 3.0 mol% to 10.0 mol%, 3.0 mol% to 5.0 mol%, 5.0 mol% to 15.0 mol%, or 5.0 mol% to 12.0 mol%. In some examples, the amount of BaO present is from 0.0 wt% to 10.0 wt%, 0.0 wt% to 8.0 wt%, 0.0 wt% to 5.0 wt%, 0.0 wt% to 1.0 wt%, 1.0 wt% to 10.0 wt%, 1.0 wt% to 8.0 wt%, or 1.0 wt% to 5.0 wt%. In some embodiments, amounts of BaO greater than 15.0 mol% can be found to increase the density of the glass above a desired limit.

[0107] In some embodiments, the amount of MgO present in the glass can be from 0.0 mol% to 5.0 mol%. For example, the MgO present can be in an amount from 0.0 mol% to 5.0 mol%, 0.0 mol% to 3.0 mol%, 0.0 mol% to 1.0 mol%, 1.0 mol% to 5.0 mol%, 1.0 mol% to 3.0 mol%, or 3.0 mol% to 5.0 mol%. In some glasses, MgO can negatively impact the glass forming ability of the glass composition, and thus in some embodiments, the glass can be free or substantially free of MgO.

[0108] According to one embodiment of the disclosure, the amount of one or more modifiers present in the glass can be such that the ratio of CaO to the sum of (Li20 + Na20 + K20 + MgO + CaO + SrO + BaO + ZnO) in weight percent (expressed as CaO / (Li20 + Na20 + K20 + MgO + CaO + SrO + BaO + ZnO)) is greater than or equal to 0.50.

[0109] In some embodiments, the one or more modifying agents can be present in an amount such that the sum of the total content of divalent metal oxides (RO) plus the total content of alkali metal oxides (Alk2O) (denoted as (RO + Alk2O)) is 0.0 mole % to 40.0 mole %. For example, the one or more modifying agents can be present in an amount such that (RO + Alk2O) is: 0.0 mole % to 40.0 mole %, 0.0 mole % to 36.0 mole %, 0.0 mole % to 30.0 mole %, 0.0 mole % to 22.0 mole %, 0.0 mole % to 20.0 mole %, 0.0 mole % to 15.0 mole %, 0.0 mole % to 10.0 mole %, 0.0 mole % to 5.0 mole %, 0.0 mole % to 1.0 mole %, 1.0 mole % to 40.0 mole %, 1.0 mole % to 36.0 mole %, 1.0 mole % to 30.0 mole %, 1.0 mole % to 22.0 mole %, 1.0 mole % to 20.0 mole %, 1.0 mole % to 15.0 mole %, 1.0 mole % to 10.0 mole %, 1.0 mole % to 5.0 mole %, 5.0 mole % to 40.0 mole %, 5.0 mole % to 36.0 mole %, 5.0 mole % to 30.0 mole %, 5.0 mole % to 22.0 mole %, 5.0 mole % to 20.0 mole %, 5.0 mole % to 15.0 mole %, 5.0 mole % to 10.0 mole %, 10.0 mole % to 40.0 mole %, 10.0 mole % to 36.0 mole %, 10.0 mole % to 30.0 mole %, 10.0 mole % to 22.0 mole %, 10.0 mole % to 20.0 mole %, 20.0 mole % to 40.0 mole %, 20.0 mole % to 36.0 mole %, 20.0 mole % to 30.0 mole %, 20.0 mole % to 22.0 mole %, 22.0 mole % to 40.0 mole %, 22.0 mole % to 36.0 mole %, 22.0 mole % to 30.0 mole %, or 30.0 mole % to 40.0 mole %.

[0110] In some embodiments, the one or more modifiers present can be in an amount such that the sum of the total content of divalent metal oxides (RO) plus the total content of monovalent metal oxides (R2O) (denoted as (RO+R2O)) is 0.0 mole% to 40.0 mole%. In the case of higher amounts of RO and / or R2O modifiers, the glass melt can tend to crystallize and can be challenging to achieve the desired high refractive index. Further, higher amounts of RO and R2O can reduce the chemical durability of the glass. Examples of monovalent metal oxides R2O include alkali metal oxides. Examples of divalent metal oxides include alkaline earth metal oxides, ZnO, and PbO. For example, the one or more modifiers present can be in an amount such that (RO+R2O) is: 0.0 mole% to 40.0 mole%, 0.0 mole% to 36.0 mole%, 0.0 mole% to 30.0 mole%, 0.0 mole% to 22.0 mole%, 0.0 mole% to 20.0 mole%, 0.0 mole% to 15.0 mole%, 0.0 mole% to 10.0 mole%, 0.0 mole% to 5.0 mole%, 0.0 mole% to 1.0 mole%, 1.0 mole% to 40.0 mole%, 1.0 mole% to 36.0 mole%, 1.0 mole% to 30.0 mole%, 1.0 mole% to 22.0 mole%, 1.0 mole% to 20.0 mole%, 1.0 mole% to 15.0 mole%, 1.0 mole% to 10.0 mole%, 1.0 mole% to 5.0 mole%, 5.0 mole% to 40.0 mole%, 5.0 mole% to 36.0 mole%, 5.0 mole% to 30.0 mole%, 5.0 mole% to 22.0 mole%, 5.0 mole% to 20.0 mole%, 5.0 mole% to 15.0 mole%, 5.0 mole% to 10.0 mole%, 10.0 mole% to 40.0 mole%, 10.0 mole% to 36.0 mole%, 10.0 mole% to 30.0 mole%, 10.0 mole% to 22.0 mole%, 10.0 mole% to 20.0 mole%, 20.0 mole% to 40.0 mole%, 20.0 mole% to 36.0 mole%, 20.0 mole% to 30.0 mole%, 20.0 mole% to 22.0 mole%, 22.0 mole% to 40.0 mole%, 22.0 mole% to 36.0 mole%, 22.0 mole% to 30.0 mole%, or 30.0 mole% to 40.0 mole%.

[0111] In some embodiments, the glass can include a total amount of divalent metal oxide (RO) present in an amount greater than or equal to 3.0 mole percent. For example, the glass can include a total amount of RO (where RO includes alkaline earth metal oxides, ZnO, PbO, etc.) in an amount greater than or equal to 3.0 mole percent, greater than or equal to 5.0 mole percent, greater than or equal to 10.0 mole percent, greater than or equal to 15.0 mole percent, greater than or equal to 20.0 mole percent, greater than or equal to 25.0 mole percent, or greater than or equal to 30.0 mole percent. In some embodiments, it is found that at lower amounts of RO, it can be difficult to accommodate refractive index enhancing species (examples of which include TiO2, Nb2O5, and ZrO2, etc.) in the glass composition, which leads to a glass melt that tends to crystallize during cooling.

[0112] In some embodiments, TiO2, Nb2O5, ZrO2, Bi2O3, and WO3may not be present in the glass or present in an amount such that the sum of (RE m O n + Ti O2+ Nb2O5+ ZrO2+ Bi2O3+ WO3) is greater than or equal to 25.0 mole percent, where RE m O n is the total amount of rare earth metal oxide present in the glass composition. In some examples, when these species are present such that the sum of (RE m O n + Ti O2+ Nb2O5+ ZrO2+ Bi2O3+ WO3) is less than 25.0 mole percent, it can be difficult to form a glass with the desired high refractive index.

[0113] In some embodiments, Si02, B203, Alk20, MgO, CaO, SrO, BaO, and ZnO can not be present in the glass or can be present in amounts such that the sum of (Si02+ B203+ Alk20+ MgO+ CaO+ SrO+ BaO+ ZnO) is less than or equal to 69.0 mole percent, where Alk20 is the total content of alkali oxides in the glass composition. In some examples, the sum of (Si02+ B203+ Alk20+ MgO+ CaO+ SrO+ BaO+ ZnO) can be in the range of 4.0 mole percent to 69.0 mole percent. In some examples, it can be difficult to form a glass having the desired high refractive index when these species are present in amounts such that the sum of (Si02+ B203+ Alk20+ MgO+ CaO+ SrO+ BaO+ ZnO) is greater than 69.0 mole percent. For example, in the case of BaO, higher concentrations can make it difficult to form a glass having the desired high refractive index at low density. In some embodiments, CaO, SrO, and / or BaO can or can not be present in the glass such that the sum of (CaO+ SrO+ BaO) is 0.2 percent or greater by weight.

[0114] In some embodiments, the glass can comprise CdO in an amount in the range of 0.0 mole percent to 15.0 mole percent. For example, the glass can comprise CdO in an amount in the range of 0.0 mole percent to 15.0 mole percent, 0.0 mole percent to 10.0 mole percent, 0.0 mole percent to 5.0 mole percent, 0.0 mole percent to 1.0 mole percent, 1.0 mole percent to 15.0 mole percent, 1.0 mole percent to 10.0 mole percent, 1.0 mole percent to 5.0 mole percent, 5.0 mole percent to 15.0 mole percent, or 5.0 mole percent to 10.0 mole percent. In some examples, the glass is free or substantially free of CdO.

[0115] In some embodiments, the glass can comprise PbO in an amount in the range of 0.0 mole percent to 1.0 mole percent. For example, the glass can comprise PbO in an amount in the range of 0.0 mole percent to 1.0 mole percent, 0.0 mole percent to 0.75 mole percent, 0.0 mole percent to 0.5 mole percent, or 0.0 mole percent to 0.1 mole percent. In some examples, the glass is free or substantially free of PbO. In other embodiments of the disclosure, the glass can comprise PbO in an amount greater than 1.0 mole percent, for example, in an amount up to 2.0 mole percent, or up to 3.0 mole percent, or up to 4.0 mole percent, or up to 5.0 mole percent, or in an amount in the range of 1.0 mole percent to 5.0 mole percent, 1.0 mole percent to 4.0 mole percent, 1.0 mole percent to 3.0 mole percent, 2.0 mole percent to 5.0 mole percent, 2.0 mole percent to 4.0 mole percent, or 3.0 mole percent to 5.0 mole percent.

[0116] In some embodiments of the disclosure, the glass comprises at least one of La2O3, Yb2O3, Gd2O3, TiO2, and Nb2O5. For example, SiO2, B2O3, La2O3, Yb2O3, Gd2O3, TiO2, and / or Nb2O5 present in the glass can be such that the ratio of (SiO2+B2O3) / (La2O3+Yb2O3+TiO2+Nb2O5) is 0.3 or more (in wt%). In another example, SiO2, B2O3, La2O3, Yb2O3, Gd2O3, TiO2, and / or Nb2O5 present in the glass can be such that the ratio of (TiO2+Nb2O5) / (La2O3+Gd2O3+Yb2O3) is less than 1.35 (in wt%).

[0117] In some embodiments, the glass comprises Gd2O3 in an amount of 0.0 wt% to 20.0 wt%. For example, the glass can comprise Gd2O3 in an amount of 0.0 wt% to 20.0 wt%, 0.0 wt% to 15.0 wt%, 0.0 wt% to 10.0 wt%, 0.0 wt% to 5.0 wt%, 2.0 wt% to 20.0 wt%, 2.0 wt% to 15.0 wt%, 2.0 wt% to 10.0 wt%, 2.0 wt% to 5.0 wt%, 5.0 wt% to 20.0 wt%, 5.0 wt% to 15.0 wt%, 5.0 wt% to 10.0 wt%, 10.0 wt% to 20.0 wt%, 10.0 wt% to 15.0 wt%, or 15.0 wt% to 20.0 wt%.

[0118] In some embodiments, the glass comprises La2O3and / or Gd2O3in an amount such that the sum of (La2O3+ Gd2O3) is 0.0 wt.% to 40.0 wt.% (in wt.%). For example, the sum of (La2O3+ Gd2O3) in the glass can be, in wt.%, 0.0 wt.% to 40.0 wt.%, 0.0 wt.% to 35.0 wt.%, 0.0 wt.% to 30.0 wt.%, 0.0 wt.% to 25.0 wt.%, 0.0 wt.% to 20.0 wt.%, 0.0 wt.% to 15.0 wt.%, 0.0 wt.% to 10.0 wt.%, 0.0 wt.% to 5.0 wt.%, 5.0 wt.% to 40.0 wt.%, 5.0 wt.% to 35.0 wt.%, 5.0 wt.% to 30.0 wt.%, 5.0 wt.% to 25.0 wt.%, 5.0 wt.% to 20.0 wt.%, 5.0 wt.% to 15.0 wt.%, 5.0 wt.% to 10.0 wt.%, 10.0 wt.% to 40.0 wt.%, 10.0 wt.% to 35.0 wt.%, 10.0 wt.% to 30.0 wt.%, 10.0 wt.% to 25.0 wt.%, 10.0 wt.% to 20.0 wt.%, 10.0 wt.% to 15.0 wt.%, 15.0 wt.% to 40.0 wt.%, 15.0 wt.% to 35.0 wt.%, 15.0 wt.% to 30.0 wt.%, 15.0 wt.% to 25.0 wt.%, 15.0 wt.% to 20.0 wt.%, 20.0 wt.% to 40.0 wt.%, 20.0 wt.% to 35.0 wt.%, 20.0 wt.% to 30.0 wt.%, 20.0 wt.% to 25.0 wt.%, 25.0 wt.% to 40.0 wt.%, 25.0 wt.% to 35.0 wt.%, 25.0 wt.% to 30.0 wt.%, or 30.0 wt.% to 40.0 wt.%.

[0119] According to some embodiments, the glass of the present disclosure comprises CaO, SrO, BaO, Nb2Os, and / or TiO2in an amount such that the ratio of (CaO + SrO + BaO) / (Nb2Os + TiO2) is greater than or equal to 0.45 (in wt.%). For example, the glass of the present disclosure comprises CaO, SrO, BaO, Nb2Os, and / or TiO2in an amount such that the ratio of (CaO + SrO + BaO) / (Nb2Os + TiO2) is greater than or equal to 0.45, greater than or equal to 0.475, or greater than or equal to 0.50 (in wt.%).

[0120] For reasons such as environmental impact, color, and / or cost, some oxides (e.g., PbO, MoO3, and GeO2) can be undesirable. Some oxides (e.g., Al2O3, Y2O3, and Ta2O5) can be undesirable in high amounts in the glass due to their ability to reduce the glass-forming ability of the glass composition. In some embodiments, the sum of Y2O3, GeO2, Ta2O5, Al2O3, MoO3, PbO, TeO2, FeO, and Fe2O3 (Y2O3+ GeO2+ Ta2O5+ Al2O3+ MoO3+ PbO+ TeO2+ FeO+ Fe2O3) is 0.0 mol% to 0.5 mol%. In some embodiments, the glass is free or substantially free of Y2O3, GeO2, Ta2O5, Al2O3, MoO3, PbO, TeO2, FeO, and Fe2O3 such that the sum of Y2O3+ GeO2+ Ta2O5+ Al2O3+ MoO3+ PbO+ TeO2+ FeO+ Fe2O3 is 0.0 mol%.

[0121] In some embodiments, the glasses of the present disclosure can be free or substantially free of fluorine. In some embodiments, the glasses can comprise 0.0 atomic % to 1.0 atomic % fluorine. For example, the glasses can comprise 0.0 atomic % to 1.0 atomic %, 0.0 atomic % to 0.5 atomic %, 0.0 atomic % to 0.25 atomic %, or 0.0 atomic % to 0.1 atomic % fluorine.

[0122] In some embodiments, the glasses of the present disclosure can be free or substantially free of at least one of PbO, GeO2, TeO2, WO3, Y2O3, and Li2O. In other embodiments, the glasses can be free or substantially free of all of PbO, GeO2, TeO2, WO3, Y2O3, and Li2O.

[0123] In some embodiments, the glasses are free or substantially free of at least one of antimony, arsenic, fluorine, Bi2O3, and PbO. For example, the glasses can be free or substantially free of PbO and Bi2O3. In another example, the glasses of the present disclosure can be free or substantially free of arsenic and / or antimony. In another example, the glasses are free or substantially free of at least one of antimony, arsenic, fluorine, Bi2O3, and PbO.

[0124] In some embodiments, Bi2O3and / or PbO can be absent or present in an amount such that the sum of Bi2O3plus PbO (Bi2O3+ PbO) is 0.0 mol% to 20.0 mol%. For example, Bi2O3and / or PbO can be absent or present in an amount such that (Bi2O3+ PbO) is: 0.0 mol% to 20.0 mol%, 0.0 mol% to 15.0 mol%, 0.0 mol% to 10.0 mol%, 0.0 mol% to 5.0 mol%, 0.0 mol% to 1.0 mol%, 1.0 mol% to 20.0 mol%, 1.0 mol% to 15.0 mol%, 1.0 mol% to 10.0 mol%, 1.0 mol% to 5.0 mol%, 5.0 mol% to 20.0 mol%, 5.0 mol% to 15.0 mol%, 5.0 mol% to 10.0 mol%, or 10.0 mol% to 20.0 mol%. In the case of higher concentrations of Bi2O3and PbO, the density of the formed glass can increase to above 4.5 g / cm3 3 Further, Bi2O3and PbO can be undesirable due to cost and / or environmental considerations, and thus it is preferred that the combined amount of Bi2O3and / or PbO be less than 20.0 mol%. In some embodiments, the glass can be free or substantially free of one or both of Bi2O3and PbO.

[0125] In some embodiments, V2O5and / or PbO can be absent or present in an amount such that the sum of V2O5plus PbO (V2O5+ PbO) is 0.0 wt% to 1.0 wt% (in wt%). For example, the sum of (V2O5+ PbO) can be 0.0 wt% to 1.0 wt%, 0.1 wt% to 1.0 wt%, or 0.5 wt% to 1.0 wt% in wt%. In some embodiments, the glass can be free or substantially free of one or both of V2O5and PbO.

[0126] According to another embodiment of the disclosure, the glass is free or substantially free of Fe, Cu, Co, Ni, and Cr. The contribution of these elements causes the glass to have an undesirable color, and thus in some embodiments, the glass is free or substantially free of coloring agents, such as: Fe, Cu, Co, Ni, and Cr.

[0127] According to embodiments of the disclosure, the glasses described herein have a refractive index nD d measured at 587.56 nm. In some examples, the glass has a refractive index nD d: greater than or equal to 1.70, greater than or equal to 1.75, greater than or equal to 1.80, greater than or equal to 1.83, greater than or equal to 1.85, greater than or equal to 1.88, greater than or equal to 1.90, measured at 587.56 nm. In some examples, the glass has a refractive index n d : 1.70 to 1.95, 1.70 to 1.90, 1.70 to 1.85, 1.70 to 1.83, 1.70 to 1.80, 1.70 to 1.75, 1.75 to 1.95, 1.75 to 1.90, 1.75 to 1.85, 1.75 to 1.83, 1.75 to 1.80, 1.80 to 1.95, 1.80 to 1.90, 1.80 to 1.85, 1.80 to 1.83, 1.85 to 1.95, or 1.85 to 1.90, measured at 587.56 nm.

[0128] At a given refractive index, a lower density corresponds to a lighter weight for an optical element using the glass. Size and weight can be important for many types of optical devices, particularly portable optical devices such as augmented reality systems. As described above, the glasses of the present disclosure have a combination of high refractive index and low density. According to embodiments of the present disclosure, the glasses described herein have a density of 4.5 g / cm 3 or less, measured at 25 °C. In some examples, the glasses of the present disclosure can have a density of 4.5 g / cm 3 or less, 4.4 g / cm 3 or less, 4.3 g / cm 3 or less, 4.2 g / cm 3 or less, 4.1 g / cm 3 or less, 4.0 g / cm 3 or less, measured at 25 °C.

[0129] In some embodiments, the glasses of the present disclosure can be characterized by a refractive index n d and a density d RT :

[0130] (n d -1) / d RT ≥ 0.205 (III)

[0131] where the refractive index n d is measured at a wavelength of 587.56 nm, and the density is measured at 25 °C (in units of g / cm 3 ). In some embodiments, the glasses of the present disclosure can be characterized by a refractive index n d and a density d RT :

[0132] n d - (1.11 + 0.18*d RT ) > 0 (IV)

[0133] wherein the refractive index n d has a value of 1.7 to 1.95 (measured at a wavelength of 587.56 nm), and a density measured at 25 °C (in units of g / cm 3 ). In some embodiments, the glasses of the present disclosure can satisfy equation (IV)(a) and / or (IV)(b) as follows:

[0134] n d - (1.120 + 0.18*d RT ) > 0 (IV)(a)

[0135] n d - (1.135 + 0.18*d RT ) > 0 (IV)(b).

[0136] The desired optical dispersion of a glass can vary depending on the particular application. The lower the optical dispersion of a glass, the larger the Abbe number v d , which corresponds to a lower degree of scattering of light by the glass. Lower optical dispersion is particularly desirable in applications where light is focused at different wavelengths in the same lens. In other applications (e.g., wavelength dispersive spectroscopy), higher optical dispersion can be desirable. According to embodiments of the present disclosure, the glasses described herein can be characterized as having low optical dispersion. As discussed above, optical dispersion can be numerically represented by the Abbe number v d . According to embodiments of the present disclosure, the glasses described herein have low optical dispersion, characterized by an Abbe number v d of 35 or less. For example, the glasses can have an Abbe number v d of 35 or less, or 33 or less. In some embodiments, for glasses having a refractive index higher than 1.8, the optical dispersion can be considered acceptably low if the Abbe number v d is greater than or equal to about 25. For example, the glasses of the present disclosure can have an Abbe number v d of 25 to 35, 25 to 33, 25 to 31, 25 to 30, 25 to 28, 25 to 27, 27 to 35, 27 to 33, 27 to 31, 27 to 30, 27 to 28, 28 to 35, 28 to 33, 28 to 31, 28 to 30, 30 to 35, 30 to 33, 30 to 31, 31 to 35, or 31 to 33.

[0137] Figure 1The refractive indices n of some comparative glasses from a number of optical company catalogs (Schott AG, Hoya, Ohara, and Sumita) as well as an exemplary glass according to the present disclosure (Exemplary Glass 12 ("Example 12"), described below in Table 6) are shown below in Table 1. d as a function of Abbe number v d ("Abbe chart"). Figure 1 The glasses shown present a challenge to form glasses with high refractive index, low density, and low optical dispersion (i.e., high Abbe number). In general, as the refractive index of a glass increases, the density of the glass also typically increases. Given a refractive index, conventional wisdom in the art suggests that a glass with lower optical dispersion (i.e., higher Abbe number) will have a higher density. In some embodiments, the glasses of the present disclosure can provide a compromise between high refractive index, low density, and low optical dispersion, which can be useful in some optical applications.

[0138] In some optical applications (e.g., camera lenses and bifocal eyeglass lenses), it is desirable to correct for the distortion of an optical image formed by an optical element (e.g., a lens). To address these challenges, some optical systems can include multiple optical elements made of optical materials having different refractive indices and dispersions, such as achromatic systems. In some applications, the optical dispersion of the preferred materials satisfies a particular relationship. One common relationship is referred to as the "normal line" and characterizes the relationship between the refractive indices of a sample at four different wavelengths (n d (587.56 nm), n F (486.1 nm), n C (656.3 nm), and n g (435.8 nm)) as follows:

[0139]

[0140] where the values of the coefficients A and B in the present disclosure are those provided by Dr. Ralf Jedamzik in "Color correction in optical systems," Schott Advanced Optics, May 2014, where A = 0.6438 and B = -0.001682. g-F refers to the partial relative dispersion. g-F The calculated values of P Figure 2P g-F vs. Abbe number v d for comparative glasses from optical catalogs of Schott AG, Hoya Corp., Ohara Corp., and Sumita Corp. and some example glasses according to the present disclosure ("Example Glasses"). Figure 2 shows the relationship of comparative and example glasses to a "standard line," shown as a line according to the equation y = 0.6438 - 0.001682*x. Figure 2 The examples shown demonstrate the challenge of forming glasses that align with the standard line, i.e., glasses that have minimal deviation or separation from the standard line.

[0141] According to some embodiments of the present disclosure, the glasses described herein can have a relative partial dispersion P g-F :

[0142] P g-F <0.6750 - 0.0028*v d (VI)

[0143] and

[0144] -0.005 < P g-F - (0.6438 - 0.001682*v d ) < 0.005 (VII)

[0145] where the Abbe number is about 33 or less.

[0146] In some embodiments, the glass is characterized as having high transmittance. Generally, the higher the transmittance of the glass, the longer the optical path transmitted for a given optical loss, which can improve optical performance in many applications. High-refractive-index glasses typically contain materials that absorb at least a portion of optical light (e.g., TiO2 and Nb2O5), particularly light in the blue and near-UV regions of the electromagnetic spectrum. In embodiments of this disclosure, the transmittance of the glass can be characterized by different wavelengths in the range of about 300 nm to about 2300 nm. In some applications, high transmittance in the visible and near-UV ranges (blue light region) is particularly desirable. Achieving high transmittance in blue light in high-refractive-index glasses can be challenging. High levels of TiO2 and / or Nb2O5 typically used in glasses to increase the refractive index tend to reduce transmittance in the near-UV region and shift the UV cutoff to higher wavelengths. For internal transmittance in blue light (considering Fresnel loss), a sample with a thickness of 10 mm is considered acceptable when it has an internal transmittance of 90% or greater at a wavelength of 460 nm; good when it has an internal transmittance of 95% or greater; and excellent when it has an internal transmittance of 97% or greater.

[0147] Figure 3 The refractive index n of comparative example glasses from the optical catalogs of Schott AG, Hoya, and Ohara, as well as some exemplary glasses (exemplary glasses) according to embodiments of this disclosure, are given. d With internal transmittance Abbe number τ int The functional relationship graph was obtained from comparative and exemplary glass samples with a thickness of 10 mm. Figure 3 The data shown was measured at a wavelength of 400 nm. Figure 3 As shown, the blue light transmittance of glass typically decreases as the refractive index increases above 1.7, 1.8, etc. Without wishing to be limited by any theory, it is believed that the addition of substances often intended to form glass with low density (e.g., TiO2 and Nb2O5) may negatively impact the glass's ability to transmit blue light. Therefore, as discussed above, in some embodiments of this disclosure, the amount of TiO2 and / or Nb2O5 in the glass can be limited as described herein, particularly when it is desirable to increase blue light transmittance.

[0148] Figure 4 This is a schematic representation of the functional relationship between total transmittance and wavelength for specific transmittance values ​​(i.e., 5%, 70%, and 80%). The wavelength corresponding to each of these specific transmittance values ​​(5%, 70%, and 80%) is denoted as λ. 5％ , λ 70％ and λ 80％In the context of the present disclosure, a decrease in the value of λ 5％ , λ 70％ , and λ 80％ corresponds to an improvement in the blue and UV transmittance of the optical glass.

[0149] In some embodiments of the present disclosure, the glass can have a total transmittance of 70% at a wavelength λ 70％ (nanometers) according to equation (VIII) below and / or according to equation (IX) below:

[0150] λ 70％ ≤ (580 * n d ) - 691 (VIII)

[0151] λ 70％ ≤ (580 * n d ) - 680 (IX)

[0152] where n d is the refractive index measured at a wavelength of 587.56 nm and the total transmittance is measured for a sample having a thickness of 10 mm.

[0153] In some embodiments of the present disclosure, the glass can have a total transmittance of 70% at a wavelength λ 70％ (nanometers) based on the relative partial dispersion P g-F of the glass according to equation (X) below:

[0154] λ 70％ ≤ 210 + 300 * P g-F (X)

[0155] where P g-F is the relative partial dispersion of the glass as described above with respect to equation (V).

[0156] In some embodiments of the present disclosure, the glass can have a total transmittance of 80% at a wavelength λ 80％ (nanometers) according to equation (XI) below:

[0157] λ 80％ ≤ (1100 * n d ) - 1620 (XI).

[0158] According to one embodiment, when measured at 360 nm using a glass sample with a thickness of 10 mm, the glass of this disclosure can have a total transmittance τ greater than or equal to 10%. For example, when measured at 360 nm using a glass sample with a thickness of 10 mm, the glass can have a total transmittance τ greater than or equal to 10%, greater than or equal to 12%, greater than or equal to 15%, or greater than or equal to 18%. In some examples, when measured at 360 nm using a glass sample with a thickness of 10 mm, the glass of this disclosure can have a total transmittance τ of 10% to 20%, 10% to 18%, 10% to 15%, or 10% to 12%. In some embodiments, when measured at 370 nm using a glass sample with a thickness of 10 mm, the glass can have a total transmittance τ greater than or equal to 25%. For example, when measured at 370 nm through a glass sample with a thickness of 10 mm, the glass may have a total transmittance τ of: greater than or equal to 25%, greater than or equal to 28%, greater than or equal to 30%, or greater than or equal to 32%. In some examples, when measured at 370 nm through a glass sample with a thickness of 10 mm, the glass of this disclosure may have a total transmittance τ of: 25% to 35%, 25% to 32%, 25% to 30%, or 25% to 28%. In some embodiments, when measured at 380 nm through a glass sample with a thickness of 10 mm, the glass may have a total transmittance τ of: greater than or equal to 50%, greater than or equal to 55%, or greater than or equal to 58%. For example, when measured at 380 nm using a glass sample with a thickness of 10 mm, the glass of this disclosure can have a total transmittance τ of 50% to 60%, 50% to 58%, or 50% to 55%.

[0159] According to some embodiments, the glass of this disclosure may have a transmittance index T equal to or greater than 0.485. i The transmittance index T is determined according to the following equation (XII). i :

[0160]

[0161] In the formula, each oxide listed in equation (XII) refers to the amount of oxide in the glass, expressed as mole%. In some examples, when the transmittance T according to equation (XII) i At values ​​less than 0.485, the transmittance of the glass may not be high enough for some applications. In some cases, the transmittance T according to equation (XII) is insufficient. imay be: greater than or equal to 0.485, greater than or equal to 0.500, greater than or equal to 0.550, or greater than or equal to 0.575. For example, the transmittance T according to equation (XII) can be: 0.485 to 0.600, 0.490 to 0.600, 0.500 to 0.600, 0.520 to 0.600, 0.540 to 0.600, 0.560 to 0.600, 0.580 to 0.600, 0.485 to 0.580, 0.490 to 0.580, 0.500 to 0.580, 0.520 to 0.580, 0.540 to 0.580, 0.560 to 0.580, 0.485 to 0.560, 0.490 to 0.560, 0.500 to 0.560, 0.520 to 0.560, 0.540 to 0.560, 0.485 to 0.540, 0.490 to 0.540, 0.500 to 0.540, 0.520 to 0.540, 0.485 to 0.520, 0.490 to 0.520, or 0.500 to 0.520. i may be: 0.485 to 0.600, 0.490 to 0.600, 0.500 to 0.600, 0.520 to 0.600, 0.540 to 0.600, 0.560 to 0.600, 0.580 to 0.600, 0.485 to 0.580, 0.490 to 0.580, 0.500 to 0.580, 0.520 to 0.580, 0.540 to 0.580, 0.560 to 0.580, 0.485 to 0.560, 0.490 to 0.560, 0.500 to 0.560, 0.520 to 0.560, 0.540 to 0.560, 0.485 to 0.540, 0.490 to 0.540, 0.500 to 0.540, 0.520 to 0.540, 0.485 to 0.520, 0.490 to 0.520, or 0.500 to 0.520.

[0162] In some embodiments, the glass can be characterized by a refractive index n d (587.56 nm measurement) and a transmittance index T i :

[0163] n d –(2.23–0.71*T i )≥0 (XIII)

[0164] Refractive index and density are two properties that can be predicted from glass composition. Linear regression analysis was performed on comparative glasses that are close to the exemplary glasses of the present disclosure and on some exemplary glasses to determine equations that can predict the composition dependence of the refractive index n d at 587.56 nm wavelength and the composition dependence of the glass density (in g / cm 3 ) at 25 °C. The following equations (XIV) and (XV) were obtained from the linear regression analysis and used to predict the refractive index and density of the glasses, respectively:

[0165]

[0166]

[0167] where P n is a refractive index parameter that predicts the refractive index n d of the glass at 587.56 nm wavelength, and P d is a density parameter that predicts the density (in g / cm 3The density parameter used for prediction is based on the glass composition, where each oxide listed in equations (XIV) and (XV) refers to the amount of oxide in the glass, expressed in moles.

[0168] Figure 5 The refractive index n is the measured value of some comparative example glasses (“comparative example glasses”) and exemplary glasses (“example glasses”). d (Measured at 587.56 nm) and refractive index parameter P n A graph showing the functional relationship. For example... Figure 5 The data shows that for most glasses, the refractive index parameter P n The compositional correlation has a measured refractive index n of ±0.015 units. d The error is within the specified range. Figure 6 These are the densities of some comparative and exemplary glasses (measured at 25°C, in g / cm³). 3 ) and density parameter P d A graph showing the functional relationship. For example... Figure 6 The data shows that for most glasses, the density parameter P d The compositional correlation has ±0.10 g / cm³. 3 Error within the range of the measured density. Table 1 below specifies the concentration limits for deriving equations (XIV) and (XV). Linear regression analysis used to determine equations (XIV) and (XV) randomly selected glasses as the training set for regression construction and selected glasses as the validation set to evaluate the interpolation ability within the predefined composition limits (as shown in Table 1 below), excluding irrelevant variables and outliers. An external dataset of existing glass compositions was used to evaluate the ability to predict specific properties falling outside the specified composition limits with reasonable accuracy. This process was performed iteratively to determine the optimal variables for each property of interest, corresponding to equations (XIV) and (XV). Data on comparative glass compositions used in the linear regression modeling were obtained from the publicly available SciGlass Information System database. For a refractive index n of 587.56 nm... d Specifically, the SciGlass information system database does not record the refractive index n measured at 587.56 nm. d The modeling system increases the refractive index n at 587.56 nm based on the refractive index value provided by the specific glass. d Interpolation.

[0169] Table 1: Component regions used for modeling

[0170]

[0171]

[0172] Tables 2, 3, and 4 below specify concentration limits representative of some embodiments of the disclosure.

[0173] According to embodiments, the glasses of the disclosure can have a refractive index parameter P n . For example, the glasses can have a refractive index parameter P n : 1.7 to 1.95, 1.75 to 1.95, 1.80 to 1.95, 1.85 to 1.95, 1.90 to 1.95, 1.7 to 1.90, 1.75 to 1.90, 1.80 to 1.90, 1.85 to 1.90, 1.7 to 1.85, 1.75 to 1.85, 1.80 to 1.85, 1.7 to 1.80, or 1.75 to 1.80.

[0174] According to another embodiment, the glasses of the disclosure can have a density parameter P d . For example, the glasses can have a density parameter P d : less than or equal to 4.5, less than or equal to 4.4, less than or equal to 4.3, less than or equal to 4.2, or less than or equal to 4.1.

[0175] According to one or more embodiments of the disclosure, the glasses herein can have a refractive index parameter P n and a density parameter P d that satisfy the following equation (XVI):

[0176] P n - (1.11 + 0.18*P d ) > 0.000 (XVI)

[0177] where the value of the refractive index parameter P n is 1.7 to 1.95. In some embodiments, the glasses of the disclosure can also satisfy the following equation (XIV)(a):

[0178] P n - (1.120 + 0.18*P d ) > 0.000 (XVI)(a)

[0179] and some glasses can also satisfy the following equation (XVI)(b):

[0180] P n - (1.135 + 0.18*P d ) > 0.000 (XVI)(b).

[0181] In some embodiments, the glasses of the present disclosure can have a refractive parameter, Pn, and a transmittance index, Ti, that satisfy the following equation (XVII):

[0182] P n (2.23 - 0.71 * T i ) > 0.000 (XVII)

[0183] where P n has a value of 1.75 to 1.95.

[0184] In some embodiments, the glasses can be characterized as having good glass forming ability, which can be assessed as resistance to devitrification during cooling. As discussed above, glass forming ability can be numerically measured by determining the critical cooling rate of the melt (i.e., the minimum cooling rate at which the melt forms glass without crystallization). According to one embodiment, the glasses can be characterized as having a critical cooling rate of less than or equal to 300°C / minute, and in some instances less than or equal to 100°C / minute. In some embodiments, the glasses of the present disclosure can be characterized by the ability to cool from 1100°C to 500°C in air in 2.5 minutes without crystallization. Glasses characterized as having such glass forming ability are compatible with a press molding process.

[0185] Table 2 below shows an exemplary glass A of the present disclosure according to some embodiments of the present disclosure. Table 2 identifies the combination of components according to some embodiments of the present disclosure, as well as their respective amounts. The exemplary glass A in Table 2 can include additional components according to any aspect of the present disclosure described herein.

[0186] Table 2: Exemplary Glass A

[0187]

[0188]

[0189] Table 3 below shows an exemplary glass B of the present disclosure according to some embodiments of the present disclosure. Table 3 identifies the combination of components according to embodiments of the present disclosure, as well as their respective amounts. The exemplary glass B in Table 3 can include additional components according to any aspect of the present disclosure described herein.

[0190] Table 3: Exemplary Glass B

[0191]

[0192] The exemplary glass B according to embodiments of the present disclosure can also satisfy the following equation (XVI):

[0193] Pn - (1.11 + 0.18*P d ) > 0.000 (XVI)

[0194] where P n is 1.7 to 1.95, and P n and P d are calculated according to equation (XIV) and equation (XV), respectively. The exemplary glass B can also have a transmittance index T i of 0.485 to 0.600, where T i is calculated according to equation (XII).

[0195] Table 4 below shows exemplary glasses C of the disclosure according to some embodiments of the disclosure. Table 4 identifies the component combinations according to embodiments of the disclosure and their respective amounts. The exemplary glasses C in Table 4 can include additional components according to any aspect of the disclosure described herein.

[0196] Table 4: Exemplary Glasses C

[0197]

[0198] The exemplary glasses C according to embodiments of the disclosure can optionally contain 0.0 atomic percent to 1.0 atomic percent fluorine. In some embodiments, the exemplary glasses C satisfy the following equation (XVII):

[0199] P n - (2.23 - 0.71*T i ) > 0.000 (XVII)

[0200] where P n is 1.75 to 1.95, and P n is calculated according to equation (XIV) and T i is calculated according to equation (XII). The exemplary glasses C can also have a density parameter P d of less than 4.5, where P d is calculated according to equation (XV).

[0201] Embodiments of the disclosure can provide glasses having a high refractive index n d of greater than 1.7, in some embodiments greater than 1.8; in combination with a density (measured at 25°C) of less than or less than or equal to 4.5 g / cm 3 ; optionally in combination with one or more additional desirable features. In some embodiments, the glasses of the disclosure can provide a high refractive index n dSome of the prior art silicate glasses have improved glass forming ability. These improvements in glass forming ability can simplify production, provide cost savings, and / or improve the quality of the final glass product. In some embodiments, the glasses of the present disclosure can provide comparable or improved optical dispersion, blue light transmittance, resistance to devitrification, and / or chemical durability compared to prior art glasses having similar refractive index n d and / or density properties.

[0202] Examples

[0203] The following examples illustrate various features and advantages of the present disclosure, which are not to be construed as limiting the application or the appended claims in any way.

[0204] The example glasses and comparative glasses were all prepared by melting relatively pure oxide materials. Table 5 below lists the typical uncertain elements found in some of the oxide materials used to prepare the example glasses and comparative glasses described herein.

[0205] Table 5: Oxide raw material and corresponding uncertain element levels

[0206] Raw materials Fe content (ppm) Cu content (ppm) Ni content (ppm) Cr content (ppm) Quartz <10 <1 <1 <1 Boric anhydride <10 <1 <1 <1 Titanium oxide <50 <15 <1 <5 Zirconium oxide <5 <5 <5 <5 Niobium oxide <70 <5 <5 <5 Lanthanum oxide <90 <4 <5 <5

[0207] To prepare the glass samples of Examples 1-26, 1 kg batches were prepared in a pure platinum crucible. The crucible was placed in a furnace set to 1250 °C, after which the furnace temperature was increased to 1300 °C and held at 1300 °C for 2 hours. The furnace temperature was then decreased to 1250 °C, and the glass was allowed to naturally cool to equilibrium at this temperature for 1 hour, after which it was poured onto a steel table and then annealed at Tg for 1 hour.

[0208] Some of the sample melts were also melted in a "one liter" platinum crucible heated by Joule effect. In this process, approximately 3700 g of raw materials were used. The crucible was filled in 1.5 hours at 1250 °C. The temperature was then increased to 1300 °C and held for 1 hour. During this step, the glass was continuously stirred at 60 rpm. The temperature was then decreased to 1200 °C, where it was allowed to naturally equilibrate for 30 minutes, and the stirring speed was decreased to 20 rpm. The delivery tube was heated at 1225 °C, and the glass was cast onto a cooled graphite table. The glass was formed into a rod that was approximately 25 mm thick, 50 mm wide, and 90 cm long. The resulting rod was examined by optical microscopy to check for crystallization, and was all free of crystals. The glass quality observed by optical microscopy was good, with no striae and no bubbles in the rod. The glass was placed in a lehr oven at Tg for 1 hour for a rough anneal. The rod was then placed in a static furnace at Tg for 1 hour, and then the temperature was decreased at 1 °C / min.

[0209] To prepare glass samples of exemplary glasses 27-65, about 15 grams (target material content greater than 99.99 wt%) of each sample was melted from batch raw materials in a platinum or platinum-rhodium crucible (Pt:Rh = 80:20) at a temperature of about 1300 °C for 1 hour. Two controlled cooling conditions were applied. In the first condition (referred to as the "15 minute test"), the sample was cooled from 1100 °C to 500 °C in the furnace in about 15 minutes. In the second condition (referred to as the "2.5 minute test"), the sample was cooled from 1100 °C to 500 °C in the furnace in about 2.5 minutes. Temperature readings were obtained by direct reading of the furnace temperature or using an IR camera with a calibrated scale. The first condition (15 minute test) corresponds approximately to a cooling rate of up to 300 °C / min at a temperature of 1000 °C, and the second test corresponds approximately to a cooling rate of up to 600 °C / min at a temperature of 1000 °C (close to this temperature, the cooling rate approaches a maximum). The cooling rate also decreases significantly as the temperature decreases. Typical scenarios for the first and second cooling regimes are shown in FIGS. 1 and 2, respectively. No chemical analysis was performed on the test samples, as similar samples prepared in separate melts were chemically analyzed by XRF methods (X-ray fluorescence for all oxides except B203) and by ICP methods (inductively coupled plasma mass spectroscopy for B203). These analyses gave deviations of ±2.0 mass% for the major components (e.g., Nb205) relative to the batch composition, which corresponds to less than about 1 mole%. Figure 7

[0210] Table 6 below lists the glass compositions and properties of exemplary glasses 1-65 according to embodiments of the present disclosure. Table 6 includes observations from three devitrification tests (referred to as "Devitrification Test 1," "Devitrification Test 2," and "Devitrification Test 3"). "Devitrification Test 1" involved observation of glass samples melted in 1 liter crucibles under an optical microscope (between 100x and 500x magnification). The following abbreviations "A," "B," "C," and "D" were used: no crystals were observed ("A"); a very limited number of crystals were found under the microscope, typically only 1 or 2 spots in the glass, and only at the surface, more than 98% of the surface was free of crystals ("B"); there were more crystals at the surface, but more than 90% of the glass surface was free of crystals ("C"); and there were some crystals in the bulk of the crucible, less than 90% of the glass surface was free of crystals ("D"). "Devitrification Test 2" involved the "15 minute test" cooling regime described above; an observation of "OK" was used to indicate that the glass composition passed this test. "Devitrification Test 3" involved the "2.5 minute test" cooling regime described above; an observation of "OK" was used to indicate that the glass composition passed this test. ​

[0211] Table 6: Exemplary glass compositions and properties

[0212]

[0213]

[0214]

[0215] Table 6 (continued)

[0216]

[0217]

[0218]

[0219]

[0220] Table 6 (continued)

[0221]

[0222]

[0223]

[0224] Table 6 (continued)

[0225]

[0226]

[0227]

[0228]

[0229] Table 6 (continued)

[0230]

[0231]

[0232]

[0233]

[0234] Table 6 (continued)

[0235]

[0236]

[0237]

[0238]

[0239] Table 6 (continued)

[0240]

[0241]

[0242]

[0243] Table 6 (continued)

[0244]

[0245]

[0246]

[0247]

[0248]

[0249]

[0250] The following Table 7 lists the glass compositions and properties for Comparative Glasses 1-53.

[0251] Table 7: Comparative Glass Compositions and Properties

[0252]

[0253]

[0254]

[0255]

[0256] Table 7 (continued)

[0257]

[0258]

[0259]

[0260]

[0261] Table 7 (continued)

[0262]

[0263]

[0264]

[0265]

[0266] Table 7 (continued)

[0267]

[0268]

[0269]

[0270]

[0271] Table 7 (continued)

[0272]

[0273]

[0274]

[0275]

[0276] Table 7 (continued)

[0277]

[0278]

[0279]

[0280]

[0281] Table 7 (continued)

[0282]

[0283]

[0284] The reference key for each of the comparative glasses listed in Table 7 is as follows: [1] DE 102006024805 Al (SCHOTT AG); [2] DE 4242859 A (SCHOTT GLASWERKE); [3] JP 2002173334 A (MINOLTA CO. LTD.); [4] JP 2002362939 A (MINOLTA CO. LTD.); [5] JP 2007153734 A (SCHOTT AG); [6] JPS 5950048 (OBARA OPTICAL GLASS CO.); [7] JPS 61168551 (NIPPON KOGAKU KK); [8] JPS 61232243 (OHARA KK); [9] US 2018251395 (ASAHI GLASS CO. LTD.);

[10] US 4732876 A (KABUSHIKI KAISHA OHARA);

[11] US 5288669 A (CORNING INC.);

[12] US 6121176 A (CORNING INC.);

[13] US 6187702 B1 (OHARA KK);

[14] US 6413894 B1 (HOYA CO. LTD.);

[15] US 7091145 B2 (CARL-ZEISS-STIFTUNG);

[16] US 7563738 B2 (OHARA KK);

[17] US 7598193 B2 (HOYA CO. LTD.);

[18] US 8661853 B2 (HOYA CO. LTD.);

[19] US 8728963 B2 (HOYA CO. LTD.).

[0285] Figure 8 A plot of the density parameter P versus the refractive index parameter P for some of the example glasses from Table 6 and some of the comparative glasses from Table 7 is shown in Figure 1. d The relationship between the density parameter P n and the refractive index parameter P d , respectively, is determined according to equations (XV) and (XIV), respectively. n wherein each oxide listed in the equations refers to the amount of the oxide in the glass expressed in mole %. Figure 8 All of the example glass compositions shown in Table 6 have the following characteristics (a) through (i):

[0286] (a) (Si02+ B203) < 50.0 mole %, wherein 3.0 mole % < Si02< 50.0 mole % and 18.0 mole % < B203< 33.0 mole %;

[0287] (b) 0.0 mol% < R2O + RO < 40.0 mol%, where R2O is the total content of monovalent metal oxide (e.g., alkali metal oxide) in the glass composition, and RO is the total content of divalent metal oxide (e.g., alkaline earth metal oxide, ZnO, CaO, etc.) in the glass composition.

[0288] (c) 0.0 mol% < Bi2O3+ PbO < 20.0 mol%;

[0289] (d) 0.0 mol% < TiO2< 22.0 mol%;

[0290] (e) 1.0 mol% < Nb2O5< 30.0 mol%;

[0291] (f) 1.0 mol% < ZnO < 10.0 mol%;

[0292] (g) substantially free of fluorine;

[0293] (h) a transmittance index T i > 0.485; and

[0294] (i) (Y2O3+ GeO2+ Ta2O5+ Al2O3+ MoO3+ PbO) is 0.0 mol% to 0.5 mol%.

[0295] The comparative glasses listed above were chosen among known glasses having the features (a) to (i) to have the highest refractive index parameter P d with a comparable density parameter P n with the comparative glasses having the lowest refractive index parameter P

[0296] Figure 8 The lines shown corresponding to the equations y = 1.12 + 0.18*x and y = 1.135 + 0.18*x provide a visual representation of the difference between the comparative glasses having the features (a) to (i) listed above and some of the example glasses according to the present disclosure. From Figure 8 it can be seen that Figure 8 some of the example glasses presented in Table 1 (solid circles) fall above the line y = 1.120 + 0.18*x and none of the comparative glasses (open circles) fall above the line y = 1.120 + 0.18*x, where y corresponds to the refractive index parameter P n and x corresponds to the density parameter P d In other words, Figure 8 some of the example glasses presented in Table 1 satisfy the following equation (XVI)(a) and none of the comparative glasses satisfy the following equation (XVI)(a):

[0297] P n - (1.120 + 0.18*Pd > 0.000 (XVI)(a).

[0298] From Figure 8 it can be seen that Figure 8 some of the example glasses presented in Table 1 fall above the line y = 1.135 + 0.18*x and none of the comparative glasses fall above the line y = 1.135 + 0.18*x, where y corresponds to the refractive index parameter P n and x corresponds to the density parameter P d In other words, Figure 8 some of the example glasses presented in Table 1 can satisfy the following equation (XVI)(ab) and none of the comparative glasses can satisfy the following equation (XVI)(b):

[0299] P n - (1.135 + 0.18*P d ) > 0.000 (XVI)(b).

[0300] This means that under the above defined conditions some of the example glasses from the present disclosure have a higher refractive index at comparable density than the best comparative glass satisfying conditions (a) to (i) above.

[0301] Figure 9 A graph showing the relationship between the measured density d RT (25°C measurement in g / cm 3 ) and the measured refractive index n d (587.56 nm measurement) for some of the example glasses from Table 6 and some of the comparative glasses from Table 7 is shown. Figure 9 Plotted in Table 1 are example glasses 11, 12, 15, 17 and 25 and comparative glasses C2, C3, C6, C7, C9, C14 and C23. The comparative glasses selected are distinguished in that they have the highest measured refractive index at corresponding density among those comparative glasses of Table 7 satisfying conditions (a) to (i) above.

[0302] Figure 9 The lines shown corresponding to equations y = 1.12 + 0.18*x and y = 1.135 + 0.18*x provide a visual representation of the difference between comparative glasses and example glasses according to the present disclosure. From Figure 9 it can be seen that Figure 9 some of the example glasses presented in Table 1 fall above the line y = 1.120 + 0.18*x and none of the comparative glasses fall above the line y = 1.120 + 0.18*x, where y corresponds to the measured refractive index n n and x corresponds to the measured d RTIn other words, some of the example glasses of Table 6 satisfy the following equation (IV)(a) and none of the comparative example glasses of Table 7 satisfy the following equation (IV)(a):

[0303] n d - (1.120 + 0.18 * d RT )> 0 (IV)(a).

[0304] From Figure 9 It can also be seen that Figure 9 The selected example glasses presented in Table 6 fall above the line y = 1.135 + 0.18 * x and none of the selected comparative example glasses fall above the line y = 1.135 + 0.18 * x, where y corresponds to the measured refractive index n n and x corresponds to the measured d RT In other words, some of the example glasses having properties (a) through (i) above satisfy the following equation (IV)(b) and none of the comparative example glasses having properties (a) through (i) above satisfy the following equation (IV)(b):

[0305] n d - (1.135 + 0.18 * d RT )> 0 (IV)(b).

[0306] Figure 10 A plot showing the relationship between the refractive index parameter P n and the transmittance index T i for some of the example glasses from Table 6 and some of the comparative example glasses from Table 7.

[0307] Figure 10 All of the example glass compositions shown in Table 6 have the following characteristics (a) through (u):

[0308] (a) (Si02+ B203) < 50.0 mol%, where 3.0 mol% < Si02< 50.0 mol% and B203> 1.0 mol%;

[0309] (b) (RE203+ Ti02+ Nb205+ Zr02+ Bi203+ W03) > 25.0 mol%, where RE203is the total content of rare earth metal oxides in the glass composition;

[0310] (c) (Si02+ B203+ Alk20 + MgO + CaO + SrO + BaO + ZnO) < 69.0 mol, where Alk20 is the total content of alkali metal oxides in the glass composition;

[0311] (d) RO > 3.0 mol%, where RO is the total content of divalent metal oxides (e.g., alkaline earth metal oxides, ZnO, CaO, etc.) in the glass composition;

[0312] (e) 0.5 mol% < Nb2O5< 25.0 mol%;

[0313] (f) 0.0 mol% < TiO2< 18.0 mol%;

[0314] (g) 0.0 mol% < RE2O3< 23.0 mol%;

[0315] (h) 0.0 mol% < CaO < 32.0 mol%;

[0316] (i) 0.0 mol% < BaO < 15.0 mol%;

[0317] (j) 0.0 mol% < Bi2O3< 20.0 mol%;

[0318] (k) 0.0 mol% < Li2O < 7.0 mol%;

[0319] (l) 0.0 mol% < MgO < 5.0 mol%;

[0320] (m) 0.0 mol% < HfO2< 1.0 mol%;

[0321] (n) 0.0 mol% < TeO2< 5.0 mol%;

[0322] (o) 0.0 mol% < ZnO < 2.0 mol%;

[0323] (p) 0.0 mol% < Y2O3< 1.5 mol%;

[0324] (q) 0.0 mol% < CdO < 15.0 mol%;

[0325] (r) 0.0 mol% < PbO < 1.0 mol%;

[0326] (s) 0.0 atom% < F < 1.0 atom%;

[0327] (t) 0.0 mol% < Ta2O5< 1.5 mol%; and

[0328] (u) a density parameter P d less than or equal to 4.5 and a refractive index parameter P n greater than or equal to 1.75.

[0329] Figure 10The comparative glasses shown were selected from the comparative glasses of Table 7 having the mentioned characteristics (a) to (u) in the corresponding transmittance index T i The numerical values have the highest refractive index parameter P n The numerical values.

[0330] As discussed above, the transmittance index T i is related to the blue light transmittance of the glass. Figure 10 The line shown corresponding to the equation y = 2.23 - 0.71 * x provides a visual representation of the difference between the comparative glasses and the exemplary glasses according to the present disclosure. From Figure 10 it can be seen that Figure 10 some of the exemplary glasses presented in Table 6 fall above the line y = 2.23 - 0.71 * x and none of the comparative glasses fall above the line y = 2.23 - 0.71 * x, where y corresponds to the refractive index parameter P n and x corresponds to the transmittance index T i . In other words, some of the exemplary glasses of Table 6 having the above listed characteristics (a) to (u) satisfy the following equation (XVII) and none of the comparative glasses having the above listed characteristics (a) to (u) satisfy the following equation (XVII):

[0331] P n - (2.23 - 0.71 * T i ) > 0.000 (XVII).

[0332] Figure 11 A graph showing the relationship between the measured refractive index n n (587.56 nm measurement) and the transmittance index T i is shown for some of the exemplary glasses from Table 6 and some of the comparative glasses from Table 7. Figure 11 The line shown corresponding to the equation y = 2.23 - 0.71 * x provides a visual representation of the difference between the comparative glasses and the exemplary glasses according to the present disclosure. From Figure 11 it can be seen that Figure 11 some of the exemplary glasses presented in Table 6 fall above the line y = 2.23 - 0.71 * x and none of the comparative glasses fall above the line y = 2.23 - 0.71 * x, where y corresponds to the measured refractive index n n and x corresponds to the transmittance index T i . In other words, some of the exemplary glasses of Table 6 having the above listed characteristics (a) to (u) satisfy the following equation (XIII) and none of the comparative glasses having the above listed characteristics (a) to (u) satisfy the following equation (XIII):

[0333] n d–(2.23–0.71*T i )≥0 (XIII).

[0334] This means that, under the conditions (a) to (u) specified above, some exemplary glasses from this disclosure have a relatively high transmittance index T. i In numerical cases, it has a higher refractive index than the best comparable glass under the same conditions.

[0335] Figure 12 The total transmittance τ at wavelengths from approximately 320 nm to approximately 500 nm was compared between the exemplary glass 12 according to this disclosure and several comparative example glasses (C54-C58) from Japanese Patent Application No. 2005-239506. Figure 12 As shown, exemplary glass 12 provides some transmission at wavelengths from 350 nm to 380 nm, where... Figure 12 The comparative glass shown provides almost no transmission, and in some cases, almost no to no transmission. For both exemplary glass 12 and the comparative glass, Figure 12 The total transmittance τ data shown are all obtained from glass samples with a thickness of 10 mm. Figure 12 As can be seen, the exemplary glass 12 provides the following total transmittance τ: greater than 50% at 380 nm, greater than 25% at 370 nm, and greater than 10% at 360 nm. Figure 12 The data also shows that the exemplary glass 12 provides some transmittance even at 350 nm, where the comparative glass provides almost no or nearly zero transmittance.

[0336] Figure 13 and 14 The relative partial dispersion P of some exemplary glasses and some comparative glasses is shown. g-F With Abbe number ν d The function relationship graph. Figure 13 Showing several comparative glass samples purchased from the optical catalogs of Schott AG, Hoya, Ohara, and Sumita. Figure 14 Shown are several comparative glass examples from prior art references, namely: U.S. Patents 8,647,996, 8,883,664, 8,852,745, 9,416,047, and 6,333,288; U.S. Publication No. 20160090320; German Publication No. DE 10 2006 024805; and Hong Kong Publication No. HK 1029098. Figure 13 and 14 The data shows a favorable combination of properties in some optical systems, namely: low dispersion (i.e., high Abbe number ν). dThe glass's low density and specific refractive index ratios at different wavelengths make it compatible with glasses that correct image distortions in optical systems (e.g., achromatic systems) with lower refractive indices. In such systems, it is desirable for the glass to have properties corresponding to (i.e., close to) a "standard line," as described above. Figure 13 and 14 In this context, the standard line is displayed as the line defined by the equation y = 0.6438 – 0.001682 * x.

[0337] Figure 13 and 14 The glass shown is limited to those with a measured density of less than or equal to 4.5 g / cm³. 3 Those exemplary and comparative examples of glass.

[0338] Figure 14 The glass shown is further limited to the measured refractive index n. d Exemplary and comparative glasses with a refractive index greater than or equal to 1.80 are excluded to exclude data involving lower refractive indices that would be irrelevant to applications that desire high refractive indices and are close to the standard line.

[0339] Figure 13 and 14 The text appears to be a mix of Chinese characters and symbols, possibly related to a video or video file. A direct translation wouldn't be meaningful. d The vertical line at 33.0 shows what appears to be the maximum feasible Abbe number (i.e., the lowest dispersion) that can be achieved while maintaining glass properties close to the standard line, thus P g-F The value deviates from this line by no more than ±0.005 units. For example... Figure 13 As shown, some exemplary glasses presented in the embodiments described herein have an Abbe number of ν. d The value is closer to ν compared to the comparison glass. d ν is provided in the case of =33.0 d With P g-F Combinations of attributes.

[0340] like Figure 14 As shown in the data, some exemplary glasses are able to extend the Abbe number ν of the standard line compared to comparative glass. d The feasible range. Figure 13 and 14 The data confirms some exemplary glass characterizations of this disclosure as ν d ≤33.0 and also satisfies the following equations (VII) and (VI):

[0341] -0.005≤P g-F –(0.6438–0.001682ν d )≤+0.005 (VII)

[0342] as well as

[0343] P g-F <0.6750–0.0028*ν d (VI)

[0344] As discussed above, the terms "low dispersion" and "high dispersion" are situation-specific, and in some cases, the same optical glass may be considered "high dispersion" for one application and "low dispersion" for another. In this disclosure, for a high refractive index of 1.80 or greater and 4.5 g / cm³, the term "high dispersion" is used. 3 Or lower density glass, with an Abbe number of 30-35 units. d It would be considered "low dispersion" (compared to other glasses with similar properties). However, for those with a dispersion below 4.5 g / cm³... 3 The low density and the position of the glass along the standard line, with an Abbe number of 30-35 units. d It represents the highest possible dispersion compared to other glasses located along the standard line.

[0345] like Figure 13 and 14 As shown, several exemplary glasses exhibit combinations of properties desired in many applications, which are not achievable in the comparative glass shown, namely:

[0346] (a) Quite low density (d RT ≤4.5g / cm 3 );

[0347] (b) Relatively high refractive index (n) d ≥1.80);

[0348] (c) A fairly low Abbe number (ν) d ≤33.0);

[0349] (d) Consistency with the standard line (displayed as the line y = 0.6438 – 0.001682*x); and

[0350] (e) Relatively low relative partial dispersion P given the Abbe number g-F (As evidenced by several exemplary glasses satisfying the inequality y < 0.6800 - 0.0028 * x, combined with the properties (a) to (d) listed above).

[0351] The present disclosure includes the following non-limiting aspects. To the extent not already described, the features of each of the first through fifty-sixth aspects can be combined with those of any one or more of the other aspects in the same or different combination, even though such combinations are not explicitly described herein.

[0352] Many changes and modifications can be made to the embodiments described above of the present disclosure, without departing from the spirit and scope of the present disclosure in its various aspects. All such changes and modifications are intended to be included within the scope of the present disclosure, and are to be resolved in the light of the scope of the appended claims.

[0353] To the extent not already described, the different features of each of the various aspects of the present disclosure can be used in combination with each other, according to desired configurations. Nothing in this document is to be construed as an admission that the aspects of the disclosure are not entitled to antecedent art. No admission is made that any aspect of the disclosure constitutes related art. The disclosure can be practiced with the indi- vidual features set forth and combinations of them in the general context of any one of the following, or in any other general context now known or later developed.

Claims

1. A glass comprising: Si02 from 0.3 wt% to 30.0 wt%; B203 from 0.3 wt% to 30.0 wt%; Nb205 from 0.3 wt% to 50.0 wt%; at least one oxide selected from the group consisting of Zr02, SrO, CaO, Li20, MgO, ZnO, Y203, Ta205, BaO, PbO, Ti02, Gd203, Ge02, K20, La203, and Na20, with the proviso that: Zr02 from 2.5 wt% to 15.0 wt%; CaO from 0.5 wt% to 25.0 wt%; Gd203 from 0.0 wt% to 20.0 wt%; Y203 from 0.0 wt% to 10.0 wt%; Ti02 from 2 wt% to 5 wt%; ZnO from 0.0 wt% to 2.0 wt%; Li20 from 0.0 wt% to 2.0 wt%; Ge02 from 0.0 wt% to 2.0 wt%; Ta205 from 0.0 wt% to 1.0 wt%; and wherein the glass is further defined in terms of wt% of oxides as: the sum of (Nb205 + Ti02) from 18.0 wt% to 50.0 wt%; the sum of (Si02 + B203) from 1.0 wt% to 30.0 wt%; the sum of (La203 + Gd203) from 0.0 wt% to 40.0 wt%; the sum of (CaO + SrO + BaO) is 0.2 wt% or greater; the sum of (PbO + V205) from 0.0 wt% to 1.0 wt%; the ratio of CaO / (Li20 + Na20 + K20 + MgO + CaO + SrO + BaO + ZnO) is 0.50 or greater; the ratio of (Si02 / (Si02 + B203)) is greater than 0.0 to less than or equal to 0.50; and the ratio of (CaO + SrO + BaO) / (Nb205 + Ti02) is 0.45 or greater, and wherein, the glass is substantially free of fluorine.

2. The glass of claim 1, wherein, The glass is characterized by the ability to cool from 1100°C to 500°C in air in 2.5 minutes without crystallization.

3. A glass comprising: Si02 from 3.0 mole% to 50.0 mole%; B203 from 18.0 mole% to 33.0 mole%; Nb205 from 1.0 mole% to 30.0 mole%; and at least one oxide selected from the group consisting of W03, Zr02, SrO, CaO, Li20, MgO, ZnO, Y203, Ta205, BaO, CdO, Bi203, PbO, Hf02, Te02, Ti02, Al203, Gd203, Ge02, K20, La203, Na20, M0O3, FeO, Fe203, and Yb203, with the proviso that: Ti02 from 0.0 mole% to 22.0 mole%; ZnO from 0.0 mole% to 10.0 mole%; the sum of (Si02 + B203) from 3.0 mole% to 50.0 mole%; the sum of (Y2O3 + GeO2 + Ta2O5 + Al2O3 + MoO3 + PbO + TeO2 + FeO + Fe2O3) is 0.0 mol% to 0.5 mol%; the sum of the total content of divalent metal oxides RO and the total content of alkali metal oxides Alk2O (RO + Alk2O) is 0.0 mol% to 40.0 mol%; and the sum of (Bi2O3 + PbO) is 0.0 mol% to 20.0 mol%; and wherein the glass is substantially free of fluorine, and wherein the glass satisfies the following equation (XVI): P n - (1.11 + 0.18*P d ) ≥ 0.000 (XVI) in which P n is a refractive index parameter having a value of 1.7 to 1.95 and is calculated according to equation (XIV) below: wherein P d is a density parameter calculated according to the following equation (XV): and wherein the glass has a transmittance index T of 0.485 to 0.600 i wherein T i is calculated according to the following equation (XII): and each oxide listed in equation (XIV), equation (XV), and equation (XII) refers to the amount of the oxide in the glass expressed as mol%.

4. The glass of claim 3, wherein, the glass has: 1.7 to 1.95 refractive index n d , wherein n d is the refractive index measured at a wavelength of 587.56 nm; and Density d RT in g / cm 3 at 25°C, and wherein the density d is determined according to the following method: wherein the glass satisfies the following equation (IV): n d - (1.11 + 0.18*d RT ) ≥ 0 (IV).

5. The glass of claim 3, wherein, the glass is characterized by the ability to cool from 1100°C to 500°C in air in 2.5 minutes without crystallization.

6. The glass of claim 3, wherein, The glass also has an Abbe number v of 33 or less d and satisfies the following equation (VI) and the following equation (VII): P g-F <0.6750–0.0028*ν d (VI) and -0.005 < P g-F - (0.6438 - 0.001682*ν d ) < 0.005 (VII) where P g-F is the relative partial dispersion of the glass and is calculated according to the following equation (II): P g-F = (n g – n f ) / (n f – n c ) (II) where n g is the refractive index measured at 435.8 nm, n F is the refractive index measured at 486.1 nm, and n c is the refractive index measured at 656.3 nm.

7. The glass of claim 3, wherein, The glass also comprises a density d according to the following equation (III) RT and a refractive index n d : (n d - 1) / d RT ≥ 0.205 (III) wherein d RT is the density measured at 25°C in g / cm 3 and n d is the refractive index measured at a wavelength of 587.56 nm.

8. A glass comprising: SiO2 is 3.0 mol% or more; B2O3 is 1.0 mol% or more; Nb2O5 is 0.5 mol% to 25.0 mol%; the total content of divalent metal oxides RO is 3.0 mol% or more; and at least one oxide selected from the group consisting of WO3, ZrO2, SrO, CaO, Li2O, MgO, ZnO, Y2O3, Ta2O5, BaO, CdO, Bi2O3, PbO, HfO2, TeO2, TiO2, Al2O3, Gd2O3, GeO2, K2O, La2O3, Na2O, and Yb2O3, with the proviso that: CaO is 0.0 mol% to 32.0 mol%; Li2O is 0.0 mol% to 7.0 mol%; MgO is 0.0 mol% to 5.0 mol%; Y2O3 is 0.0 mol% to 1.5 mol%; Ta2O5 is 0.0 mol% to 0.5 mol%; BaO is 0.0 mol% to 12.0 mol%; CdO is 0.0 mol% to 10.0 mol%; Bi2O3 is 0.0 mol% to 20.0 mol%; PbO is 0.0 mol% to 1.0 mol%; HfO2 is 0.0 mol% to 5.0 mol%; TeO2 is 0.0 mol% to 5.0 mol%; TiO2 is 0.0 mol% to 18.0 mol%; ZnO is 0.0 mol% to 2.0 mol%; fluorine is 0.0 atomic% to 1.0 atomic%; the total content of alkaline earth metal oxides RE2O3 is 0.0 mol% to 23.0 mol%; the sum of (RE2O3 + TiO2 + Nb2O5 + ZrO2 + Bi2O3 + WO3) is 25.0 mol% or more; the sum of (SiO2 + B2O3) is greater than 0.0 mol% to 50.0 mol%; and the sum of (SiO2 + B2O3 + Alk2O + MgO + CaO + SrO + BaO + ZnO) is 4.0 mol% to 69.0 mol%, where Alk2O is the total content of alkali metal oxides, and wherein the glass satisfies the following equation (XVII): P n - (2.23 - 0.71 * T i ) ≥ 0.000 (XVII) wherein P is a refractive index parameter having a value of 1.75 to 1.95, and wherein the refractive index parameter P is calculated according to equation (XIV) below: n wherein P is a refractive index parameter having a value of 1.75 to 1.95, and wherein the refractive index parameter P is calculated according to equation (XIV) below: n wherein P is a refractive index parameter having a value of 1. where T i The transmittance index of the glass was calculated according to equation (XII) as follows: and wherein the glass has a density parameter P less than 4.5 d wherein the density parameter P d is calculated according to equation (XV) below: And each oxide listed in equation (XIV), equation (XV) and equation (XII) refers to the amount of the oxide in the glass, expressed as a mole %.

9. The glass of claim 8, wherein, The glass also has a refractive index n d and wherein the refractive index n d and the transmittance index T i satisfies the following equation (XIII): n d - (2.23 - 0.71 * T i ) ≥ 0 (XIII) wherein n d is the refractive index measured at a wavelength of 587.56 nm.

10. The glass of claim 8, wherein, The glass also has an Abbe number v of 33 or less d and satisfies the following equation (VI) and the following equation (VII): P g-F <0.6750–0.0028*ν d (VI) and -0.005 < P g-F - (0.6438 - 0.001682*ν d ) < 0.005 (VII) where P g-F is the relative partial dispersion of the glass and is calculated according to the following equation (II): P g-F = (n g – n F ) / (n F – n C ) (II) where n g is the refractive index measured at 435.8 nm, n F is the refractive index measured at 486.1 nm, and n C is the refractive index measured at 656.3 nm.

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