Copper-containing near-infrared absorbing glass composition and products comprising the same for filter applications

Abstract

Copper containing near-infrared absorbing glass compositions, articles comprising the same, methods of making the same, and methods of using the same are provided. Such glass compositions include in mole percent on an oxide basis and by a fluorine content: P2O5: 30-40; SiO2: 0-10; K2O: 0-15; ZnO: 15-40; CaO: 0-12; SrO: 0-20; MgO: 0-10; BaO: 0-12; CuO: 4-18; Al2O3: 1-7; Li2O: 1-20; Na2O: 0-10; Sb2O3: 0-5; and total fluorine (F): 1-60. The combined concentration of RO is in a range from 20 to 40, and the combined concentration of R'2O is in a range of from 2 to 18. RO is selected from MgO, CaO, SrO, BaO, and ZnO, and R'2O is selected from Li2O, Na2O, and K2O. The glass compositions have red-shifted cutoff wavelength and good transmittance of visible light and good absorbance in near-infrared wavelength ranges and are suitable for use as an optical filter for a camera.

Description

COPPER-CONTAINING NEAR-INFRARED ABSORBING GLASS COMPOSITIONAND PRODUCTS COMPRISING THE SAME FOR FILTER APPLICATIONSPRIORITY CLAIM AND CROSS-REFERENCE

[0001] This application claims the benefit of priority under 35 U.S.C. § 119 of U.S. Provisional Application No. 63 / 723,327 filed November 21, 2024, and U.S. Provisional Application No. 63 / 619,856 filed January 11, 2024, the content of each of which is incorporated herein by reference in its entirety.FIELD

[0002] The disclosure relates to glass compositions generally. More particularly, the disclosed subject matter relates to glass compositions having near-infrared (NIR) properties and suitable for use in light filter applications; articles comprising the glass compositions; and methods for making the same.BACKGROUND

[0003] Many light sources, including the sun, emit infrared and near-infrared (NIR) light. An IR or NIR filter, which is a color filter blocking the infrared or NIR light, are required in a color camera to achieve realistic colors in white light. The color spectrum seen by the human eye is quite limited compared to the spectrum seen by a charged-coupled device (CCD) camera. In the near infrared region of the spectrum, the difference in sensitivity is more significant. A CCD color camera in daylight without an IR filter will therefore see a significant amount of infrared light resulting in strange colors. An IR filter cuts away a significant amount of the overall collected light and thereby affects the sensitivity in a negative way.

[0004] The spectral sensitivity of solid-state imaging elements such as CCDs employed in digital cameras runs from visible range to near-infrared range around 1,200 nm. Accordingly, filters absorbing light in near-infrared range are employed to obtain images approximating the visible sensitivity of humans.SUMMARY

[0005] The present disclosure provides a glass composition, a product comprising such a glass composition, methods of making the glass composition and the product, and methods of using the glass composition and the product. Such a glass composition is a nearinfrared (NIR) absorbing glass. Such glass compositions exhibit desirable optical performance and durability as described herein. The glass compositions are suitable for use as an optical filter in camera applications.

[0006] In one aspect, the present disclosure provides a glass or a glass composition. In accordance with some embodiments, a glass or a glass composition provided herein comprises in mole percent on an oxide basis and by a fluorine content:P2O5: 30-40;SiO2: 0-10;K2O: 0-15;ZnO: 15-40;CaO: 0-12;SrO: 0-20;MgO: 0-10;BaO: 0-12;CuO: 4-18;AI2O3: 1-7;Li2O: 1-20;Na2O: 0-10;Sb2O3: 0-5; and total fluorine (F): 1-60; wherein a combined concentration of RO is in a range from 20 to 40, a combined concentration of R’2O is in a range of from 2 to 18, RO is selected from the group consisting of MgO, CaO, SrO, BaO, and ZnO, and R’2O is selected from the group consisting of Li2O, Na2O, and K2O.

[0007] In some embodiments, AI2O3, CuO, MgO, CaO, SrO, BaO, ZnO, Li2O, Na2O, and K2O may be partially fluorinated, and the related oxide contents can be referred as oxide equivalents as described in the Detailed Description.

[0008] In some embodiments, the total fluorine is in a suitable range. For example, the total fluorine is in a range of from 1 to 60 by mole percent, in a range of from 15 to 60 by mole percent, in a range of from 20 to 60 by mole percent, in a range of from 25 to 55 by mole percent, in a range of from 25 to 50 by mole percent, in a range of from 30 to 60 by mole percent, in a range of from 30 to 55 by mole percent, in a range of from 30 to 50 by mole percent, or any other suitable range.

[0009] In some embodiments, P2O5 is in a suitable range. For example, P2O5 is in a range of from 30 to 40 by mole percent, in a range of from 30 to 39 by mole percent, in a range of from 30 to 38 by mole percent, in a range of from 30 to 37 by mole percent, in a range of from 31 to 39 by mole percent, in a range of from 31 to 38 by mole percent, in a range of from 31 to 37 by mole percent, in a range of from 32 to 39 by mole percent, in a range of from 32 to 38 by mole percent, in a range of from 32 to 37 by mole percent, or any other suitable range.

[0010] In some embodiments, CuO is in a suitable range. For example, CuO is in a range of from 4 to 18 by mole percent, in a range of from 5 to 18 by mole percent, in a range of from 4 to 17 by mole percent, in a range of from 5 to 17 by mole percent, in a range of from 6 to 16 by mole percent, in a range of from 6 to 15 by mole percent, in a range of from 6 to 14 by mole percent, in a range of from 6 to 13 by mole percent, in a range of from 6 to 12 by mole percent, in a range of from 6 to 11 by mole percent, in a range of from 6 to 10 by mole percent, or any other suitable range.

[0011] In some embodiments, RO is in a suitable range. For example, the combined concentration of RO is in a range of from 20 to 40 by mole percent, in a range of from 21 to 39 by mole percent, in a range of from 21 to 38 by mole percent, in a range of from 22 to 38 by mole percent, in a range of from 23 to 38 by mole percent, in a range of from 23 to 37 by mole percent, in a range of from 23 to 36 by mole percent, in a range of from 23 to 35 by mole percent, in a range of from 24 to 35 by mole percent, in a range of from 25 to 35 by mole percent, in a range of from 26 to 35 by mole percent or any other suitable range.

[0012] In some embodiments, RO is selected from ZnO only, a combination of ZnO and SrO, and a combination of ZnO, SrO and BaO.

[0013] In some embodiments, ZnO is in a suitable range. For example, ZnO is in a range of from 15 to 40 by mole percent, in a range of from 16 to 39 by mole percent, in a range of from 16 to 38 by mole percent, in a range of from 16 to 36 by mole percent, in a range of from 16 to 35 by mole percent, in a range of from 17 to 35 by mole percent, in a range of from 17 to 34 by mole percent, in a range of from 17 to 33 by mole percent, in arange of from 17 to 32 by mole percent, in a range of from 17 to 31 by mole percent, in a range of from 17 to 30 by mole percent, or any other suitable ranges.

[0014] In some embodiments, SrO is in a suitable range. For example, SrO is in a range of from 0 to 20 by mole percent, in a range of from 1 to 19 by mole percent, in a range of from 2 to 18 by mole percent, in a range of from 3 to 18 by mole percent, in a range of from 4 to 17 by mole percent, in a range of from 5 to 16 by mole percent, in a range of from 5 to 15 by mole percent, in a range of from 5 to 14 by mole percent, in a range of from 5 to 13 by mole percent, in a range of from 5 to 12 by mole percent, or any other suitable ranges.

[0015] In some embodiments, BaO is in a suitable range. For example, BaO is in a range of from 0 to 12 by mole percent, in a range of from 0 to 11 by mole percent, in a range of from 0 to 10 by mole percent, in a range of from 0 to 9 by mole percent, in a range of from 0 to 8 by mole percent, in a range of from 0 to 7 by mole percent, or any other suitable ranges.

[0016] In some embodiments, R’20 is in a suitable range. For example, the combined concentration of R^O is in a range of from 2 to 18 by mole percent, in a range of from 2 to 17 by mole percent, in a range of from 2 to 16 by mole percent, in a range of from 3 to 15 by mole percent, in a range of from 4 to 14 by mole percent, in a range of from 5 to 16 by mole percent, in a range of from 5 to 14 by mole percent, in a range of from 6 to 14 by mole percent, or any other suitable range.

[0017] In some embodiments, R^O is selected from Li2O and K2O and may be substantially free of Na2O.

[0018] In some embodiments, Li2O is in a suitable range. For example, Li2O is in a range of from 1 to 20 by mole percent, in a range of from 2 to 19 by mole percent, in a range of from 2 to 18 by mole percent, in a range of from 2 to 17 by mole percent, in a range of from 2 to 16 by mole percent, in a range of from 2 to 15 by mole percent, in a range of from 3 to 15 by mole percent, in a range of from 3 to 14 by mole percent, in a range of from 3 to 13 by mole percent, in a range of from 3 to 12 by mole percent, in a range of from 3 to 11 by mole percent, in a range of from 3 to 10 by mole percent, or any other suitable range.

[0019] In some embodiments, K2O is in a suitable range. For example, K2O is in a range of from 0 to 15 by mole percent, in a range of from 1 to 15 by mole percent, in a range of from 1 to 14 by mole percent, in a range of from 2 to 14 by mole percent, in a range of from 3 to 13 by mole percent, in a range of from 3 to 12 by mole percent, in a range of from 4 to 12 by mole percent, in a range of from 5 to 12 by mole percent, or any other suitable range.

[0020] In some preferred embodiments, the glass or the glass composition comprises in mole percent on the oxide basis and by the fluorine content:P2O5: 31-38;SiO2: 0-8;K2O: 4-12;ZnO: 16-35;CaO: 1-4;SrO: 3-18;MgO: 0-4;BaO: 0-10;CuO: 5-17;AI2O3 : 2-6;Li2O: 2-15;Na2O: 0-5;Sb2O3: 0-4; and total fluorine (F): 20-60; wherein the combined concentration of RO is in a range from 22 to 38, the combined concentration of R’2O is in a range of from 4 to 16.

[0021] In some more preferred embodiments, the glass or the glass composition comprises in mole percent on the oxide basis and by the fluorine content:P2O5: 32-37;SiO2: 0-6;K2O: 5-12;ZnO: 17-30;CaO: 2-3;SrO: 5-12;MgO: 0-2;BaO: 0-7;CuO: 6-10;AI2O3 : 3-6;Li2O: 3-10;Na2O: 0-2.5;Sb2O3: 0-3; andtotal fluorine (F): 30-50; wherein the combined concentration of RO is in a range from 26 to 35, the combined concentration of R’20 is in a range of from 6 to 14.

[0022] In some embodiments, the glass is substantially free of Sb20s, which can be replaced with SnO2.

[0023] In some embodiments, the glass may further comprise Y2O3. Its concentration may be in range of from 0 to 1.6 mol%.

[0024] The glass and glass composition described herein have good optical performance. For example, the glass has a red-shifted cutoff wavelength with at least 50% transmittance at a thickness of 0.21 mm being at least 635 nm or longer. At the thickness of 0.21 mm, the glass has a transmittance higher than 85% at wavelengths in a range of 425-465 nm, a transmittance higher than 87% at wavelengths in a range of 466-560 nm, a transmittance lower than 5% at wavelengths in a range of 750-800 nm, and a transmittance lower than 10 % at a wavelength of 1,200 nm.

[0025] The glass and glass composition also have good durability. For example, a change in the transmittances is lower than 1% after the glass is exposed to 85 °C / 85% relative humidity (RH) for 120 hours.

[0026] In another aspect, a method for producing the glass or the glass composition as described herein is provided. Such a method comprises at least one step of mixing and melting raw materials in mole percent on an oxide basis and by the fluorine content so as to provide the oxides as described. Such a method may further comprise making a sheet comprising the glass composition through a suitable process. Examples of the raw material as the source for the total fluorine include, but are not limited to, AIF3, CaF2, SrF2, BaF2, ZnF2, and any combination thereof.

[0027] In another aspect, the present disclosure provides an article comprising the glass or the glass composition described herein. For example, an optical filter such as NIR filter comprises the glass or the glass composition described here. The filter is used for camera applications.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not necessarily to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Like reference numerals denote like features throughout specification and drawings.

[0029] FIG. 1 shows the transmittance spectra of 0.21 mm thick polished samples of Ca-free composition (Example 10) and Ca-containing compositions (Examples 13-15).

[0030] FIG. 2 shows the transmittance spectra of 0.21 mm thick polished samples of glass with the higher alkali (R2O) concentration (Example 3) and lower alkali concentration (Example 7).

[0031] FIG. 3 shows the transmittance spectra of 0.21 mm thick polished samples of a low P2O5 composition (Example 6 with 35 mol% of P2O5) and a high P2Os-containing composition (Example 35 with 50 mol% of P2O5.)

[0032] FIG. 4 shows the transmittance spectra of 0.2 mm thick polished parts of Examples 44-51.

[0033] FIG. 5 shows the transmittance spectra of 0.21 mm thick polished glass samples of Example 52 having a higher antimony (Sb2O3) content and Example 53 having lower Sb2O3content.

[0034] FIG. 6 shows the transmittance spectra of parts 0.21 mm thick polished glass samples of Examples of 61-63, which comprise 0, 4 mol%, and 8 mol% of Li2O, respectively.

[0035] FIG. 7 shows the transmittance of Example 81 at a thickness of 0.21 mm before and after 120-hr exposure to 85 °C / 85% RH.

[0036] FIG. 8 shows the transmittance of Example 87 at a thickness of 0.21 mm before and after 120-hr exposure to 85 °C / 85% RH.

[0037] FIG. 9 shows the percent change in transmittance measured before and after the exposure for Example 81.

[0038] FIG. 10 shows the percent change in transmittance measured before and after the exposure for Example 87.

[0039] FIG. 11 shows the transmittance spectra of 0.21 mm thick polished samples of Example 88-93.

[0040] FIG. 12 shows the transmission spectra for Examples 94 and 95 melted with O2 bubbling compared to Example 87 melted in air.

[0041] FIG. 13 shows the transmission spectra for single and double melt based on composition of Example 94, wherein the O2 bubbling was applied at the second step of the double melts.

[0042] FIG. 14 shows the transmission spectra for Examples 96-99 compared to Example 87.

[0043] FIG. 15 shows the transmission spectra for Examples 102-104 compared to Example 87.DETAILED DESCRIPTION

[0044] This description of the exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivative thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the apparatus be constructed or operated in a particular orientation. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.

[0045] For purposes of the description hereinafter, it is to be understood that the embodiments described below may assume alternative variations and embodiments. It is also to be understood that the specific articles, compositions, and / or processes described herein are exemplary and should not be considered as limiting.

[0046] Open terms such as “include,” “including,” “contain,” “containing” and the like mean “comprising.” These open-ended transitional phrases are used to introduce an open-ended list of elements, method steps or the like that does not exclude additional, unrecited elements or method steps. It is understood that wherever embodiments are described with the language “comprising,” otherwise analogous embodiments described in terms of “consisting of’ and / or “consisting essentially of’ are also provided.

[0047] The transitional phrase “consisting of’ and variations thereof excludes any element, step, or ingredient not recited, except for impurities ordinarily associated therewith.

[0048] The transitional phrase “consists essentially of,” or variations such as “consist essentially of’ or “consisting essentially of’ excludes any element, step, or ingredient not recited except for those that do not materially change the basic or novel properties of the specified method, structure or composition.

[0049] In the present disclosure the singular forms “a,” “an,” and “the” include the plural reference, and reference to a particular numerical value includes at least that particular value, unless the context clearly indicates otherwise. When values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. As used herein, “about X” (where X is a numerical value) preferably refers to ±10% of the recited value, inclusive. For example, the phrase “about 8” preferably refers to a value of 7.2 to 8.8, inclusive. Where present, all ranges are inclusive and combinable. For example, when a range of “1 to 5” is recited, the recited range should be construed as including ranges “1 to 4”, “1 to 3”, “1-2”, “1-2 & 4-5”, “1-3 & 5”, “2-5”, and the like. In addition, when a list of alternatives is positively provided, such listing can be interpreted to mean that any of the alternatives may be excluded, e.g., by a negative limitation in the claims. For example, when a range of “1 to 5” is recited, the recited range may be construed as including situations whereby any of 1, 2, 3, 4, or 5 are negatively excluded; thus, a recitation of “1 to 5” may be construed as “1 and 3-5, but not 2”, or simply “wherein 2 is not included.” It is intended that any component, element, attribute, or step that is positively recited herein may be explicitly excluded in the claims, whether such components, elements, attributes, or steps are listed as alternatives or whether they are recited in isolation.

[0050] The terms “substantial,” “substantially,” and variations thereof as used herein are intended to note that a described feature is equal or approximately equal to a value or description. Moreover, “substantially similar” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially similar” may denote values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

[0051] In some embodiments, the glass described herein may have any suitable shape. Examples of a glass include, but are not limited to, a flat or curved glass article such as an optical filter.

[0052] Unless expressly indicated otherwise, the term “glass article” or “glass” used herein is understood to encompass any object made wholly or partly of glass. Glass articles include monolithic substrates, glass substrates with a coating thereon, or laminates of glass and glass, glass and non-glass materials, glass and crystalline materials, and glass and glass-ceramics (which include an amorphous phase and a crystalline phase). Unless expressly indicated otherwise, the terms “glass” and “glass composition” used herein may be interchangeable.

[0053] Exemplary glass articles include, but are not limited to, a filter comprising a composition as described herein.

[0054] In the embodiments of the glass compositions described herein, the concentrations of constituent components (e.g., SiCh, CuO, and the like) are specified in mole percent (mol. %) on an oxide basis, unless otherwise specified.

[0055] The terms “free” and “substantially free,” when used to describe the concentration and / or absence of a particular constituent component in a glass composition, means that the constituent component is not intentionally added to the glass composition. However, the glass composition may contain traces of the constituent component as a contaminant or tramp in amounts of less than 0.03 mol.% or less than 0.01 mol. %.

[0056] The term “softening point,” as used herein, refers to the temperature at which the viscosity of the glass composition is 1 * IO76poise.

[0057] The term “annealing point,” as used herein, refers to the temperature at which the viscosity of the glass composition is 1 x 1013poise.

[0058] The terms “strain point” and “Tstrain” as used herein, refers to the temperature at which the viscosity of the glass composition is 3* 1014poise.

[0059] The liquidus temperature of a glass (Tiiq) is the temperature (°C) above which no crystalline phases can coexist in equilibrium with the glass. The liquidus viscosity is the viscosity of a glass at the liquidus temperature.

[0060] The term “CTE,” as used herein, refers to the coefficient of thermal expansion of the glass composition over a temperature range from about room temperature (RT) to about 300° C. The linear coefficient of thermal expansion (CTE) over the temperature range 25-300° C is expressed in terms of x 107 / ° C, and determined following ASTM standard E228.

[0061] Young’s modulus values and shear modulus in terms of GPa, and Poisson's ratio were determined using a resonant ultrasonic spectroscopy technique of the general type set forth in ASTM E1875-00el. The terms “Young’s modulus” and “elastic modulus” may be interchangeable.

[0062] The fracture toughness may be measured using known methods in the art, for example, using a chevron notch, short bar, notched beam and the like, according to ASTMC1421-10, “Standard Test Methods for Determination of Fracture Toughness of Advanced Ceramics at Ambient Temperature.”

[0063] Glass obtained by adding CuO to phosphate glass has been employed as filter glass, but phosphate glass has drawbacks such as poor weatherability and a tendency to develop surface roughness and clouding when exposed to high temperature and high humidity for extended periods. Thus, near-infrared light-absorbing filter glass having a basic composition in the form of fluorophosphate glass comprising a fluorine component and having good weatherability is developed as described herein.

[0064] The present disclosure provides glass compositions, products such as articles or devices comprising the same, and method for making the glass composition and the products. The glass compositions are copper-containing and low P2O5 fluorophasphate glasses. The glass compositions have a red-shifted cutoff wavelength and superior weatherability and can be used as NIR filter glass for cameras.

[0065] The glass is used as an NIR filter and is placed directly in front of a camera detector or image sensor in a CCD camera. Such a glass must provide high visible transmittance and strong absorption of near-infrared (NIR) wavelengths. In addition, the glass filter must be resistant to corrosion in hot and / or humid environments. The NIR filter, which may comprise the glass disclosed herein, alone or in combination with a coating. Without any NIR filter, the image collected may exhibit a pink hue. When the NIR filer comprising the glass is used, the image is redder in color, as it is to the human eye as it is supposed to be.

[0066] The need for NIR attenuation arises because the detector sensitivity spans the UV, VIS, and NIR regimes. When images are collected in low-ambient light conditions in the presence of a heat source that emits NIR (e.g., a stove or campfire) or a material that radiates NIR (e.g., black fabric), the detector becomes saturated with these longer wavelengths. This causes the color saturation of the image to be poor. With an appropriately designed NIR filter, color saturation can be improved by reducing the relative amount of NIR wavelengths that reach the detector.

[0067] During the extensive research and development, the inventors used a set of criteria to develop and choose good glass compositions.

[0068] For the optical property requirements, a good near-infrared light-absorbing glass needs to exhibit good transmission, based on a thickness of 0.21 mm, in the spectral transmittance of wavelengths of 400 to 700 nm, i.e., a high visible transmittance. The glass needs to provide a wavelength, at which a 50 percent transmittance is exhibited, is 635 nm orlonger. Such a wavelength (“635 nm / T50%”) is referred as a red-shifted cutoff wavelength. The glass provides a transmittance at a wavelength shorter than the cutoff wavelength is higher than 50 percent, and a transmittance at a wavelength longer than the cutoff wavelength is less than 50 percent. For example, the glass needs to provide a transmittance higher than 85% at wavelengths in a range of 425-465 nm, and a transmittance higher than 87% at wavelengths in a range of 466-560 nm. For another example, the glass needs to provide a transmittance lower than 10 % at a wavelength of 1,200 nm, and a transmittance lower than 5% at wavelengths in a range of 750-800 nm. The low transmittance requirement is referred as “high NIR absorbance.”

[0069] Good weatherability is required to withstand long-term use. When weatherability is poor, fogging occurs on the surface of the glass and it cannot be employed in applications such as optical filters. Weatherability is tested by maintaining an optically polished glass sample at 85 °C and a relative humidity (RH) of 85% for 120 hours and up to 1,000 hours, and then measuring the transmittance of the glass. After the exposure to 85 °C / 85% RH, the change in transmittance of the glass needs to be less than 1%.

[0070] It is extremely difficult to meet these challenging requirements. To achieve the high near-infrared (NIR) absorbance and red-shifted cutoff wavelength (635 nm / T50%), it is necessary to introduce >15 mol% Cu2+in an optimized base glass. Silicates and aluminates cannot generally solubilize such high concentrations of copper oxide.Additionally, the Cu2+absorbance in silicates, aluminates, and borates is too blue-shifted to achieve the targeted a 635 nm cutoff wavelength and maintain the low NIR transmittance.

[0071] Phosphate glasses can be used to solubilize large concentrations of transition metal ions and can accommodate the >15 mol% Cu2+required to achieve the desired NIR attenuation. In these glasses, P2O5 concentration directly influences the peak position of the Cu2+absorbance and the durability. As a trend, the higher the P2O5 concentration, the more red-shifted the Cu2+absorbance becomes. For glasses with “high” Cu2+concentration (>15 mol%), they must contain at least 50 mol% P2O5 to achieve the targeted redshifted 635 nm cutoff wavelength. If the P2O5 concentration decreases below 50%, the Cu2+absorbance is too blue shifted.

[0072] Like the peak position of the Cu2+absorbance, the chemical durability, specifically weathering in 85 °C / 85% RH, of these glasses, scales directly with P2O5 concentration. Glasses with “good durability” defined as <1% change in transmittance after 120-1000 hours in 85 °C / 85% RH, must have P2O5 concentrations below 37 mol%. At P2O5 concentrations much higher than 37 mol%, the durability can be improved in a several ways,such as increasing the AI2O3 concentration or introducing Fe20s. However, in Cu-doped glasses, the presence of alumina increases the Cu1+population, causing reduced visible transmittance, as do Fe3+cations. Cu2+is preferred for the desired optical performance. Accordingly, at the highest alumina concentration such as between 3 and 6 mol% that enable them to meet the visible transmittance requirement, the P2O5 concentration must be maintained at or below 37 mol% to achieve the targeted weathering performance.

[0073] The approach that has been identified to date to make a bulk glass meeting the 635 nm cutoff wavelength, the optical transmittance, and the durability requirements as described herein, without the use of a coating to improve durability, is to utilize a composition with a “low” P2O5 concentration such as < 40%, preferably <38 mol%, more preferably <37 mol%, and reduce the copper oxide concentration to <18%, preferably <17 mol%, more preferably <10 mol%.

[0074] Consequently, this decreases the NIR absorbance of the glass, but it is a necessary trade-off to achieve the other targeted attributes. As described herein, the chemical durability and the optical properties of these novel and inventive glasses is largely based upon the appropriate concentrations of P2O5, AI2O3, SiCh, and the ratios of alkali and alkaline-earth cations. Appropriate use of oxidizing agents and melting profile greatly influence the resultant optical properties of these glasses and our best practices are described herein.

[0075] The present disclosure provides a glass composition, a product comprising such a glass composition, methods of making the glass composition and the product, and methods of using the glass composition and the product. The glass compositions exhibit desirable physical and chemical properties, for example, optical performance and weathering resistance as described herein. The glass compositions are suitable for use as an optical filter for camera applications.

[0076] In one aspect, the present disclosure provides a glass or a glass composition and an article comprising the same. In accordance with some embodiments, a glass or a glass composition provided herein comprises the ingredients in mole percent on an oxide basis (except fluorine) as shown in Table 1.

[0077] Table 1. Compositional ranges of an exemplary composition

[0078] The total fluorine content (in mol%) is the molar sum of the fluorine from all fluorinated species in a glass composition. In the Examples described herein, the fluorine sources used include, but are not limited to, AIF3, CaF2, SrF2, BaF2, ZnF2, or a combination thereof. These fluorides are also the sources of the corresponding oxides. The fluorine may be combined with Al, Mg, Ca, Sr, Ba, Cu, Zn, Li, Na, and K. Each corresponding oxide of Al, Ca, Sr, Ba, Cu, Zn, Li, Na, and K listed in Table 1 (also in Tables 2-3) is referred as corresponding “oxide equivalent” or “equivalent of oxide,” which refers to the oxide basis to the maximum oxidation level based on the content of the corresponding metal selected from the group of Al, Mg, Ca, Sr, Ba, Cu, Zn, Li, Na, and K. For the oxide equivalents of Al, Ca, Sr, Ba, Cu, Zn, Li, Na, and K, the oxides may be partially replaced with fluorine. So, the corresponding oxide equivalent may include both the corresponding oxide and the corresponding fluoride of the same metal. In some embodiments, the fluorination may occur proportionally among these species.

[0079] No fluorination occurs to P2O5, SiCL, and Sb2O3. The contents of P2O5, SiCL, and Sb2O3listed in Tables 1-3 and in the tables of examples are on oxide basis. Even if the term “oxide equivalent” is used with respect to P2O5, SiCE, and Sb2O3, the content of the oxide equivalent is the same as the content of the corresponding oxide.

[0080] The content of “RO” or “R,” in the present disclosure refers to the sum of oxide equivalents of Mg, Ca, Sr, Ba, and Zn, wherein R is selected from Mg, Ca, Sr, Ba, and Zn. The content of total “R2O” refers to the sum of oxide equivalents of alkali metals, where R’ is selected from Li, Na, and K.

[0081] In some embodiments, for the oxides, RO is selected from the group consisting of MgO, CaO, SrO, BaO, and ZnO, and R’20 is selected from I 2O, Na2O, and K2O.

[0082] In some embodiments, RO is selected from ZnO only, a combination of ZnO and SrO, and a combination of ZnO, SrO and BaO.

[0083] In some embodiments, ZnO is in a suitable range. For example, ZnO is in a range of from 15 to 40 by mole percent, in a range of from 16 to 39 by mole percent, in a range of from 16 to 38 by mole percent, in a range of from 16 to 35 by mole percent, in a range of from 17 to 35 by mole percent, in a range of from 17 to 34 by mole percent, in a range of from 17 to 33 by mole percent, in a range of from 17 to 32 by mole percent, in a range of from 17 to 31 by mole percent, in a range of from 17 to 30 by mole percent, or any other suitable ranges.

[0084] In some embodiments, SrO is in a suitable range. For example, SrO is in a range of from 0 to 20 by mole percent, in a range of from 1 to 19 by mole percent, in a range of from 2 to 18 by mole percent, in a range of from 3 to 18 by mole percent, in a range of from 4 to 17 by mole percent, in a range of from 5 to 16 by mole percent, in a range of from 5 to 15 by mole percent, in a range of from 5 to 14 by mole percent, in a range of from 5 to 13 by mole percent, in a range of from 5 to 12 by mole percent, or any other suitable ranges.

[0085] In some embodiments, BaO is in a suitable range. For example, BaO is in a range of from 0 to 12 by mole percent, in a range of from 0 to 11 by mole percent, in a range of from 0 to 10 by mole percent, in a range of from 0 to 9 by mole percent, in a range of from 0 to 8 by mole percent, in a range of from 0 to 7 by mole percent, or any other suitable ranges.

[0086] In some embodiments, R^O is in a suitable range. For example, the combined concentration of R^O is in a range of from 2 to 18 by mole percent, in a range of from 2 to 17 by mole percent, in a range of from 2 to 16 by mole percent, in a range of from 3 to 15 by mole percent, in a range of from 4 to 14 by mole percent, in a range of from 5 to 16 by mole percent, in a range of from 5 to 14 by mole percent, in a range of from 6 to 14 by mole percent, or any other suitable range.

[0087] In some embodiments, R^O is selected from I 2O and K2O and may be substantially free of Na2O. No sodium-containing raw material is added.

[0088] In some embodiments, Li2O is in a suitable range. For example, Li2O is in a range of from 1 to 20 by mole percent, in a range of from 2 to 19 by mole percent, in a range of from 2 to 18 by mole percent, in a range of from 2 to 17 by mole percent, in a range offrom 2 to 16 by mole percent, in a range of from 2 to 15 by mole percent, in a range of from 3 to 15 by mole percent, in a range of from 3 to 14 by mole percent, in a range of from 3 to 13 by mole percent, in a range of from 3 to 12 by mole percent, in a range of from 3 to 11 by mole percent, in a range of from 3 to 10 by mole percent, or any other suitable range.

[0089] In some embodiments, K2O is in a suitable range. For example, K2O is in a range of from 0 to 15 by mole percent, in a range of from 1 to 15 by mole percent, in a range of from 1 to 14 by mole percent, in a range of from 2 to 14 by mole percent, in a range of from 3 to 13 by mole percent, in a range of from 3 to 12 by mole percent, in a range of from 4 to 12 by mole percent, in a range of from 5 to 12 by mole percent, or any other suitable range.

[0090] In some embodiments, the total fluorine is in a suitable range. For example, the total fluorine is in a range of from 1 to 60 by mole percent, in a range of from 10 to 60 by mole percent, in a range of from 20 to 60 by mole percent, in a range of from 25 to 55 by mole percent, in a range of from 25 to 50 by mole percent, in a range of from 30 to 60 by mole percent, in a range of from 30 to 55 by mole percent, in a range of from 30 to 50 by mole percent, or any other suitable range.

[0091] In some embodiments, P2O5 is in a suitable range. For example, P2O5 is in a range of from 30 to 40 by mole percent, in a range of from 30 to 39 by mole percent, in a range of from 30 to 38 by mole percent, in a range of from 30 to 37 by mole percent, in a range of from 31 to 39 by mole percent, in a range of from 31 to 38 by mole percent, in a range of from 31 to 37 by mole percent, in a range of from 32 to 39 by mole percent, in a range of from 32 to 38 by mole percent, in a range of from 32 to 37 by mole percent or any other suitable range.

[0092] In some embodiments, CuO is in a suitable range. For example, CuO is in a range of from 4 to 18 by mole percent, in a range of from 5 to 18 by mole percent, in a range of from 4 to 17 by mole percent, in a range of from 5 to 17 by mole percent, in a range of from 6 to 16 by mole percent, in a range of from 6 to 15 by mole percent, in a range of from 6 to 14 by mole percent, in a range of from 6 to 13 by mole percent, in a range of from 6 to 12 by mole percent, in a range of from 6 to 11 by mole percent, in a range of from 6 to 10 by mole percent, or any other suitable range.

[0093] In some embodiments, RO is in a suitable range. For example, the combined concentration of RO is in a range of from 20 to 40 by mole percent, in a range of from 21 to 39 by mole percent, in a range of from 21 to 38 by mole percent, in a range of from 22 to 38 by mole percent, in a range of from 23 to 38 by mole percent, in a range of from 23 to 37 by mole percent, in a range of from 23 to 36 by mole percent, in a range of from 23 to 35 bymole percent, in a range of from 24 to 35 by mole percent, in a range of from 25 to 35 by mole percent, in a range of from 26 to 35 by mole percent or any other suitable range.

[0094] In some preferred embodiments, a glass or a glass composition provided herein comprises the ingredients in mole percent on an oxide basis (except fluorine) as shown in Table 2.

[0095] Table 2. Preferred Compositions in some embodiments

[0096] In some more preferred embodiments, a glass or a glass composition provided herein comprises the ingredients in mole percent on an oxide basis (except fluorine) as shown in Table 3.

[0097] Table 3. More preferred compositions in some embodiments

[0098] The ranges listed in Tables 1-3 should be understood to include any narrower numerical ranges within a specified range. For example, for the RO content, the range of from 20-40 % listed in Table 1 is not limited to 22-38% listed in Table 2 and 26-35 % listed in Table 3 only. The range of from 20-40 % includes, but is not limited to, 20-39%, 20-38%, 20-37%, 20-36%, 20-35%, 21-39%, 21-38%, 21-37%, 21-36%, 21-35%, and any other ranges within the range of 20-40%.

[0099] The compositions are substantially free of B, Ce, and Cl in accordance with some embodiments. The compositions may be free of MgO in some embodiments.

[0100] In some embodiments, the total R2O concentration be greater than about 9 mol% and equal to or lower than 13 mol%. The total R2O concentration higher than 13 mol% is not favorable in some embodiments, as it promotes lower visible transmittance and strongly blue-shifted cutoff wavelengths.

[0101] The R2O identity plays a role in chemical durability and optical transmittance of the resulting glass compositions. Li2O is more favorable than K2O, which is more favorable relative to Na2O. In some embodiments, the compositions are also substantially free of Na.

[0102] In some embodiments, the Li2O concentration is at least 2 mol%, for example, in a range of 2-15%, and more preferably in a range of 3-10 mol% such as in a range of 3-7 mol%.

[0103] The total RO concentration be in a range of 20-40 mol%, for example, in a range of 22-38 mol%, in range of 26-35 mol%, or in a range of 25-30 mol%.

[0104] The ZnO content may be in a range of from 17 mol% to 30 mol%. This range can be good for silica-free compositions in some embodiments. With the addition of silica, the ZnO concentration may be slightly lower.

[0105] In some embodiments, the RO identity is preferably selected from ZnO only, a combination of ZnO+SrO, and a combination of ZnO+SrO+BaO. It is more preferable to use the combination of ZnO+SrO+BaO, where ZnO is equal to or higher than 17 mol%.

[0106] BaO should be kept below 10 mol% and more preferably be below 7.5 mol%, and most preferably below 5 mol% in combination with ZnO+SrO to ensure good durability. In such a combination, ZnO is at least 17 mol% and Sr is at least 4 mol% in some embodiments.

[0107] In some embodiments, the glass is substantially free of Mg. No Mg- containing material is added.

[0108] The P2O5 concentration may be in the range of 30-40 mol%. In some embodiments, a lower P2O5 is preferred for durability. However, to redshift the cutoff wavelength, maximizing the P2O5 concentration is favorable, but durability must be sacrificed. In some embodiments, the P2O5 concentration is preferable to be below 38 mol% and more preferably be below 37%, and most preferably between 34 mol% and 36 mol%.

[0109] Sb2O3is used optionally as a fining agent, but other chemical fining agents could also be employed to obtain glass of sufficient quality. For example, exemplary glasses could employ any one or combinations of SnCh, AS2O3, CeCh, Fe2O3, and halides as deliberate additions to facilitate fining, and any of these could be used in conjunction with the Sb2O3chemical fining agent shown in the examples. In some embodiments, Sb2O3may be replaced with tin oxide (e.g. SnCh).

[0110] Fe2O3may be introduced to increase visible absorbance and improve durability in the range of 0.1 mol% to about 3 mol%. Titania may be used to increase Young’s modulus of the glass at concentrations of 0.25 mol% to about 5 mol%.[Oi l 1] In some embodiments, the glass is substantially free of Sb2O3, which can be replaced with SnCh.

[0112] In some embodiments, the glass may further comprise Y2O3. Its concentration may be in range of from 0 to 1.6 mol%.

[0113] The glass and glass composition described herein have good optical performance. For example, the glass has a red-shifted cutoff wavelength with at least 50% transmittance at a thickness of 0.21 mm being at least 635 nm or longer. At the thickness of 0.21 mm, the glass has a transmittance higher than 85% at wavelengths in a range of 425-465 nm, a transmittance higher than 87% at wavelengths in a range of 466-560 nm, a transmittance lower than 5% at wavelengths in a range of 750-800 nm, and a transmittance lower than 10 % at a wavelength of 1,200 nm.

[0114] The glass and glass composition also have good durability. For example, a change in the transmittances is lower than 1% after the glass is exposed to 85 °C / 85% relative humidity (RH) for 120 hours.

[0115] In another aspect, a method for producing the glass or the glass composition as described herein is provided. Such a method comprises at least one step of mixing and melting raw materials in mole percent on an oxide basis and by the fluorine content so as to provide the oxides as described. Such a method may further comprise making a sheet comprising the glass composition through a suitable process. Examples of the raw material as the source for the total fluorine include, but are not limited to, AIF3, CaF2, SrF2, BaF2, ZnF2, and any combination thereof.

[0116] In another aspect, the present disclosure provides an article comprising the glass or the glass composition described herein. For example, an optical filter such as NIR filter comprises the glass or the glass composition described here. The filter is used for camera applications.

[0117] In the present disclosure, the bulk glass having the compositions as descried can satisfy the challenging requirements. It is optionally to use an additional coating in combination with the glass compositions.

[0118] EXAMPLES

[0119] The following examples are set forth below to illustrate the methods and results according to the disclosed subject matter. These examples are not intended to be inclusive of all embodiments of the subject matter disclosed herein, but rather to illustrate representative methods and results. These examples are not intended to exclude equivalents and variations of the present disclosure which are apparent to one skilled in the art.

[0120] Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for. Unless indicated otherwise, temperature is in °C or is at ambient temperature, and pressure is at or near atmospheric. The compositions themselves are given in mole percent on an oxide basis and have been normalized to 100%. There are numerous variations and combinations of reaction conditions, e.g., component concentrations, temperatures, pressures and other reaction ranges and conditions that can be used to optimize the product purity and yield obtained from the described process. Only reasonable and routine experimentation will be required to optimize such process conditions.

[0121] The glass properties set forth in tables were determined in accordance with techniques conventional in the glass art. Thus, the linear coefficient of thermal expansion (CTE) over the temperature range 25-300 °C is expressed in terms of x 10'7 / °C and the annealing point is expressed in terms of °C. These were determined from fiber elongationtechniques (ASTM references E228-85 and C336, respectively). The density in terms of grams / cm3was measured via the Archimedes method (ASTM C693). The melting temperature in terms of °C (defined as the temperature at which the glass melt demonstrates a viscosity of 200 poises) was calculated employing a Fulcher equation fit to high temperature viscosity data measured via rotating cylinders viscometry (ASTM C965-81).

[0122] The viscosity of the glass at high temperatures is measured in accordance with ASTM C965-96 (2012), titled “Standard Practice for Measuring Viscosity of Glass Above the Softening Point.” As used herein, the “Vogel-Fulcher-Tamman” (VFT) relation describes the temperature dependence of the viscosity and is represented by the following equation: logr[=A+ B T-To where r^ is viscosity. To determine VFT A, VFT B, and VFT To, the viscosity of the glass composition is measured over a given temperature range. The raw data of viscosity versus temperature is then fit with the VFT equation by least-squares fitting to obtain A, B, and To. With these values, a viscosity point (e.g., 200 Poise (P) Temperature, 35,000 P Temperature, and 200,000 P Temperature) at any temperature above softening point may be calculated.

[0123] The liquidus temperature of the glass in terms of °C was measured using the standard gradient boat liquidus method of ASTM C829-81. This involves placing crushed glass particles in a platinum boat, placing the boat in a furnace having a region of gradient temperatures, heating the boat in an appropriate temperature region for 24 hours, and determining by means of microscopic examination the highest temperature at which crystals appear in the interior of the glass. More particularly, the glass sample is removed from the Pt boat in one piece and examined using polarized light microscopy to identify the location and nature of crystals which have formed against the Pt and air interfaces, and in the interior of the sample. Because the gradient of the furnace is very well known, temperature vs. location can be well estimated, within 5-10 °C. The temperature at which crystals are observed in the internal portion of the sample is taken to represent the liquidus of the glass (for the corresponding test period). Testing is sometimes carried out at longer times (e.g. 72 hours), to observe slower growing phases. The liquidus viscosity in poises was determined from the liquidus temperature and the coefficients of the Fulcher equation.

[0124] Young's modulus values and shear modulus in terms of GPa, and Poisson's ratio were determined using a resonant ultrasonic spectroscopy technique of the general type set forth in ASTM El875~00el.

[0125] Described herein is a new series of IOW-P2O5 fluorophosphate near-infrared absorbing “blue” filter glasses that can achieve the targeted cutoff wavelength (635 nm) andmeet the 120-hour durability requirement in 85 °C / 85% RH at the specified 0.21 mm thickness. Also described is a method of making these glasses, which is important for achieving the targeted optical attributes.

[0126] These glasses offer improved weathering performance relative to the incumbent materials when subjected to prolonged durations of time at 85 °C / 85% RH.

[0127] As described herein, these glasses require very specific ranges and ratios of species to deliver the targeted cutoff wavelength and meet the weatherability requirement. These different ranges and ratios, as well as the process required to make these glasses, are described herein. Composition tables are for the as-batched material in mole percent (mol %).

[0128] 1. Raw materials, Processes, and Resulting compositions

[0129] The exemplary glasses in the tables were prepared using a commercial sand as a silica source, milled such that 90% by weight passed through a standard U.S. 100 mesh sieve. Alumina and / or aluminum metaphosphate (A1(PO3)3) was used as the source for alumina.

[0130] Phosphorous pentoxide, phosphoric acid liquid, a phosphate salt, or a mixture thereof was used as a source for phosphorous pentoxide (P2O5). In the Examples described herein, the batching of P2O5 as anhydrous solid was avoided. Its liquid acid form was also avoided or minimized. Anhydrous P2O5 is incredibly reactive and hygroscopic and leads to clumping and exothermic reactions with some of the other raw materials. Liquid phosphoric acid is also very reactive and requires a calcining step prior to melting which can lead to foaming and other complications. For these reasons, phosphate-based batch materials for most other species were used.

[0131] Boron phosphate (BPO4) was used for the source for boron oxide (B2O3).

[0132] Lithium metaphosphate was used as the source for lithium oxide (Li2O). Sodium -hexametaphosphate was used as the source for sodium oxide (Na2O). Potassium nitrate, potassium carbonate, potassium phosphate monobasic, or a mixture thereof was used as the source for potassium oxide (K2O).

[0133] Monomagnesium phosphate (Mg(H2PO4)2) was used for the source of magnesium oxide (MgO). Monocalcium phosphate anhydrous (Ca(H2PO4)2), calcium carbonate, or a mixture thereof was used for the source of calcium oxide. Strontium oxide was used for the source for strontium oxide. Barium metaphosphate, barium dihydrogen phosphate, barium nitrate, or a mixture thereof was used as the source for BaO.

[0134] Zinc pyrophosphate (Zn2P2O?), zinc oxide, or a mixture thereof was used as the source for ZnO.

[0135] Copper (II) phosphate, copper (II) metaphosphate, or a mixture thereof was used as the source for oxide of copper such as CuO.

[0136] The salts of phosphate, metaphosphate, and pyrophosphate are also additional sources for phosphorous pentoxide (P2O5).

[0137] Examples of suitable sources used for fluorine (or fluoride) include, but are not limited to, aluminum fluoride (AIF3), calcium fluoride (CaF2), strontium fluoride (SrF2), barium fluoride (BaF2), zinc fluoride (ZnF2), or a combination thereof. These fluorides used may also provide the corresponding oxides. The fluorine may be combined with Al, Ca, Sr, Ba, Cu, Zn, Li, Na, and K. Flurorination may be proportionally distributed among these species in some embodiments. No fluorine is combined with P2O5, SiCL, and Sb20s.

[0138] In the Examples described herein, the fluorine sources used include, but are not limited to, AIF3, CaF2, SrF2, BaF2, ZnF2, or a combination thereof. These fluorides also provide the corresponding oxides. In the tables showing the compositions of the Examples, the amount of one or more fluorides used are presented for the convenience of description. The one or more fluorides used should be considered as the sources for both corresponding oxides and fluorinated counterpart. For example, referring to Table 4, when barium fluoride and zinc fluoride were used as the ingredient for fluorination, the amount listed for the fluorides in the tables of the Examples such as Table 4 was the actual amount of each fluoride used. The fluorine may be combined with Al, Ca, Sr, Ba, Cu, Zn, Li, Na, and K. For the metals such as Al, Ca, Sr, Ba, and Zn in the fluorine source(s) used, the total amount of a corresponding oxide equivalent should include the amount of the metal fluoride used. For example, referring to Example 1, 15 mol.% of ZnF2 was used as the source of fluorine, while 11 mol.% of ZnO is also shown in Table 4. The total amount of the ZnO equivalent is 26 mol.% while 26 mol.% of ZnO may be partially fluorinated. For the oxide equivalents of Al, Ca, Sr, Ba, Cu, Zn, Li, Na, and K, the oxides may be partially replaced with fluorine.

[0139] Antimony (III) oxide was used the source for Sb2O3.

[0140] The raw materials were thoroughly mixed, loaded into a platinum vessel suspended in a furnace heated by silicon carbide glowbars, melted and stirred for several hours at temperatures between 700 and 1300 °C to ensure homogeneity, and delivered through an orifice at the base of the platinum vessel. The resulting patties of glass were annealed at or near the annealing point, and then subjected to various experimental methods to determine physical, viscous and liquidus attributes.

[0141] Mixing of batch materials was conducted by turbula mixing, sometimes with media, and sometimes by ball milling for times ranging from 0.25-24 hours. To minimize changes in the oxidation state of copper, all melts were made in quartz crucibles that were fitted with lids to prevent volatilization of fluorine, phosphorous, and other species. Melts were made at temperatures between 700-1,300 °C for times ranging from 2-24 hours in ambient air electric ovens. Sometimes the atmosphere over the melt was controlled using a ‘cover gas’ comprised of at least one of the following: nitrogen, argon, oxygen. Melts were homogenized by mechanical stirring or agitation. Melts were cast onto steel and other metal tables, molds, and annealed at temperatures ranging from 325-600 °C. Glasses were also cast onto graphite plates and ramps to promote faster cooling.

[0142] Melts can be made in other crucible types such as alumina or platinum. Alumina uptake can decrease the Cu2+population and is therefore not recommended for the melting of these filter glasses.

[0143] To emphasize the importance of temperature and also validate that these copper-rich phosphate glasses can be melted in platinum, a series melts were made of the composition of Example 88 in a platinum crucible at three different temperatures, including 900 °C, 1,000 °C, and 1,100 °C for 4 hours of melting time. The color of the 900 °C melt was a bright cobalt blue, the color of the 1,000 °C melt was a teal color, and the color of the 1,100 °C melt was an emerald green. Without being bound by theory, this change in color (i.e., transmittance) is due to the decrease in the Cu2+ / Cu1+ratio, which is governed by melting temperature. The colder the melt, the more copper remains in the 2+ oxidation state, which is favorable for this filter glass application, requiring high visible transmittance.

[0144] The glasses of the tables herein may be prepared using standard methods well- known to those skilled in the art. Such methods include a continuous melting process, such as would be performed in a continuous melting process, wherein the melter used in the continuous melting process is heated by gas, by electric power, or combinations thereof.

[0145] In addition, raw materials appropriate for producing exemplary glasses include commercially available sands as sources for SiCh; alumina, aluminum hydroxide, hydrated forms of alumina, and various aluminosilicates, nitrates and halides as sources for AI2O3; boric acid, anhydrous boric acid and boric oxide as sources for B2O3; periclase, dolomite (also a source of CaO), magnesia, magnesium carbonate, magnesium hydroxide, and various forms of magnesium silicates, aluminosilicates, nitrates and halides as sources for MgO; limestone, aragonite, dolomite (also a source of MgO), wolastonite, and various forms of calcium silicates, aluminosilicates, nitrates and halides as sources for CaO; and oxides,carbonates, nitrates and halides of strontium and barium. If a chemical fining agent is desired, tin can be added as SnCh, as a mixed oxide with another major glass component (e.g., CaSnCh), or in oxidizing conditions as SnO, tin oxalate, tin halide, or other compounds of tin known to those skilled in the art.

[0146] The glasses in the tables contain Sb20s as a fining agent, but other chemical fining agents could also be employed to obtain glass of sufficient quality. For example, exemplary glasses could employ any one or combinations of SnCh, AS2O3, CeCh, Fe20s, and halides as deliberate additions to facilitate fining, and any of these could be used in conjunction with the Sb20s chemical fining agent shown in the examples.

[0147] Tin oxide (e.g. SnCh) may be substituted oxides of antimony as a fining agent and as a means to keep the copper oxidized to maximize the Cu2+population in the glass, which is favorable for high visible transmittance and strong NIR absorbance. This would avoid the use of a regulated and environmentally undesirable specie.

[0148] Fe20s may be introduced to increase visible absorbance and improve durability in the range of 0.1 mol% to about 3 mol%. Titania may be used to increase Young’s modulus of the glass at concentrations of 0.25 mol% to about 5 mol%. SnCh-, Fe2C>3-, and TiCh-containing glasses were also made.

[0149] In addition to the elements deliberately incorporated into exemplary glasses, nearly all stable elements in the periodic table are present in glasses at some level, either through low levels of contamination in the raw materials, through high-temperature erosion of refractories and precious metals in the manufacturing process, or through deliberate introduction at low levels to fine tune the attributes of the final glass. For example, zirconium may be introduced as a contaminant via interaction with zirconium-rich refractories. As a further example, platinum and rhodium may be introduced via interactions with precious metals. As a further example, iron may be introduced as a tramp in raw materials, or deliberately added to enhance control of gaseous inclusions. As a further example, manganese may be introduced to control color or to enhance control of gaseous inclusions.

[0150] 2. Modifier identity, concentration, and ratio of 1+ to 2+ modifier cations

[0151] Specific modifier species and concentrations are required to achieve the weatherability performance. The modifier species include both the cationic species with +1 or +2 valence, i.e., being RO + R’20, where R’20 is at least one of I 2O, Na2O, and K2O, and RO is at least one of MgO, CaO, ZnO, SrO, and BaO. A modifier also influences the resultant optical properties of these glasses, as it can influence the redox ratio between Cu2+and Cu1+and shift the absorption peak positions of these two copper cations. The effect of the type, the concentration, and the ratio of the modifier on durability and optical properties are discussed together below.

[0152] Table 4 shows the compositions and weathering results of Examples 1-9 and illustrates the effect of the RO type on the weathering behavior. The weathering results were evaluated based on appearance of 1 mm thick polished discs of these compositions after exposure to 120 hours at 85 °C / 85% RH. These compositions have essentially identical concentrations of R2O including Li2O and K2O in these compositions. However, the RO content, including ZnO + SrO + BaO in these compositions, vary.

[0153] As shown in Table 4, the compositions that did not change in appearance after 120-hr exposure to 85 °C / 85% RH include Example 4, Example 5, Example 6, and Example 8. Example 4 includes ZnO as the only RO. Examples 5-6 include combinations of ZnO and SrO as RO. Example 8 includes a combination of ZnO, SrO, and BaO as RO. The examples including a combination of ZnO and BaO only as RO, i.e., Examples 1-3, 7, and 9 exhibited white spots or ‘patches’ and some were hazy.

[0154] Without being bound by theory, this difference in weathering performance is due to the difference in field strengths of these 2+ cations. Larger, more polarizable cations such as barium have lower energy bonds that result in the glass being more susceptible to corrosion relative to compositions that have higher field strength cations (e.g., Zn and Sr). However, there are also tradeoffs between durability and optical performance that must be considered when selecting the appropriate cation identity and concentration as described herein. As a trend, the higher the field strength of the cations, the more blue-shifted the cutoff wavelength is, which is the opposite of the targets. Higher field strength 2+ cations such as Mg and Ca do further enhance the weathering performance relative to Zn and Sr while having a deleterious effect on the optical properties, so they may not be used or may be used at a small percentage in the most preferable embodiments.

[0155] Table 4. Compositions and weathering results of Examples 1-9NC = No change; WS = White spots; WP =White patch; H= Haze

[0156] Table 5 shows the compositions and weathering results of Examples 10-18. These examples show that the addition of CaO may increase durability and simultaneously negatively impact the optical properties can be demonstrated. For example, Example 10, Example 13, Example 14, and Example 15 are nearly identical in composition except for their RO identities. Example 10 is a glass comprising ZnO and BaO. Examples 13-15 are the glasses comprising ZnO+BaO+CaO, wherein 15 mol% CaO was substituted for ZnO. As shown in Table 5, after 120 hours at 85 °C 85% RH, the Ca-free glass (Example 10) shows surface deposits due to corrosion, whereas the Ca-containing glasses Examples 13 and 14 showed no change. Example 15 was not tested but should also exhibit no change. These results show that higher field strength, less polarizable cations are beneficial for durability.

[0157] Table 5. Compositions and weathering results of Examples 10-18.NC = No change; D = deposits; WD = White deposit; LC= Light corrosion; CE= Corrosion on edges; NT=Not tested.

[0158] While the substitution of CaO as a part of the total RO package improves weatherability, it decreases the visible transmittance, as shown in FIG. 1. FIG. 1 compares the visible transmittance of “Ca-free” glass (Example 10) and Ca-containing glasses (Examples 13-15). The difference among Examples 13-15 is the fluorine concentration. Example 13 has 30 mol.% (5.33 wt.%) of fluorine. Example 14 has 15 mol% (2.70 wt. %) offluorine. Example 15 is fluorine-free. These spectra show that the addition of CaO decreases the visible transmittance, especially at shorter wavelengths (350-450 nm) and that decreasing fluorine concentration also decreases the visible transmittance for a fixed RO package. Example 10 has the same F concentration as Example 13, while Example 13 is less transparent and shows the impact of batching calcium.

[0159] Magnesium was expected to have an even more significant negative impact on optical properties. So, magnesium was not considered as a viable specie to include in these glasses, despite several Mg-containing compositions made.

[0160] The concentrations of total R’20 to total RO also influences durability. For example, Examples 3 and 7 as shown in Table 4 both contain ZnO and BaO but no SrO, and both exhibit corrosion when subjected to 85 °C / 85% RH. However, the composition with higher R^O and lower RO (Example 3) exhibits less corrosion than the glass with lower R’20 and higher RO. Example 3 comprises 10.17 mol% of total R2O and 31 mol% of total RO. Example 7 comprises 6.45 mol% of R^O and 36 mol% of RO. This suggests that a higher R2O concentration, for example, between 2 mol% and 18 mol. % (e.g., between 9 mol % and 13 mol%) may be favorable for durability.

[0161] There were also changes in the optical properties associated with this difference in R^O to RO concentrations. As shown in FIG. 2, the glass with the higher alkali (R2O) concentration (Example 3) has a higher visible transmittance in the UV and at short visible wavelengths than the composition with lower alkali concentration (Example 7). This suggests that the concentration of 1+ and 2+ modifier (R2O and RO) cations influence the ratio of ratio of Cu1+to Cu2+in the glass, where absorption losses in the UV and short visible wavelengths are attributed to the presence of Cu1+cation).

[0162] There are some exceptions that have been found with respect to durability and how it relates to the total R. 2O and RO concentration and identities (i.e., what ratio of species comprise them). As the inventors know, when about 5 mol% of SrO is substituted into in a glass where RO comprises ZnO+BaO (Examples 3 and 8), the weathering performance is increased such that the glass can withstand 120-hr at 85 °C / 85% RH without showing any surface corrosion. Additionally, it has been demonstrated that durability can be improved when increasing total R2O concentration from about 9 mol% to about 13 mol%.

[0163] However, it was found that even with the presence of the 5 mol% SrO in a glass comprising ZnO+BaO+SrO and a total R^O greater than 9 mol%, the weathering performance is impaired if the ZnO concentration falls below a threshold value. This is demonstrated by comparing Example 8 in Table 4 to Example 22 in Table 6.

[0164] Table 6 shows the compositions and the weathering results of Examples 19- 24.

[0165] Table 6. Compositions and weathering results of Examples 19-24.

[0166] Aside from a 1 mol% difference in CuO concentration, Examples 8 and 22 are almost identical with the exception of the total R’20 and ZnO concentrations. Example 8 has 6.44 mol% of R’20 and 26 mol% of ZnO, while Example has, 9.04 mol% of R^O and 22 mol% of ZnO. Based on the images taken after the weathering test, after 120-hr exposure to 85 °C / 85% RH, Example 8 was unaffected, but Example 22 showed surface corrosion. Based on these results, it was discovered that ZnO plays a significant role in durability and its concentration must exceed a certain threshold, for example, about 15 mol %, about 17% or about 22 mol%.

[0167] It is also noted that some compositions similar to Example 22 and having almost identical total R’20 and RO values, for example, Example 8 in Table 4, are resistant to corrosion after 120-hr in 85 °C / 85% RH. Example 22 has 37 mol% of RO and 9.04 mol% of R’20. Example 6 has 31 mol% of RO and 8.95 mol% of R^O. Example 8 has 36 mol% of RO and 6.45 mol% of R^O. This affirms that RO identity, i.e., what mixture of 2+ cations that are present, is critical to maintain good weathering performance.

[0168] In summary, to achieve both good weathering performance after 120-hr at 85 °C / 85% RH and achieve as red-shifted of a Cu2+absorbance as possible, parameters related to RO and R^O may be recommended. For example, the R^O concentration may be in a range of 2 mol% to 18 mol %, for example, a range of 4 mol% to 16 mol%, or in a range of 6 mol% to 14 mol%. Further about total R2O concentration may be made as described below related to the P2O5 concentration. The total RO concentration be in a range of 20 mol% to 40 mol%, for example, in a range of from 25 mol% to 40 mol%. The ZnO concentration may be higher than a threshold such as about 15 mol %, about 17% or about 22 mol%, while its upper limit may be about 40 mol%. The RO identity must be either ZnO-only, ZnO+SrO, and more preferably ZnO+SrO+BaO. BaO must be kept equal to or below 12 mol% and more preferably be lower than 10 mol%, and most preferably below 7 mol%. In some embodiments, ZnO is used in combination with SrO to ensure good durability, where SrO is at least 3 mol%, for example, at least 5 mol%.

[0169] 3. P2O5 concentration

[0170] The phosphorous concentration in this family of glasses was found to heavily influence the weatherability performance and optical properties. At A fixed concentration of CuO and AI2O3, increasing P2O5 concentration by a direct substitution for modifier cations (RO+R2O) redshifts the Cu2+absorbance further into the NIR, making it easier to achieve the T50% 635 nm cutoff wavelength, but simultaneously hinders durability. Examples of this behavior can be found by comparing several compositions in Table 7.

[0171] Table 7 shows the compositions (by mol%) and the weathering results of Examples 25-33.

[0172] Table 7. Compositions and weathering results of Examples 25-33.NC = No change; LH = Light haze; WH = White haze; WP= White patches

[0173] After exposed to 85 °C / 85% RH, glasses (1 mm thick disc) having the compositions of Examples 25-33 in Table 7 were examined for visual appearance and the images of the sample were taken. The results after exposure for 24 hours, 48 hours, and 120 hours are shown in Table 7. The weathering results of Examples 25-27 shows how profoundly the P2O5 concentration influences weathering. Example 25 has a P2O5 content (35 mol%) lower than that of Examples 26 and 27 (40 mol%). Significantly less corrosionwas observed than those with the higher P2O5 concentrations. This difference in weathering performance was also observed in the remaining low / high P2O5 compositions in Table 7, for example, Example 28 with a lower P2O5 concentration compared to the analogs having P2O5 concentrations, Examples 29 and 30, and Example 31 having lower P2O5 concentration compared to its analogs having a higher P2O5 concentration such as Examples 32 and 33.

[0174] While increasing P2O5 concentration has a deleterious effect on durability, it redshifts the cutoff wavelength to longer wavelengths for the compositions having a fixed CuO concentration. That is demonstrated by comparing the transmittance spectra of low P2O5 composition, Example 6, which contains 35 mol% P2O5 to the examples shown in Table 8.

[0175] Table 8 shows the compositions (by mol%) and the weathering results of Examples 34-42.

[0176] Table 8. Compositions and weathering results of Examples 34-42.WP = White patches; WS= Wet surface

[0177] Examples 34-42 in Table 8 have 50 mol% of P2O5. In the present disclosure, a high P2O5 content refers to glasses having >40 mol % P2O5.

[0178] The difference in optical properties, specifically the cutoff wavelengths, between a durable low P2O5 composition (e.g., Example 6 with 35 mol% of P2O5) and a high P2Os-containing composition (e.g., Example 35 with 50 mol% of P2O5.) is shown in FIG. 3. As observed, the high P2Os-containing composition (Example 35) exhibits a T50% cutoff wavelength of 614 nm, whereas the low P2O5 glass (Example 6) exhibits a cutoff of 598 nm, approximately 16 nm blue-shifted. However, like the compositions in Table 7 with higher P2O5 concentrations (Examples 26, 27, 29, 30, 32, and 33 with 40 mol% P2O5), and Examples in Table 6 with an even higher P2O5 concentrations (50 mol%), they perform poorly in 85 °C / 85% RH (Tables 7 and 8). It was also found that the compositions with even higher P2O5 concentrations had cutoff wavelengths that are further redshifted but had even worse durability performance. This is despite the fact that the lower P2O5 containing glass (Example) has 3 mol% less copper, which would by default redshift the cutoff, thus further demonstrating the significant impact phosphorous concentration has on the optical properties, specifically the peak position of the Cu2+absorbance.

[0179] Compositions with P2O5 concentrations as low as 33 mol% were successfully melted and produced stable glasses. Table 9 shows the compositions (by mol%) and the optical performance results of Examples 43-51.

[0180] Table 9. Compositions and optical performance results of Examples 43-51.

[0181] FIG. 4 shows the transmittance spectra of 0.2 mm thick polished parts of Examples 44-51. The maximum transmittance and corresponding wavelength as well as the cutoff wavelength shown in Table 9 were calculated from spectra.

[0182] While low P2O5 compositions produced stable glasses, they generally exhibited low visible transmittance and blue-shifted cutoff wavelengths, which are undesirable attributes in the context of what the targeted optical performance. For example,Example 48 with a batched concentration of P2O5 of 33 mol% has a cutoff wavelength of 589.9 nm.

[0183] The optical performance data of Examples 44-51 shown in Table 9 and FIG. 4 also suggest that a total R2O concentration higher than a certain percentage, for example, >10 mol%, is less preferred as it promotes lower visible transmittance and strongly blue-shifted cutoff wavelengths. These results also show that again R2O identity influences the cutoff wavelength.

[0184] In summary to achieve good weatherability performance after 120 hours at 85 °C / 85% RH, the P2O5 concentration needs to be minimized to be in a range, for example, below 40 mol% but above 30 mol%, and most preferably between 32 and 37 mol%. However, to redshift the cutoff wavelength, maximizing the P2O5 concentration is favorable if the durability requirement can be relaxed.

[0185] 4. Fluorine concentration

[0186] Fluorine may be in a suitable range, for example, in the range of 1 mol% to 60 mol% such as from 20 mol% to 60 mol%, from 20 mol% to 50 mol%, or from 30 mol % to 50 mol mol%. Fluorine may have less impact on durability; however, fluorine may act as an oxidizing agent that decreases the amount of Cu1+present in the glasses provided in the present disclosure. This is demonstrated in the transmittance spectra of Examples 13-15 in FIG. 1. Examples 13-15 are almost identical except for their fluorine concentration.Examples 13, 14, and 15 have a fluorine content of 30 mol%, 15 mol%, and 0 mol%, respectively. As observed, the fluorine-free composition (Example 15) has the lowest transmittance and as the fluorine content is increased, so does the transmittance of Example 14 and Example 13. This increase in transmittance is attributed to the decrease in Cu1+and the subsequent conversion of it to the higher 2+ oxidation state.

[0187] One additional benefit of fluorine is the decrease in melting temperature, which has been found to decrease the amount of Cu1+that is formed during melting and inturn enables an increase in visible transmittance. It is therefore believed that having at least 20 mol% of fluorine in the composition is preferable. More preferably, the fluorine content is in a range of from 30 mol% to 50 mol%. Fluorine is most preferable to ensure that the copper is fully oxidized due to its strong oxidizing effect and the decrease in melting temperature.

[0188] One risk to consider when batching fluorine is if the glass is over-melted and fluorine is lost by volatilization either by melting too hot or too long, it can act as a reducing agent and in-turn decrease the Cu2+population and promote the formation of the 1+ oxidationstate that can decrease visible transmittance. Accordingly, when high concentrations of fluorine are batched, care must be taken to maximize the retention by tailoring the melting profile accordingly, and / or melting in sealed systems with controlled atmospheres, and or cold crown melters.

[0189] 5. Use of Antimony

[0190] While oxides of antimony such as Sb20s and Sb20s are not environmentally favorable species, it has been demonstrated that they have a positive impact on the peak visible transmittance of these blue copper filter glasses, presumably by promoting the more complete oxidation of the copper in the glass to the 2+ state. Examples of this effect can be observed from compositions in Table 10.

[0191] Table 10 shows the compositions (by mol%) of Examples 52-60. Table 10 also shows the optical performance results of Examples 52-53.

[0192] Table 10. Compositions and some optical performance results of Examples52-60.

[0193] Based on the appearance of as-annealed Examples 52 and 53, the “high” antimony (Sl^Ch) glass (Example 52) is bluer in color and more transparent than its “low” antimony analog (Example 53). FIG. 5 shows the transmittance spectra of 0.21 mm thick polished glass samples of Examples 52 and 53. As shown by the transmittance spectra, the high antimony composition, Example 52, exhibits higher transmittance in the UV and shorter visible wavelengths. Table 10 also lists the maximum visible transmittance and wavelength, the NIR cutoff wavelength, and transmittance at 1,200 nm for the spectra of Examples 52 and 53. The values show that the high antimony composition (Example 52) has an almost identical cutoff wavelength and percent transmittance at 1,200 nm to its low antimony analog (Example 53), but exhibits higher visible transmittance. This is attributed to its lower Cu1+population, which attenuates UV and shorter visible wavelengths.

[0194] It is known that oxides of antimony can also increase the chemical durability and weatherability of some phosphate glasses. However, no measurable difference in weathering was observed across the concentrations of antimony investigated in these glasses.

[0195] In summary, it is preferred to have at least 0.3 mol% Sb20s in the glass and in some embodiments may be beneficial to have up to 3 mol% Sb20s or its oxidized form Sb2O5.

[0196] 6. Lithium Concentration

[0197] It was generally reported in the literature that higher field strength cations such as lithium ion tends to blueshift the Cu2+absorbance and reduces the visible transmittance at longer wavelengths; however, such cations are also known to improve durability. In the present disclosure, it was found that the additions of Li improved chemical durability. Further, lithium lowers the T200P (i.e., peak melting temperature), which enables ‘more’ or ‘the majority’ of the copper to be kept in the 2+ oxidation state, which is favorable for this filter glass application, specifically to maximize visible transmittance at short visible wavelengths.

[0198] Compositions with up to 20 mol% Li2O have been melted and stable glass was produced at this high Li2O concentration such as Example 43 (Table 9). The trend in optical transmittance and cutoff wavelength as a function of Li2O concentration can be observed by comparing compositions of the Examples in Table 11.

[0199] Table 11 shows the compositions (by mol%) of Examples 61-69. Table 10 also shows the optical performance results of Examples 61-63.

[0200] Table 11. Compositions and some optical performance results of Examples 61-69.

[0201] Examples 61-63 as shown in Table 11 comprise 0, 4 mol%, and 8 mol% of Li2O, respectively, where Li was substituted for K. FIG. 6 shows the transmittance spectra of parts 0.21 mm thick polished glass samples of Examples of 61-63. As shown in FIG. 6, as Li2O is increased from 0 to 8 mol%, the peak transmittance increases (slightly) and cutoff wavelength redshifts by about 5 nm. This is contrary to the literature that suggests high fieldstrength cations blue shift the cutoff wavelength. This is a beneficial finding because Li can also improve chemical durability.

[0202] Based on these observations and the best embodiments of these glasses, Li2O concentration can be in a range of from 1 mol% to 20 mol%, preferably from 2 mol% to 15 mol%, more preferably in a range of from 3 mol% to 10 mol% such as between 4-7 mol%. Higher Li2O concentrations, for example, more than 10 mol%, may be beneficial to increase weatherability but may drive up batch cost and increase the risk of devitrification.

[0203] 7. Addition of Rare Earth Elements and Nb2Os

[0204] The addition of rare earth (RE) elements can increase the Young’s modulus of glasses and may also improve chemical durability.

[0205] Table 12 shows the compositions (by mol%) of Examples 70-78.

[0206] Table 12. Compositions of Examples 70-78.

[0207] As shown in Table 12, compositions with Y2O3 and La20s have been prepared. These samples include Examples 72, 73, and 76-78. Out of these compositions, only the glass with 1 mol% Y2O3 produced a stable glass, which may have increased Young’s modulus. All others opalized when pouring from the melt. Appearance of as-annealed optical patties of glasses Examples 70-78 was evaluated. Only Examples 72, 74, and 75 provided stable glasses. Examples 74 and 75 had bt^Os, which diminished the visible transmittance to a value below which would be useful for this filter glass application.

[0208] In summary, based on the limited information collected, if a rare earth element is introduced to these compositions, it is preferable to use Y2O3 at concentrations below 1.6 mol%.

[0209] 8. Preferred and Additional Examples

[0210] Among the compositions described above, the preferred examples exhibiting high visible transmittance, a redshifted cutoff wavelength, and good near-infrared absorption include Examples 52-60. Additional preferred examples are Examples 79-87 and Examples 88-92 as shown in Tables 13 and 14.

[0211] Table 13 shows as-batched compositions of Examples 79-87 in mol%.

[0212] Table 13. Compositions and properties of Examples 79-87NC=No change; FH=Faint haze; LH = Light haze

[0213] Table 14 shows as-batched compositions of Examples 88-93 in mol%.

[0214] Table 14. Compositions and properties of Examples 88-93.NC=No change; FH=Faint haze

[0215] Examples 81 and 87 in Table 13 were tested for optical performance and durability. As two of the preferred examples, they have high visible transmittance, some NIR attenuation, show minimal change in surface quality after 120 hours at 85 °C / 85% RH and exhibit <2% change in transmittance across the targeted 300-1200 nm wavelength range after being exposed to 120-hr 85 °C / 85% RH (Table 13).

[0216] FIGS. 7-8 shows the transmittance of Example 81 and Example 87, respectively, at a thickness of 0.21 mm before and after 120-hr exposure to 85 °C / 85% RH. Table 13 also lists some key optical attributes from the spectra, including the maximum transmittance wavelength and value, 50% cutoff wavelength, and the transmittance at 1200 nm before and after the exposure. FIGS. 9 and 10 show the percent change in transmittance measured before and after weathering for Example 81 and Example 87, respectively. Example 81 showed less than 0.4% change in the wavelength range of 300 nm to 1,200 nm and less than 0.2% change in the NIR range. Example 87 showed less than 2% change in the wavelength range of 300 nm to 1,200 nm and less than 0.2% change in the NIR range.

[0217] FIG. 11 shows the transmittance spectra of 0.21 mm thick polished samples of Example 88-93 in Table 14. Table 14 lists some key optical attributes obtained from the spectra, including the maximum transmittance wavelength and value, 50% cutoff wavelength, and the transmittance at 1200 nm. The compositions in Table 14 except Example 93 with higher P2O5 showed no change in surface quality after 120-hr at 85 °C / 85% RH. As shown in Table 14 and FIG. 11, Examples 88-92 showed excellent performance.

[0218] The compositions have been listed by the mole percentages of both oxide and fluoride species. Any combination of oxides and fluorides yielding the final target fluorine concentration would fall within the scope and that all these compositions are subject to a variety of different raw batch materials.

[0219] Example 87 in Table 13 as a working example is further illustrated based on the raw materials and resulting composition, as shown in Table 15. In the Examples described herein, the fluorine sources used include AIF3, CaF2, SrF2, BaF2, ZnF2, or a combination thereof. In this example, SrF2, BaF2, and ZnF2 were used. The total fluorine content is the sum of the fluorine from all the fluoride species. The amount of one or more fluorides used are presented for the convenience of description. These fluorides also provide the corresponding oxides.

[0220] The fluorine may be combined with Al, Ca, Sr, Ba, Cu, Zn, Li, Na, and K. For the metals such as Al, Ca, Sr, Ba, and Zn in the fluorine source(s) used, the total amount of a corresponding oxide equivalent should include the amount of the metal fluoride used. For example, total amount of equivalents of oxides (or oxide equivalents) such as SrO, BaO, or ZnO should include the total amount of the corresponding oxides and fluorides. The content of zinc oxide equivalent should be 18.7 mol%. The SrO equivalent and the BaO equivalent are 10 mol% and 5 mol%, respectively. The amounts of the oxides of Al, Li, Na, K and Cu listed in Table 15 are considered as the mole percentage of the corresponding oxideequivalents. The oxides of Al, Ca, Sr, Ba, Cu, Zn, Li, Na, and K may be partially replaced or combined withtheir fluoride equivalents (e.g. BaO for BaF2).

[0221] Therefore, the amount of “total R,” where R= Mg, Ca, Sr, Ba and Zn, is a combined amount (mol%) of oxide and fluoride listed in the composition tables. The amount “total R” is also the same as “total RO,” which is the total amount of oxide equivalents. The amount of “total R’20,” where R’ is Li, Na, and K, is the total amount of corresponding oxide equivalents.

[0222] Table 15. Raw Materials and Composition of Example 87 as One Example of the Compositions

[0223] 8. Removal of Antimony and Addition to Method of Making

[0224] Sb2O3can be also removed from the compositions, and the optical properties can be tuned depending on oxidation state of the compositions.

[0225] In some applications, a limit of Sb2O3 is required to be lower than 1,000 ppm or 700 ppm. As described above, antimony is needed to oxidize glass and lower the fraction of Cu+. The reduction of Cu+aids for the higher transmittance in the UV and shorter visible wavelengths. To account for the reduced antimony, oxygen bubbling was applied during glass melting.

[0226] Table 16 lists the compositions of Examples 94 and 95, which are based Example 87 but with decreasing levels of Sb2O3, melted in induction furnace, which iscapable for atmosphere control. The batch powder was soaked with O2 at 0.5 slpm (with bubbler tube inserted in batch) for one hour, then melted at 900 °C for 3 hours.

[0227] Table 16. Compositions of Examples 94 and 95

[0228] The optical data are shown in FIG. 12. Table 17 compares the results of Examples 94 and 95 to the data of Example 87. “T1200” refers to the transmittance at 1,200 nm. “Lambda Tmax” refers to the wavelength for the maximum transmittance. “Tmax” refers to the maximum transmittance. “NIR T50” refers to the NIR cutoff wavelength having 50% transmittance. The results suggest that by introducing O2, antimony can be reduced to the at least < 1,000 ppm level while achieving the desired optical properties, comparable to the high-Sb (8,000 ppm) containing composition. When completely removing Sb from composition, there is a slight decrease (~ 0.8%) in the transmittance in the visible light range.

[0229] Table 17. Optical properties of Examples 94 and 95 Compared to Example 87

[0230] Several double-melt glasses based on the composition of Example 94 were also made to optimize the oxidizing effect. In the first step, experiments were conducted to remove Sb20s, or Sb20s and Cu3(POs)2, or Sb20s together with Cu3(POs)2 and the fluorides from a batch of Example 94. Other remaining ingredients were melted in ambient condition. The removed ingredients were added back in the second step and mixed with the cullet made in the first step. The mixture was melted under O2 bubbling.

[0231] FIG. 13 shows the transmission spectra for melts made with single and two- step meltingprocess targeting on composition of Example 94, wherein different components were separated from the 1ststep batch and added in the 2ndstep with O2 bubbling. Table 18 summarizes the results from the samples made. It was observed that the double melt process improves melt quality with less speckles and adding Sb2O3 separately in the 2ndstep promotes a slight better transmittance in low wavelength as compared to single melt. The double melts have the same final composition with the single melt, which is the example of 94. All have the same Sb2C>3 level of 0.04 mol.%.

[0232] Table 18. Optical performance results of the double melt samples compared to the single melt counterpart.

[0233] It was also found that increased amounts of Li2O and CaO also improve the meltability and durability as well as improved optical properties. Table 19 shows the compositions of Examples 96-99. FIG. 14 shows the transmission spectra for Examples 96-99 compared to Example 87. Table 20 shows the optical performance data of Examples 96-99 compared to Example 87.

[0234] Table 19. Compositions of Examples 96-101

[0235] Table 20. Optical performance data of Examples 96-99 compared to Example 87.

[0236] Table 21 shows the compositions of Examples 102-104. FIG. 15 shows their transmission spectra with comparison to Example 87. Table 22 shows the optical performance data of Examples 102-104 compared to Example 87.

[0237] Table 21. Compositions of Examples 102-104.

[0238] Table 22. Optical performance data of Examples 102-104 compared toExample 87

[0239] The compositions can be also characterized by weight percent. For example, in the Examples, AI2O3 was generally in a range of from 3-5 wt.%, P2O5 was generally in a range of 40-60 wt.%, and CuO was generally in a range of 3-13 wt.%. To the purpose of conciseness, the compositions in weight percent are not shown herein.

[0240] In addition to the above components, the glass compositions described herein can include various other oxides to adjust various physical, melting, fining, and forming attributes of the glasses. Examples of such other oxides include, but are not limited to, TiCE, ZrCE, HfCE, Nb2Os, Ta2Os, MoOs, WO3, ImC , Ga2C , Bi2C , GeCE, PbO, SeC , TeCE, Y2O3, La2C , Gd2C , and others known to those skilled in the art. In some embodiments, these oxides are not added. In some embodiments, the amount of each of these oxides can be less than or equal to 0.5 mole percent such as less than 0.1 mole percent including zero percent, and their total combined concentration can be less than or equal to 2.0 mole percent such as less than 1.0 mole percent. In some embodiments, the total combination concentration of these oxides is in a tamp amount, for example, less than 0.1 mole percent.

[0241] The glass compositions described herein can also include various contaminants associated with batch materials and / or introduced into the glass by the melting, fining, and / or forming equipment used to produce the glass, particularly Fe2C and ZrCE. The glasses can also contain SnCE either as a result of Joule melting using tin-oxide electrodes and / or through the batching of tin containing materials, e.g., SnCE, SnO, SnCCE, and SnCECE. In some embodiments, the glass is substantially free or free of Fe2C , TiCE, and ZrCE

[0242] Hydrogen is inevitably present in the form of the hydroxyl anion, OH', and its presence can be ascertained via standard infrared spectroscopy techniques. Dissolvedhydroxyl ions significantly and nonlinearly impact the annealing point of exemplary glasses, and thus to obtain the desired annealing point it may be necessary to adjust the concentrations of major oxide components so as to compensate. Hydroxyl ion concentration can be controlled to some extent through choice of raw materials or choice of melting system. For example, boric acid is a major source of hydroxyls, and replacing boric acid with boric oxide can be a useful means to control hydroxyl concentration in the final glass. The same reasoning applies to other potential raw materials comprising hydroxyl ions, hydrates, or compounds comprising physisorbed or chemisorbed water molecules. If burners are used in the melting process, then hydroxyl ions can also be introduced through the combustion products from combustion of natural gas and related hydrocarbons, and thus it may be desirable to shift the energy used in melting from burners to electrodes to compensate. Alternatively, one might instead employ an iterative process of adjusting major oxide components so as to compensate for the deleterious impact of dissolved hydroxyl ions.

[0243] In addition to the major oxide components of exemplary glasses, and the minor or tramp constituents noted above, halides may be present at various levels, either as contaminants introduced through the choice of raw materials, or as deliberate components used to eliminate gaseous inclusions in the glass. As a fining agent, halides may be incorporated at a level of about 0.4 mol% or less, though it is generally desirable to use lower amounts if possible, to avoid corrosion of off-gas handling equipment. In some embodiments, the concentrations of individual halide elements are below about 200 ppm by weight for each individual halide, or below about 800 ppm by weight for the sum of all halide elements. As described above, the glass compositions are substantially free of chlorine.

[0244] The glass and the compositions provided in the present disclosure have significant advantages. For example, the glass compositions exhibit desirable physical properties, optical performance, and durability. The glass compositions are suitable for use as NIR filer.

[0245] In another aspect, the present disclosure provides an article comprising the glass or the glass composition described herein. For example, a filer comprises the glass or the glass composition described here.

[0246] As described above, the present disclosure provides novel near-infrared absorbing filter glass compositions with a red-shifted cutoff wavelength and superior weatherability. These glasses are designed to operate at short path lengths (~200 pm). The glasses, alone or in combination with a coating, can be used as a blue glass filter. The blue glass filters have a market greater than several hundred million dollars per year. Theestimated market for the blue filter glass without coating is at least $50 million. Therefore, the products provided in the present disclosure have a significant potential in the blue glass filter market.

[0247] In another aspect, the present disclosure provides a device comprising the glass or glass composition as described herein.

[0248] In another aspect, a method for producing the glass or the glass composition as described herein is provided. Such a method comprises at least one step of mixing and melting raw materials in mole percent on an oxide basis so as to provide the oxides as described. Such a method may further comprise making a sheet comprising the glass composition.

[0249] Although the subject matter has been described in terms of exemplary embodiments, it is not limited thereto. Rather, the appended claims should be construed broadly, to include other variants and embodiments, which may be made by those skilled in the art.

Claims

What is claimed is:

1. A glass comprising in mole percent on an oxide basis and by a fluorine content:P2O5: 30-40;SiO2: 0-10;K2O: 0-15;ZnO: 15-40;CaO: 0-12;SrO: 0-20;MgO: 0-10;BaO: 0-12;CuO: 4-18;AI2O3: 1-7;Li2O: 1-20;Na2O: 0-10;Sb2O3: 0-5; and total fluorine (F): 1-60; wherein a combined concentration of RO is in a range from 20 to 40, a combined concentration of R’2O is in a range of from 2 to 18,RO is selected from the group consisting of MgO, CaO, SrO, BaO, and ZnO, and R’2O is selected from the group consisting of Li2O, Na2O, and K2O.

2. The glass of claim 1, wherein one or more of AI2O3, CuO, MgO, CaO, SrO, BaO, ZnO, Li2O, Na2O, and K2O are partially fluorinated.

3. The glass of claim 1, wherein the total fluorine is in a range of from 20 to 60 by mole percent.

4. The glass of claim 1, wherein the total fluorine is in a range of from 30 to 50 by mole percent.

5. The glass of claim 1, wherein P2O5 is in a range of from 31 to 38 by mole percent.

6. The glass of claim 1, wherein P2O5 is in a range of from 32 to 37 by mole percent.

7. The glass of claim 1, wherein CuO is in a range of from 5 to 17 by mole percent.

8. The glass of claim 1, wherein CuO is in a range of from 6 to 10 by mole percent.

9. The glass of claim 1, wherein the combined concentration of RO is in a range of from 22 to 38 by mole percent.

10. The glass of claim 1, wherein the combined concentration of RO is in a range of from 26 to 35 by mole percent.

11. The glass of claim 1, wherein RO is selected from ZnO only, a combination of ZnO and SrO, and a combination of ZnO, SrO and BaO.

12. The glass of claim 1, wherein ZnO is in a range of from 16 to 35 by mole percent.

13. The glass of claim 1, wherein ZnO is in a range of from 17 to 30 by mole percent.

14. The glass of claim 1, wherein the combined concentration of R’20 is in a range of from 4 to 16 by mole percent.

15. The glass of claim 1, wherein the combined concentration of R^O is in a range of from 6 to 14 by mole percent.

16. The glass of claim 1, wherein R^O is selected from I 2O and K2O and is substantially free of Na2O.

17. The glass of claim 1, wherein I 2O is in a range of from 3 to 10 by mole percent.

18. The glass of claim 1, comprising in mole percent on the oxide basis and by the fluorine content:P2O5: 31-38;SiO2: 0-8;K2O: 4-12;ZnO: 16-35;CaO: 1-4;SrO: 3-18;MgO: 0-4;BaO: 0-10;CuO: 5-17;AI2O3: 2-6;Li2O: 2-15;Na2O: 0-5;Sb2O3: 0-4; and total fluorine (F): 20-60; wherein the combined concentration of RO is in a range from 22 to 38, the combined concentration of R’2O is in a range of from 4 to 16.

19. The glass of claim 1, comprising in mole percent on the oxide basis and by the fluorine content:P2O5: 32-37;SiO2: 0-6;K2O: 5-12;ZnO: 17-30;CaO: 2-3;SrO: 5-12;MgO: 0-2;BaO: 0-7;CuO: 6-10;A12O3: 3-6;Li2O: 3-10;Na2O: 0-2.5;Sb2O3: 0-3; and total fluorine (F): 30-50; wherein the combined concentration of RO is in a range from 26 to 35, the combined concentration of R’2O is in a range of from 6 to 14.

20. The glass of claim 1, wherein the glass is substantially free of Sb20s, or the glass further comprises SnCh.

21. The glass of claim 1, further comprising Y2O3 at concentrations from 0 to 1.6 mol%.

22. The glass of claim 1, wherein the glass has a red-shifted cutoff wavelength having at least 50% transmittance at a thickness of 0.21 mm is at least 635 nm or longer.

23. The glass of claim 22, wherein at a thickness of 0.21 mm, the glass has a transmittance higher than 85% at wavelengths in a range of 425-465 nm, a transmittance higher than 87% at wavelengths in a range of 466-560 nm, a transmittance lower than 5% at wavelengths in a range of 750-800 nm, and a transmittance lower than 10 % at a wavelength of 1,200 nm.

24. The glass of claim 23, wherein a change in the transmittances is lower than 1% after the glass is exposed to 85 °C / 85% relative humidity (RH) for 120 hours.

25. An article comprising the glass of claim 1.

26. The article of claim 25, wherein the article is an optical filter for filtering near infrared light.

27. A method for producing the glass of claim 1, comprising mixing and melting raw materials in mole percent on the oxide basis and by the fluorine content.

28. The method of claim 27, wherein a raw material for the total fluorine is selected from the group consisting of AIF3, CaF2, SrF2, BaF2, ZnF2, or any combination thereof.

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