High refractive index low density glass

Abstract

The invention relates to optical glass with the refractive index larger than 1.85, a glass product containing the optical glass and application of the optical glass, in particular to application in the fields of optical devices, lenses, super-structure optical elements and augmented reality (AR).

Description

TECHNICAL FIELD

[0001] The present invention relates to an optical glass having a refractive index greater than 1.85, glass articles comprising the optical glass and uses thereof, in particular in the field of optical devices and lenses, super-structured optical elements and Augmented Reality (AR). BACKGROUND

[0002] The present invention relates to eyeglasses that can be used in the field of Augmented Reality (AR). For AR eyeglasses, glasses of high refraction, i.e. glasses having a high refractive index, are advantageous in that they enable an enhanced Field of View (FoV). On the other hand, the density of such glasses generally increases disproportionately with increasing refractive index. This means that even if the wafer thicknesses applied in AR can be thinner, the lenses will still be significantly heavier, resulting in discomfort when wearing AR eyeglasses for a long time. With the trend gradually shifting from head-mounted devices to the form of standard eyeglasses, which are worn for a long time or always like ordinary eyeglasses, it is necessary to reduce the weight of the eyeglasses. Such weight reduction is also advantageous in many other application fields, for example in the field of Digital Single Lens Reflex (DSLR) cameras, where the camera lenses are usually very bulky and heavy, which also significantly increases the battery power consumption required for autofocus.

[0003] Some glasses in the prior art are derived from a niobium phosphate or titanium phosphate system, i.e. they contain a large amount of P2O5 and niobium or titanium. These glasses have certain problems in production, for example, due to the high melting and fining temperatures in the phosphate system with reducing action, which leads to oxygen loss and thus to a lower oxidation state. For example, for niobium, this oxidation state is lower than V, and for titanium, it is lower than IV. This can lead to a brown to black coloration in the niobium system or a blue, yellow-green to brown, even black coloration in the titanium system. In addition, titanium significantly increases the tendency to crystallize, which is a well-known problem in the field of heavy flint glasses with high refractive index, for example, such glasses cannot be subjected to secondary hot press forming. Unlike niobium, even the highest oxidation state of titanium produces an absorption at the edge of the visible range, which, when the titanium concentration is high, leads to the well-known yellowing of barium titanate silicates.

[0004] In addition, as with the family of high refractive index heavy flint glasses or lanthanide heavy flint glasses, the family of niobium phosphate glasses not only tends to interfacial crystallization, but also exhibits extremely fast crystal growth, which makes glasses that can have preformed nuclei face serious challenges in subsequent cooling (stress cooling or refractive index adjustment). In addition, the glass itself is known to be relatively brittle, so it is difficult to polish it into very thin wafers.

[0005] On the other hand, at least for niobium phosphate glass, despite containing P2O5, its weather resistance is relatively good. This high-refractive-index glass has a low density, which improves wearing comfort. These glass families have been documented in the literature.

[0006] While the refractive index range of commercially available lanthanide heavy flint glass systems (Lanthanschwerflint-Systeme) is suitable for AR applications, its refractive index n... d The combination of density and other factors is clearly undesirable. In particular, the high lanthanum oxide content results in a relatively high density and Abbe number for this type of glass. Furthermore, the relatively high hardness of this type of glass necessitates longer grinding times, leading to increased wafer manufacturing costs. In some cases, the cost of raw material glass is also significantly higher due to the use of rare earth elements, tungsten oxide, tantalum oxide, and other expensive raw materials in their production. In the field of heavy flint glass, Nb₂O₅ is often the cost driver (Gemengekostentreiber), while other raw materials, even those of optical grade, are relatively inexpensive in comparison. Moreover, most existing lanthanide heavy flint glasses do not contain alkaline oxides, thus preventing chemical tempering. However, depending on the application, chemical tempering can be more beneficial in improving the mechanical stability of potentially increasingly thinner optical components (such as eyeglass lenses) used in AR applications.

[0007] In this region of the Abbott scale, many heavy flint glasses (such as P-SF glass) are problematic, partly due to their cost of raw materials (Gemengekosten) and partly due to their high Bi₂O₃ content. They are very soft (i.e., easily scratched) and have unfavorable UV transmission edges, such as insufficiently steep UV edges and / or UV edges shifted towards longer wavelengths in the spectrum. In particular, P-SF glass is manufactured discontinuously in a platinum crucible, which can lead to problems with the platinum alloys and the reduction of Bi(III) to Bi(O) in the furnace.

[0008] As mentioned above, there are some glasses that are more or less suitable, but most of them still have too low a refractive index (typical heavy flint glass) or are difficult to process or handle (typical lanthanide heavy flint glass).

[0009] In addition, lead-free heavy flint glass is known in the prior art, which contains a relatively high amount of Nb2O5. Nb2O5 contributes significantly to the high refractive index of these glasses, but its density is relatively high, resulting in high raw material costs. Summary of the Invention

[0010] The purpose of this invention is to provide a high refractive index n dThe glass should be of the lowest possible density. It should have the highest possible net transmittance, be easily thermoformable, and be easily machinable. To achieve this, the hardness should not be too low (otherwise, there will be too many scratches and microcracks) nor too high (otherwise, excessive grinding time will also produce microcracks). The glass should also have high chemical resistance and be economical to manufacture.

[0011] On the one hand, the solution of the present invention to achieve the above-mentioned objective is an optical glass with a refractive index n d Greater than 1.85, Abbe number v d Less than 35, temperature T max It is not higher than 1350°C and contains at least SiO2 and TiO2, and contains less than 30.0 mol% of SiO2, less than 2.0 mol% of Nb2O5, less than 17 mol% of BaO and less than 5.0 mol% of Ln2O3, wherein Ln2O3 = Y2O3, La2O3, Gd2O3 and / or Yb2O3.

[0012] Within the scope of this invention, a glass system containing TiO2 and SiO2 has been discovered that, compared to the aforementioned glasses composed of niobium phosphate or titanium phosphate systems, achieves greater stability in internal transmission and a higher refractive index, but has a relatively lower density. Furthermore, compared to the aforementioned niobium phosphate glasses, this glass system has higher hardness and lower material costs.

[0013] The refractive index n of the optical glass according to the present invention d It is greater than 1.85 and preferably not greater than 2.05.

[0014] In an advantageous embodiment, the refractive index n d The value is at least 1.87, preferably at least 1.88, preferably at least 1.89, preferably at least 1.90, preferably greater than 1.90, preferably at least 1.92 or at least 1.93, preferably at least 1.95, preferably at least 1.960, preferably at least 1.965, preferably at least 1.970, preferably at least 1.975, preferably at least 1.980, preferably at least 1.985. Advantageous n d The upper limit can be 2.05 or 2.050 or 2.045 or 2.040 or 2.035 or 2.030 or 2.025 or 2.020. Generally, the refractive index is thus advantageously in the range of greater than 1.85 to 2.05. Those skilled in the art know the refractive index n. d This specifically refers to the refractive index at a wavelength of approximately 587.6 nm (the wavelength of the helium d line). Those skilled in the art know how to determine the refractive index n. d .

[0015] The refractive index is preferably determined using a refractometer, particularly a V-block refractometer. Specifically, a sample with a square or nearly square base (e.g., approximately 20 mm × 20 mm × 5 mm) can be used. When using a V-block refractometer, the sample is typically placed within a V-block prism with a known refractive index. The refraction of the incident beam depends on the difference between the sample's refractive index and the V-block prism's refractive index, thus allowing the determination of the sample's refractive index. The measurement is preferably performed at 22°C.

[0016] According to the present invention, the Abbe number of the glass, i.e., the dispersion coefficient (ν), is... d The dispersion coefficient is less than 35. In advantageous embodiments, the dispersion coefficient is less than 32, preferably less than 30 or less than 25, more preferably less than 24 or less than 23 or less than 22 and / or greater than 18, more preferably greater than 18.5, and even more preferably greater than 19.0. The dispersion coefficient ν is calculated in a known manner. d The refractive index n was determined using a refractometer. d (approximately 587.6 nm), n F (approximately 486nm) and n C (Approximately 656nm), and related to each other according to the following formula: v d = (n d -1) / (n F -n C ).

[0017] Furthermore, according to the invention, the temperature T of the glass max ≤1350°C. T max Melting and refining temperatures are composition-related glass parameters that represent the minimum temperature required to produce a "refined" melt from the starting material (e.g., raw material, cullet, etc.) during the melting process. A "refined" melt exists when it contains no melt residue (e.g., incompletely melted raw material) and no crystals. As mentioned above, melting and refining temperatures should be as low as possible to prevent refractory materials from entering the glass and to prevent discoloration of the glass by polyvalent ions in low oxidation states. This improves net transmittance. Because the highest possible net transmittance is required, melting and refining temperatures cannot be arbitrarily set high; therefore, the melting temperature is limited at an upper limit, which is why the temperature point described in this article is also called "T". max The reason for this is T. max This refers to the lowest temperature at which a clear, amorphous melt can be produced. Based on this relationship, T... max It is a good indicator for measuring the liquidus temperature of glass (see below).

[0018] Within the scope of this invention, the Tg of the glass composition is systematically determined by conducting a series of tests on a laboratory scale.max The process involves melting identical 20 ml glasses from the starting components in small crucibles at different maximum temperatures, with a temperature gradient of 10°C. The temperature is gradually increased from the lowest to the highest temperature, and the melting results are then visually evaluated to determine whether a clear melt has formed or whether there are any residues and / or crystals remaining in the glass.

[0019] The T of the composition is determined in this way. max The value can also be reproduced in a larger volume (e.g., 1 liter) of laboratory melt. Furthermore, further experiments have shown that the temperature point T... max It is only slightly above the glass liquidus temperature. It can be inferred that temperature point T... max It can be determined using this simple and easy laboratory method, and is a good indicator for measuring the glass liquidus temperature, without the need for precise measurement. In an advantageous improvement of the invention, T... max The temperature is not higher than 1330°C, advantageously not higher than 1320°C, preferably not higher than 1310°C, and more preferably not higher than 1300°C. In some advantageous variations, T... max Not higher than 1290°C or not higher than 1280°C.

[0020] In an advantageous embodiment, the glass transition temperature T of the glass is... g The temperature is between 500°C and 800°C. Preferably, T g The temperature can be above 540°C, advantageously above 560°C, preferably above 580°C, and / or not above 750°C, not above 700°C, or not above 650°C. Higher T... g This can be advantageous in terms of crystallization stability, as it reduces the impact on T. max The temperature difference allows the glass to reach a stable glassy state more quickly. However, the glass can still be thermoformed and processed.

[0021] In an advantageous embodiment, the molar ratio of (TiO2+ZrO2+2*Nb2O5+2*Ta2O5+2*Al2O3+SiO2+B2O3) / (R2O+RO+2*Ln2O3) in the glass according to the invention is 1.5-3.5, wherein R2O = Li2O, Na2O and / or K2O, and RO = MgO, CaO, SrO and / or BaO, and Ln2O3 = Y2O3, La2O3, Gd2O3 and / or Yb2O3. Regarding the components TiO2, ZrO2, Nb2O5, and Ta2O... 5、 Al2O 3、The ratio of SiO2 and B2O3 to the components R2O, RO, and Ln2O3 should be carefully considered. The selection of these ratios must meet the conditions of this invention: the molar ratio of (TiO2 + ZrO2 + 2*Nb2O5 + 2*Ta2O5 + 2*Al2O3 + SiO2 + B2O3) / (R2O + RO + 2*Ln2O3) should be 1.5 - 3.5. If the ratio is too high, it may lead to undesirable crystallization and / or undesirable discoloration in the glass. If the ratio is too low, there is also a risk of undesirable crystallization. Preferably, the molar ratio of (TiO2+ZrO2+2*Nb2O5+2*Ta2O5+2*Al2O3+SiO2+B2O3) / (R2O+RO+2*Ln2O3) in the glass according to the present invention is 1.8-3.2, more preferably 2.0-3.0, and particularly preferably 2.1-2.9.

[0022] In an advantageous embodiment, the molar ratio of (TiO2+ZrO2+2*Nb2O5+2*Ta2O5+2*Al2O3+SiO2+B2O3) / (R2O+Cs2O+RO+2*Ln2O3) in the glass according to the invention is 1.5-3.5, wherein R2O = Li2O, Na2O and / or K2O, and RO = MgO, CaO, SrO and / or BaO, and Ln2O3 = Y2O3, La2O3, Gd2O3 and / or Yb2O 3。 Regarding the components TiO2, ZrO2, Nb2O5, and Ta2O 5、 Al2O 3、 The ratio of SiO2 and B2O3 to the components R2O, Cs2O, RO, and Ln2O3 should be carefully considered. The ratios must meet the conditions of this invention: the molar ratio of (TiO2 + ZrO2 + 2*Nb2O5 + 2*Ta2O5 + 2*Al2O3 + SiO2 + B2O3) / (R2O + Cs2O + RO + 2*Ln2O3) should be 1.5 - 3.5. If the ratio is too high, it may lead to undesirable crystallization and / or discoloration of the glass. If the ratio is too low, there is also a risk of undesirable crystallization. Preferably, the molar ratio of (TiO2+ZrO2+2*Nb2O5+2*Ta2O5+2*Al2O3+SiO2+B2O3) / (R2O+Cs2O+RO+2*Ln2O3) in the glass according to the present invention is 1.8-3.2, more preferably 2.0-3.0, and particularly preferably 2.1-2.9.

[0023] Preferably, the density r of the optical glass according to the present invention is not greater than 4.5 g / cm³. 3 Preferably, the concentration is not greater than 4.3 g / cm³. 3Preferably, the concentration is not greater than 4.1 g / cm³. 3 More preferably not greater than 4.0 g / cm³ 3 Preferably, the content is not greater than 3.90 g / cm³. 3 Furthermore, it is particularly preferred that the content be no greater than 3.85 g / cm³. 3 or not greater than 3.8 g / cm 3 Preferably, the glass according to the invention has a density of 3.0 g / cm³. 3 Up to 4.5 g / cm 3 Preferably 3.2 g / cm 3 Up to 4.3 g / cm 3 Preferably 3.5 g / cm 3 Up to 4.1 g / cm 3 A particularly preferred value is 3.6 g / cm³. 3 Up to 4.0 g / cm 3 3.6g / cm 3 Up to 3.85 g / cm 3 Or 3.6g / cm 3 Up to 3.8 g / cm 3 .

[0024] Preferably, the density r of the glass is related to its refractive index n. d The ratio (r / n) d The value is no greater than 2.0 g / cm³. 3 Preferably, the concentration is not greater than 1.95 g / cm³. 3 In some advantageous embodiments, the density r of the glass is related to its refractive index n. d The ratio (r / n) d (Not greater than 1.90 g / cm³) 3 Preferably, the concentration is not greater than 1.89 g / cm³. 3 or not greater than 1.88 g / cm 3 In some advantageous embodiments, the density r of the glass is related to its refractive index n. d The ratio (r / n) d The concentration is no greater than 1.87 g / cm³. 3 Preferably, the concentration is not greater than 1.86 g / cm³. 3 .

[0025] Preferably, the Abbe number v of the optical glass according to the present invention d The ratio of density r to (v) d / r) is 4.5cm 3 / g to 7.5cm 3 / g, preferably 4.8cm 3 / g to 7.0cm 3 / g, or preferably 4.9cm 3 / g to 6.5cm3 / g, particularly preferably 5.0cm 3 / g to 6.0cm 3 / g.

[0026] Preferably, the Abbe number v of the glass d The product of the product with density r is less than 100 g / cm³. 3 Preferably less than 95g / cm³ 3 Preferably less than 90g / cm 3 Preferably less than 80g / cm³ 3 And preferably greater than 50 g / cm³ 3 Preferably, it is greater than 55 g / cm³. 3 Preferably, it is greater than 60g / cm³. 3 Preferably, it is greater than 65g / cm³. 3 Particularly preferred is greater than 70 g / cm³ 3 .

[0027] According to the invention, the SiO2 content of the glass is less than 30.0 mol%. SiO2 is a glass forming agent. This oxide is very helpful for chemical resistance, but it increases the processing temperature. If the amount used is too large, the refractive index according to the invention cannot be achieved. Preferably, the glass contains at least 10.0 mol%, preferably at least 12.0 mol%, preferably at least 13.0 mol%, particularly preferably at least 15.0 mol% of SiO2. The glass contains less than 30.0 mol%, preferably no more than 28.0 mol%, more preferably no more than 25.0 mol%, particularly preferably no more than 23.0 mol% of SiO2. In an advantageous embodiment, the glass contains 10.0 mol% to < 30.0 mol%, preferably 12.0 mol% to 28.0 mol%, preferably 13.0 mol% to 25.0 mol%, more preferably 15.0 mol% to 23.0 mol% of SiO2.

[0028] B2O3 also acts as a glass-forming agent. In the glass system of this invention, B2O3 can help lower the temperature point T. max Preferably, the glass contains 0 mol% to 8.0 mol%, more preferably 0 mol% to 5.0 mol%, or 1.0 mol% to 5.0 mol% of B2O3. Some advantageous variations may contain at least 1.0 mol%, at least 1.5 mol%, or at least 2.0 mol% of B2O3. Preferably, the B2O3 content is limited to no more than 7.0 mol%, preferably no more than 6.5 mol%, preferably no more than 5.0 mol%, more preferably no more than 4.0 mol%, and preferably no more than 3.0 mol%. Some advantageous variations contain no more than 0.5 mol%, preferably less than 0.1 mol% of B2O3. Some advantageous variations do not contain B2O3.

[0029] Advantageously, the total amount of glass forgings should not be too low, as it promotes glass stability, and its content should be limited to obtain high-refractive-index glass. Preferably, the total content of SiO2 and B2O3 in the glass of the present invention is 12.0 mol% to 28.0 mol%, preferably 12.0 mol% to 25.0 mol%, preferably 15.0 mol% to 23.0 mol%.

[0030] The glass of the present invention may contain Nb₂O₅, but the use of Nb₂O₅ may lead to increased raw material costs and increased glass density. Therefore, according to the present invention, the Nb₂O₅ content is limited to less than 2.0 mol%, preferably less than 1.5 mol%, more preferably less than 1.0 mol%, and particularly preferably less than 0.5 mol%. Preferred embodiments of the glass of the present invention are substantially free of Nb₂O₅.

[0031] Preferably, the glass contains at least 35.0 mol%, preferably at least 37.0 mol%, preferably at least 40.0 mol%, or preferably at least 43.0 mol% and / or no more than 65.0 mol%, preferably no more than 61.0 mol%, or no more than 60.0 mol%, more preferably no more than 55.0 mol% of TiO2. In some advantageous embodiments, the glass contains 35.0 mol% to 65.0 mol%, preferably 40.0 mol% to 60.0 mol%, more preferably 43.0 mol% to 55.0 mol% of TiO2.

[0032] Preferably, the glass contains BaO in addition to TiO2, wherein the total content of BaO and TiO2 in the glass is preferably at least 35.0 mol%, preferably at least 40.0 mol%, or at least 42.0 mol%, or at least 45.0 mol%, more preferably at least 50.0 mol% and / or not more than 70.0 mol%, preferably not more than 65.0 mol%, preferably not more than 63.0 mol%, or not more than 60.0 mol%.

[0033] Optionally, the glass may contain Al2O3. Al2O3 can improve the chemical resistance of the glass. The glass may contain 0 to 8.0 mol%, 0 to 5.0 mol%, or up to 3.0 mol%, or up to 2.0 mol%, or up to 1.0 mol% of Al2O3. Some advantageous embodiments contain less than 0.5 mol% of Al2O3. 3。 Preferred variants do not contain Al2O3. Some advantageous variants may contain 0.5 mol% to 3.0 mol%, preferably 0.75 mol% to 2.5 mol% or 2.0 mol% to 5.0 mol% of Al2O3.

[0034] The glass may contain ZrO2. ZrO2 helps achieve a high refractive index, but it increases the glass's tendency to crystallize; therefore, its content is preferably limited to no more than 7.5 mol%, more preferably no more than 6.5 mol%, even more preferably no more than 5.5 mol% or no more than 5.0 mol%. In some advantageous embodiments, the glass contains at least 0.5 mol%, preferably at least 1.5 mol%, preferably at least 2.5 mol%, or 3.0 mol% of ZrO2. In some embodiments, the glass contains 0.5 mol% to 7.5 mol%, preferably 1.5 mol% to 6.5 mol%, more preferably 2.5 mol% to 5.5 mol%, and particularly preferably 3.0 mol% to 5.0 mol% of ZrO2. Some embodiments may not contain ZrO2.

[0035] Preferably, the glass contains Li₂O, Na₂O, and / or K₂O. Preferably, the total R₂O content in the glass is at least 1.0 mol%, more preferably at least 2.0 mol%, particularly preferably at least 3.0 mol% or at least 4.0 mol%, and / or no more than 20.0 mol%, preferably no more than 17.0 mol%, more preferably no more than 15 mol%, particularly preferably no more than 14 mol%, wherein R₂O = Li₂O, Na₂O, and / or K₂O. Preferably, the total R₂O content in the glass is from 1.0 mol% to 20 mol%, preferably from 2.0 mol% to 17.0 mol%, more preferably from 3.0 mol% to 15.0 mol%, and even more preferably from 4.0 mol% to 14 mol%. The above-mentioned alkali metal oxides contribute to good processing performance, but excessively high content may reduce chemical resistance and cause an excessive decrease in refractive index. Some embodiments may be R₂O-free.

[0036] In some advantageous embodiments, the glass comprises one of Li₂O, Na₂O, and K₂O. In some advantageous embodiments, the glass comprises at least two of Li₂O, Na₂O, and K₂O. In some advantageous embodiments, the glass comprises: Na₂O; and at least one of Li₂O and K₂O. In some embodiments, the glass comprises Li₂O, Na₂O, and K₂O.

[0037] In some embodiments, the glass contains Li₂O. Li₂O can corrode the materials of the crucible and furnace, therefore its content is preferably limited. The Li₂O content is preferably in the range of 0 mol% to 10.0 mol%, preferably 0.5 mol% to 7.0 mol%, more preferably 1.0 mol% to 5.0 mol%, 1.5 mol% to 3.0 mol%, or 1.5 mol% to 2.0 mol%. In some advantageous embodiments, the glass is Li₂O-free.

[0038] In an advantageous embodiment, the glass contains Na₂O. The Na₂O content is preferably from 0.5 mol% to 18.0 mol% or 0.5 mol% to 15.0 mol%, more preferably from 1.0 mol% to 13.5 mol%, or 1.0 mol% to 12.5 mol%. In some advantageous embodiments, the glass contains at least 1.0 mol%, preferably at least 1.5 mol%, preferably at least 2.0 mol%, at least 3.0 mol%, and / or no more than 18.0 mol% or no more than 15.0 mol%, preferably no more than 13.5 mol% or no more than 12.5 mol%, preferably no more than 11.0 mol% of Na₂O. In some advantageous embodiments, the glass may be Na₂O-free.

[0039] In some advantageous embodiments, the glass contains K2O, wherein the K2O content is less than 5.0 mol%, preferably less than 3.0 mol%, preferably in the range of greater than 0 mol% to 5.0 mol%, and preferably in the range of 0.5 mol% to 3.0 mol%. In some advantageous embodiments, the glass does not contain K2O.

[0040] In an advantageous embodiment, the glass contains at least one alkaline earth oxide, RO, wherein RO is selected from MgO, CaO, SrO, and / or BaO. Preferably, the glass contains at least BaO. More preferably, the glass contains: BaO; and at least one of MgO, CaO, and SrO. CaO and SrO can lower the melting temperature and improve the glass's crystallization stability without reducing the glass's chemical resistance like alkali metal oxides.

[0041] Preferably, the total content of MgO, CaO, and SrO is in the range of 2.0 mol% to 25.0 mol%. In some advantageous variations, the total content of MgO, CaO, and SrO in the glass is in the range of 5.0 mol% to 22.0 mol%. In some advantageous embodiments, the total content of MgO, CaO, and SrO is in the range of 5.0 mol% to 10.0 mol%. In some advantageous embodiments, the total content of MgO, CaO, and SrO is in the range of 12.0 mol% to 22.0 mol%.

[0042] In some advantageous embodiments, the glass contains: BaO; and at least one of MgO, CaO, and SrO, preferably MgO and / or CaO. Preferably, the total RO content in the glass is 5.0 mol% to 25.0 mol%, preferably 8.0 mol% to 31.0 mol%, preferably 10.0 mol% to 28.0 mol%, preferably 12.0 mol% to 24.0 mol%, wherein RO = MgO, CaO, SrO, and / or BaO.

[0043] Preferably, the glass contains BaO. Advantageously, the glass contains more than 0 mol% to 17.0 mol%, more than 0 mol% to 15.0 mol%, preferably 1.0 mol% to 12 mol% or 1.0 mol% to 13.0 mol%, more preferably 2.0 mol% to 11.0 mol% or 2.0 mol% to 13.0 mol% of BaO.

[0044] In some advantageous embodiments, the glass contains MgO in a content greater than 0 mol% to 10.0 mol%, preferably 0.5 mol% to 7.5 mol%, or 1.0 mol% to 6.0 mol%. Some advantageous variations contain MgO in a content greater than 0 mol% to 3.0 mol%, preferably 1.0 mol% to 3.0 mol%. Some advantageous variations do not contain MgO.

[0045] In an advantageous embodiment, the glass contains CaO. The CaO content is preferably in the range of greater than 0 mol% to 30.0 mol%, preferably in the range of 1.0 mol% to 25.0 mol%. In some advantageous embodiments, the glass contains 2.0 mol% to 22.0 mol%, preferably 3.0 mol% to 19.0 mol%, and even more preferably 5.0 mol% to 15.0 mol% of CaO. Some embodiments may be CaO-free.

[0046] The SrO content is preferably in the range of 0 mol% to 5.0 mol% or 0 mol% to 4.0 mol%. In some advantageous embodiments, the SrO content is in the range of 0 mol% to 3.0 mol% or 1.0 mol% to 3.0 mol%, preferably in the range of 1.5 mol% to 2.5 mol%. Some advantageous embodiments do not contain SrO.

[0047] Preferably, the total RO+R2O content in the glass is in the range of 15.0 mol% to 40.0 mol%, preferably 20.0 mol% to 35.0 mol%, and preferably 23.0 mol% to 31.0 mol%. Glass containing the specified total RO and R2O content exhibits good glass-forming properties. If the RO and R2O content is too low, the glass melting temperature is too high; if the RO and R2O content is too high, the glass crystallization tendency is increased.

[0048] Optionally, the glass may contain ZnO. However, ZnO is harmful to water quality and corrodes furnaces and crucibles, therefore the ZnO content is preferably limited to less than 10.0 mol%. In advantageous embodiments, the ZnO content in the glass is no more than 7.5 mol% or no more than 5.5 mol%, more preferably no more than 3.5 mol%. In some embodiments, the ZnO content in the glass is from 0.5 mol% to 7.5 mol%, preferably from 0.5 mol% to 5.5 mol%, more preferably from 0.75 mol% to 3.5 mol%. Some advantageous variations do not contain ZnO.

[0049] Optionally, the glass may contain Ln₂O₃, wherein Ln₂O₃ = La₂O₃, Gd₂O₃, Y₂O₃ and / or Yb₂O₃. Generally, these components can be used to increase the refractive index of the glass, but glasses containing Ln₂O₃ typically have a higher density. Therefore, the Ln₂O₃ content is limited to less than 5.0 mol%, preferably less than 2.0 mol%, more preferably less than 1.0 mol%, and particularly preferably less than 0.5 mol%. Preferably, the glass does not contain Ln₂O₃. 3。

[0050] Because the melt viscosity is low at the required melting temperature, there is no need to add traditional clarifying agents. Even if clarifying agents such as As₂O₃, Sb₂O₃, SO₃, F, and / or Cl are added, their content can be significantly reduced, for example, to < 0.1 mol%. Furthermore, it may be advantageous to use purely physical clarification methods. Optionally, in specific amounts (mol%), the glass may contain one or more of the following components with clarifying properties:

[0051] The glass may contain a small amount of sulfuric anhydride (SO3) to help stabilize the high oxidation state of polyvalent ions. If sulfuric anhydride is present, its content is at least 0.01 mol%. However, a higher content of sulfuric anhydride increases the risk of severe blistering of the glass and also increases the risk of platinum incorporation into the glass. Therefore, the content of sulfuric anhydride is preferably at most 0.5 mol%, preferably at most 0.1 mol%, and preferably at most 0.05 mol%. Preferably, the glass is free of SO3.

[0052] In some embodiments, F can stabilize the high oxidation state of multivalent ions, thereby having a positive impact on glass transmittance.

[0053] The glass may contain a small amount of hafnium (HfO2), preferably up to 0.2 mol%, more preferably up to 0.1 mol%, or up to 0.05 mol%. Generally, hafnium is not actively added, but rather introduced into the glass through the raw materials along with the ZrO2 component. When using high-purity ZrO2 raw materials, the glass preferably does not contain HfO2.

[0054] In a preferred embodiment, the glass comprises, by molar percentage:

[0055] In a preferred embodiment, the glass comprises, by molar percentage:

[0056] In a preferred embodiment, the glass comprises, by molar percentage:

[0057] In a preferred embodiment, the glass comprises, by molar percentage:

[0058] In a preferred embodiment, the glass comprises, by molar percentage:

[0059] In an advantageous embodiment, the glass comprises at least 95.0 mol%, particularly at least 98.0 mol%, or at least 99.0 mol%, of the components described herein, especially those listed in the table above. In one embodiment, the glass is substantially entirely composed of these components.

[0060] Preferably, the glass is substantially free of bismuth (Bi₂O₃) and / or lead (PbO). Adding bismuth disproportionately increases the glass density. Furthermore, even at relatively low temperatures of around 1000°C, bismuth ions are reduced to elemental bismuth, leading to severe ashing of the glass. PbO is excluded due to its negative impact on low density; moreover, PbO is a toxic component.

[0061] Due to the high content of niobium and titanium, the desired high refractive index glass can be obtained without the need for or with only the addition of precious components such as tantalum (Ta2O5) and / or tungsten (WO3) and / or germanium (GeO2).

[0062] Preferably, the glass is free of phosphates (P2O5), because phosphates cause the melt to exhibit significant reducing properties, and the reduction of TiO2 and / or Nb2O5 reduces transmittance. Furthermore, the reducing melt can corrode platinum, potentially causing platinum to enter the melt and leading to glass discoloration or increased scattering.

[0063] Optionally, given the respective cations, the glass is substantially free of one or more components selected from cadmium, gallium, germanium, thallium, coloring components (e.g., cobalt, vanadium, chromium, molybdenum, copper, nickel), and combinations thereof. The glass may contain trace amounts of iron, cerium, manganese, selenium, and / or tellurium, for example, as impurities. Iron, cerium, selenium, and tellurium, in particular, and manganese can be used as redox pairs. However, it is advantageous that these components should not be added to the glass, alone or in combination.

[0064] When this specification mentions that the glass does not contain a certain component or does not contain certain components, this component may exist in the glass as an impurity. This means that the component is added in a non-significant amount. According to the present invention, a non-significant amount means an amount less than 100 ppm, preferably less than 50 ppm, and most preferably less than 10 ppm (m / m).

[0065] Preferably, the net transmittance (t) of the glass is measured under conditions of a wavelength of 460 nm and a sample thickness of 10 mm. i (10mm, 460nm) is at least 80%, preferably at least 85%, more preferably at least 90%, and particularly preferably at least 93%.

[0066] Net transmittance, or net transmittance, can be measured using methods well known to those skilled in the art, such as according to standard DIN 5036-1:1978. In this specification, net transmittance refers to measurements taken at a wavelength of 460 nm and a sample thickness of 10 mm. The "sample thickness" specification does not indicate that the glass itself has that thickness, but only that the net transmittance data was measured under these thickness conditions.

[0067] Unless otherwise stated or obvious to those skilled in the art, all measurements described herein were performed at 20°C and 101.3 kPa atmospheric pressure.

[0068] On one hand, the present invention relates to a glass article comprising or composed of the glass described herein. The glass article may take different forms. Optionally, the article has the following forms: - Glass substrates, especially as part of a substrate stack, are used in optical components, particularly in AR glasses; - Wafers, especially wafers with a maximum diameter of 5.0 cm to 50.0 cm, or a diameter of 0.7 cm to 50 cm, preferably 3 cm to 45 cm or 5 cm to 40 cm; - Lenses, especially spherical lenses, cylindrical lenses, prisms, or aspherical lenses; and / or - Optical waveguides, especially optical fibers or planar waveguides.

[0069] On the other hand, the glass article described in this invention is a chemically tempered glass article, particularly a chemically tempered glass substrate, a chemically tempered wafer, and / or chemically tempered glass. Those skilled in the art will understand that the glass article comprises a chemically temperable optical glass according to the present invention.

[0070] Within the scope of this disclosure, chemically temperable glass should be understood as glass capable of undergoing an ion exchange process. In this process, alkali metal ion exchange occurs on the surface of a glass article (e.g., a wafer). Specifically, this is achieved by exchanging smaller ions for larger ions, thus creating a compressive stress zone in the surface. For this purpose, the glass article is immersed in a so-called ion exchange bath, such as a molten salt bath, containing larger ions, particularly potassium and / or sodium ions, causing these ions to migrate to the surface of the glass article. During the exchange, smaller ions (particularly lithium and / or sodium ions) migrate from the surface of the glass article into the ion exchange bath. This results in the formation of a compressive stress zone. This compressive stress zone can be described by the eigenvalue compressive stress (also known as "Compressive Stress" or abbreviated as "CS") and the compressive stress layer depth (also known as "Depth of Layer" or abbreviated as "DoL"). The compressive stress layer depth DoL is a concept well known to those skilled in the art, and within the scope of this disclosure, it refers to the depth at which the stress curve crosses the zero stress point.

[0071] Using this chemically tempered glass product can achieve higher mechanical strength.

[0072] Preferably, the preparation of the chemically tempered glass article includes the following steps: a) Provide the aforementioned glass products; b) Perform at least the first ion exchange; c) Optionally perform a second ion exchange.

[0073] Preferably, the first ion exchange is performed at a temperature of 350°C to 500°C, preferably 370°C to 450°C, particularly preferably 380°C to 430°C, for a duration of 0.5 hours to 24 hours, preferably 1 hour to 5 hours, more preferably 2 hours to 8 hours, wherein the exchange bath contains at least one potassium salt (especially KNO3) and / or at least one sodium salt (especially NaNO3).

[0074] In some advantageous embodiments, the duration of the subsequent second ion exchange is 0.5 hours to 24 hours, preferably 1 hour to 5 hours, more preferably 2 hours to 8 hours, at a temperature of 350°C to 500°C, preferably 370°C to 450°C, particularly preferably 380°C to 430°C, wherein the exchange bath contains at least one potassium salt (especially KNO3) and / or at least one sodium salt (especially NaNO3).

[0075] In another aspect, the present invention relates to the use of the glass or glass articles described herein in AR glasses, meta-optical elements, wafer-level optics, optical wafer applications, or classical optics. Alternatively or additionally, the glass or glass articles described herein can be used as wafers, lenses, or optical waveguides.

[0076] The glass of the present invention can be melted from commercially available raw materials. For example, the glass can be melted in the apparatus described in patent document DE102020120168A1. Detailed Implementation

[0077] The compositions shown in Tables 1 to 4 below were melted and their properties were tested.

[0078] Composition and properties: Table 1: Table 2: Table 3: Table 4: Table 5: Table 6 The glass according to embodiments of the present invention has low density, high refractive index, excellent Abbe number and density product, and low Tg. max Within the scope of this invention, the glass of this invention has been found to exhibit a lower tendency to crystallize.

[0079] Although the present invention is described based on preferred embodiments, the present invention is not limited thereto and can be modified in various ways.

Claims

1. An optical glass having a refractive index n d greater than 1.85, an Abbe number v d less than 35, a temperature T max not higher than 1350°C, said optical glass comprising at least Si02 and Ti02, wherein Si02 is contained in an amount less than 30.0 mol%, Nb205 is contained in an amount less than 2.0 mol%, BaO is contained in an amount less than 17 mol%, and Ln203 is contained in an amount less than 5.0 mol%, wherein, Ln203= Y203, La203, Gd203and / or Yb203.

2. The optical glass according to claim 1, wherein the glass has a molar ratio of (Ti02+ Zr02+ 2*Nb205+ 2*Ta205+ 2*Al203+ Si02+ B203) / (R20 + RO + 2*Ln203) of 1.5 - 3.5, wherein R20 = Li20, Na20 and / or K20, RO = MgO, CaO, SrO and / or BaO, and Ln203= Y203, La203, Gd203and / or Yb203.

3. The optical glass according to claim 1 or 2, wherein Abbe number V of the glass d a product with the density r of less than 120 g / cm 3 , preferably less than 100 g / cm 3 , particularly preferably less than 90 g / cm 3 and preferably more than 50 g / cm 3 , preferably more than 55 g / cm 3 , particularly preferably more than 60 g / cm 3 .

4. The optical glass according to any one of the preceding claims, wherein, The glass is essentially free of Nb205.

5. The optical glass according to any one of the preceding claims, wherein, The glass contains BaO in a total amount of at least 35.0 mol%, preferably at least 40.0 mol%, preferably at least 45.0 mol% and / or not more than 70.0 mol%, preferably not more than 65.0 mol%.

6. The optical glass according to any one of the preceding claims, wherein, The glass contains BaO in a total amount of at least 35.0 mol%, preferably at least 40.0 mol%, preferably at least 45.0 mol% and / or not more than 70.0 mol%, preferably not more than 65.0 mol%.

7. The optical glass according to any one of the preceding claims, wherein, The glass contains R20 in a total amount of 1.0 mol% to 20.0 mol%, preferably 2.0 mol% to 17 mol%, particularly preferably 3.0 mol% to 15.0 mol%, wherein R20 = Li20, Na20 and / or K20.

8. The optical glass according to any one of the preceding claims, wherein, The glass contains RO in a total amount of 8.0 mol% to 31.0 mol%, preferably 10.0 mol% to 28.0 mol%, wherein RO = MgO, CaO, SrO and / or BaO, and / or the glass contains MgO, CaO and SrO in a total amount of 2.0 mol% to 25.0 mol%, preferably 5.0 mol% to 22.0 mol%.

9. The optical glass according to any one of the preceding claims, wherein, The glass contains RO in a total amount of 8.0 mol% to 31.0 mol%, preferably 10.0 mol% to 28.0 mol%, wherein RO = MgO, CaO, SrO and / or BaO, and / or the glass contains MgO, CaO and SrO in a total amount of 2.0 mol% to 25.0 mol%, preferably 5.0 mol% to 22.0 mol%.

10. The optical glass according to any one of the preceding claims, wherein, The glass contains RO + R20 in a total amount of 15.0 mol% to 40.0 mol%, preferably 20.0 mol% to 35.0 mol%, particularly preferably 23.0 to 31.0 mol%.

11. The optical glass according to any one of the preceding claims, wherein, The glass contains Zr02in an amount of 0.5 mol% to 7.5 mol%, preferably 1.5 mol% to 6.5 mol%, more preferably 2.5 mol% to 5.5 mol%.

12. The optical glass according to any one of the preceding claims, wherein, The glass contains ZnO in an amount of less than 10.0 mol%, preferably not more than 7.5 mol%, particularly preferably 0.5 mol% to 5.5 mol%. 。 13. The optical glass according to any one of the preceding claims, wherein, The glass comprises the following components in mol%:

14. The optical glass according to any one of the preceding claims, wherein, The glass contains Si02and B203in a total amount of 12.0 mol% to 25.0 mol%, preferably 15.0 mol% to 23.0 mol%.

15. The optical glass according to any one of the preceding claims, wherein, The glass contains K20 in an amount of less than 5.0 mol%, preferably less than 3.0 mol%. 。 16. The optical glass according to any one of the preceding claims, wherein, The glass comprises the following components in mol%: 。 17. The optical glass according to any one of the preceding claims, wherein, The glass comprises the following components in mol%: The glass has a net transmittance of at least 80%, preferably at least 85%, more preferably at least 90%, particularly preferably at least 93%, measured at a wavelength of 460 nm and a sample thickness of 10 mm.

18. A glass article comprising the optical glass according to at least one of the preceding claims, in the form of: - a glass substrate, especially as part of a substrate stack, for optical elements, especially in AR glasses; - a wafer, especially with a maximum diameter of 5.0 cm to 50.0 cm, or a diameter of 0.7 cm to 50 cm, preferably 3 cm to 45 cm or 5 cm to 40 cm; - a lens, especially a spherical lens, a cylindrical lens, a prism or an aspherical lens; and / or - an optical waveguide, especially an optical fiber or a slab waveguide.

19. Use of the optical glass or glass article according to at least one of the preceding claims in AR glasses, super-structured optical elements, wafer-level optics, optical wafer applications, or classical optics; and / or as a wafer, a lens or an optical waveguide.

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