High-refraction glass having low density

Abstract

To provide an optical glass having a refractive index of more than 1.95, glass articles including the optical glass and the use thereof, especially in the fields of optics and lenses, metaoptics and augmented reality (AR).SOLUTION: An optical glass having a refractive index nd of more than 1.95, preferably 2.05 or less, an Abbe number vd of less than 32, and a temperature Tmax of 1350°C or lower, the optical glass comprising at least SiO2, TiO2, and Nb2O5, containing less than 30.0 mol% of SiO2, less than 5.0 mol% of ZnO, and less than 5.0 mol% of Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3, and / or Yb2O3.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an optical glass having a refractive index greater than 1.95, to glass articles comprising this optical glass, and to its uses, in particular in the fields of optical systems and lenses, meta-optics and "Augmented Reality" (AR).

[0002] The present invention deals with glasses that can be used in the field of augmented reality (AR). High-index glasses, i.e., glasses with a high refractive index, are advantageous for AR glasses because they widen the field of view (FoV). On the other hand, the density of such glasses often increases disproportionately with the increase in refractive index. This means that even if there were a means to thin wafers for AR applications, the eyeglass glass would become significantly heavier, thereby making AR glasses uncomfortable to wear for long periods of time. As the trend shifts from headsets to standard eyeglass forms and the desire for longer or constant wear like regular glasses increases, the glasses need to be lighter. This weight reduction is also advantageous for many other areas of use, since camera optics in the digital single-lens reflex (DSLR) field are also very often either very bulky or very heavy, thereby significantly increasing the battery performance required for autofocus.

[0003] Some prior art glasses are derived from niobium phosphate or titanium phosphate systems, i.e., they contain significant proportions of P2O5 and niobium or titanium. These glasses are particularly problematic during production, in part because lower oxidation states are created by oxygen loss, such as high melting and refining temperatures, in the already reducing phosphate systems. For example, in the case of niobium, this is an oxidation state below V, and in the case of titanium, it is below IV. This can result in dark brown to black coloring in niobium systems, or blue, yellow-green to brown, or even black coloring in titanium systems. Furthermore, titanium significantly increases the tendency to crystallize, a known problem for existing higher refractive index glasses in the heavy flint sector, which, for example, can no longer be repressed. In contrast to niobium, even titanium in its highest oxidation state absorbs at the edge of the visible range, thereby causing the known yellow tint of barium titanium silicate at higher concentrations.

[0004] Furthermore, niobium phosphate glass families, such as the high refractive index heavy flint or lanthanum heavy flint families, are not only prone to interfacial crystallization but also exhibit very rapid crystal growth, which makes post-cooling (stress cooling or index tuning) important in some cases for pre-nucleated glasses. Furthermore, the glasses have proven relatively brittle and are therefore difficult to polish into very thin wafers.

[0005] On the other hand, the weathering resistance is relatively good, at least for niobium phosphate glasses, despite the P2O5, and the density is very low for this high refractive index, which increases the wearing comfort. These families are known from the literature.

[0006] Commercially available lanthanum heavy flint systems in the refractive index range of interest for AR applications have refractive indices n dThese glasses have a significantly unfavorable combination of viscosity and density. The relatively high density and high Abbe number of these glasses are caused, in particular, by the high content of lanthanum oxide. Furthermore, such glasses have a relatively high hardness, which increases the cost of wafer production by increasing the grinding time. Furthermore, in some cases, the cost of raw glass is already significantly high due to the use of tungsten oxide, tantalum oxide, and other expensive raw materials from the rare earth field during production. In the heavy flint field, Nb2O5 is often a batch cost factor, while other raw materials, even of optical quality, are relatively inexpensive in comparison. Furthermore, available lanthanum heavy flint glasses are often alkali oxide-free and therefore not chemically hardenable. However, depending on the application area, it may be advantageous to increase the mechanical stability of optical components (e.g., eyeglass glasses) for AR applications, which may become increasingly thin, by chemical hardening.

[0007] Many heavy flint glasses in this region of the Abbe diagram, such as P-SF glass, are problematic on the one hand due to their batch cost, and, in addition, due to their high Bi2O3 content, are very soft (=scratch-sensitive) and have unfavorable UV edges in their transmission, e.g., UV edges that are not steep enough and / or UV edges that are shifted to the longer wavelength region of the spectrum. In particular, P-SF glasses are furthermore produced discontinuously in platinum crucibles, which can lead to problems due to platinum alloying and reduction of Bi(III) to Bi(0) in the bath.

[0008] As mentioned earlier, there are some more or less suitable glasses, but these are often still in a range of refractive index that is too low (typical heavy flint glasses) or are difficult to process or handle (typical lanthanum heavy flint glasses).

[0009] The object of the present invention is to provide a high refractive index n dThe objective is to provide a glass that has the lowest possible density at the same time. The glass must exhibit the highest possible pure transmittance, be easily hot-formed, and be easily processable. To this end, the hardness must not be too low (resulting in more scratches and microcracks), but also not too high (resulting in longer grinding times, which in turn results in microcracks). The glass must have high chemical resistance.

[0010] In one aspect, the present invention provides an optical glass having a refractive index n greater than 1.95, preferably less than or equal to 2.05. d , Abbe number v less than 32 d , and temperatures T below 1350 °C max and containing at least SiO2, TiO2 and Nb2O5, and containing less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3 = Y2O3, La2O3, Gd2O3 and / or Yb2O3, and the glass satisfies at least one of the following conditions: (i) a K2O content greater than 0 mol%; (ii) a B2O3 content of 0.5 mol% or less; (iii) a molar ratio of B2O3 to SiO2 of at least 0.09 The present invention relates to optical glass that satisfies the above requirements.

[0011] In an advantageous embodiment, the invention relates to an optical glass having a refractive index n greater than 1.95, preferably less than or equal to 2.05. d , Abbe number v less than 32 d , and temperatures T below 1350 °C max and comprising at least SiO2, TiO2 and Nb2O5, less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3 and / or Yb2O3, and having a K2O content greater than 0 mol%.

[0012] In an advantageous embodiment, the invention relates to an optical glass having a refractive index n greater than 1.95, preferably less than or equal to 2.05. d , Abbe number v less than 32 d , and temperatures T below 1350 °C max and comprising at least SiO2, TiO2 and Nb2O5, less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3 and / or Yb2O3, and having a K2O content greater than 0 mol% and a B2O3 content of 0.5 mol% or less, preferably being B2O3-free.

[0013] In an advantageous embodiment, the invention relates to an optical glass having a refractive index n greater than 1.95, preferably less than or equal to 2.05. d , Abbe number v less than 32 d , and temperatures T below 1350 °C max and comprising at least SiO2, TiO2 and Nb2O5, and comprising less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3 and / or Yb2O3, and the glass has a K2O content greater than 0 mol% and a molar ratio of B2O3 to SiO2 of at least 0.09.

[0014] In an advantageous embodiment, the invention relates to an optical glass having a refractive index n greater than 1.95, preferably less than or equal to 2.05. d , Abbe number v less than 32 d , and temperatures T below 1350 °C max and comprising at least SiO2, TiO2 and Nb2O5, less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3 and / or Yb2O3, and the glass has a B2O3 content of 0.5 mol% or less, and is preferably B2O3-free.

[0015] In an advantageous embodiment, the invention relates to an optical glass having a refractive index n greater than 1.95, preferably less than or equal to 2.05. d , Abbe number v less than 32 d , and temperatures T below 1350 °C max and comprising at least SiO2, TiO2 and Nb2O5, less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3 and / or Yb2O3, and the glass has a molar ratio of B2O3 to SiO2 of at least 0.09.

[0016] Within the scope of the present invention, a glass system comprising TiO and NbO with SiO is found, which, compared to glasses from the niobium phosphate or titanium phosphate systems described at the outset, is more stable in terms of the achievable internal transmittance, has a higher refractive index, but has a relatively low density. Furthermore, this glass system has a higher hardness than the niobium phosphate glasses described.

[0017] The optical glass according to the present invention has a refractive index n greater than 1.95, preferably less than or equal to 2.05. d It has.

[0018] In an advantageous embodiment, the refractive index n d is greater than 1.950, preferably at least 1.955, 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. d The upper limit may be 2.05, or 2.050, or 2.045, or 2.040, or 2.035, or 2.030, or 2.025, or 2.020. Overall, the refractive index is therefore advantageously in the range of more than 1.95 to 2.05. The refractive index n d is known to those skilled in the art and specifically refers to the refractive index at a wavelength of about 587.6 nm (the wavelength of the d-line of helium). dIt is known to those skilled in the art how this can be determined.

[0019] The refractive index is preferably determined by a refractometer, particularly a V-block refractometer. In this case, samples with a square or nearly square base (e.g., dimensions of approximately 20 mm x 20 mm x 5 mm) can be used. When measuring with a V-block refractometer, the sample is typically placed in a V-block prism with a known refractive index. The refraction of the incident light beam depends on the difference between the refractive index of the sample and that of the V-block prism, and thus the refractive index of the sample can be determined. Measurements are preferably performed at a temperature of 22°C.

[0020] According to the invention, the glass has an Abbe number, i.e., dispersion (v d In advantageous embodiments, the variance is less than 30 or less than 25, preferably less than 24 or less than 23, and / or greater than 18, preferably greater than 18.5, more preferably greater than 19.0, more preferably greater than 19, 5 and / or 20. d is the refractive index n measured by a refractometer. d (at approximately 587.6 nm), n F (at about 486 nm) and n C (at about 656 nm) and correlate them using known techniques: v d =(n d -1) / (n F -n C ) It is calculated as follows.

[0021] Furthermore, the glass according to the present invention can be cured at a temperature T max T maxis a composition-dependent glass variable that indicates the minimum temperature required in the melting process to produce a "perfect" melt from the starting materials (e.g., raw material cullet). Here, a "perfect" melt exists when no melt residues (e.g., raw materials that are not completely melted) are found and no crystals are found in the melt. As explained in the introduction, the melting and refining temperatures should be as low as possible to avoid the introduction of refractory materials into the glass and the coloring of the glass by polyvalent ions in low oxidation states. This allows a high pure transmittance to be achieved. Since the melting and refining temperatures cannot be chosen arbitrarily high due to the requirement to reach the highest possible pure transmittance, there is an upper limit to the melting temperature, and therefore the temperature points mentioned here are referred to as "T max ". Therefore, T max is the lowest temperature at which a crystal-free complete melt can still be produced. max is a good measure of the liquidus temperature of the glass (see below).

[0022] Within the scope of the present invention, the T max is systematically determined on a laboratory scale in a series of tests by melting the same glass from the starting components, each with a volume of 20 ml, in small crucibles at different maximum temperatures, with temperature steps of 10°C chosen. The melting result is then evaluated optically, starting from the lowest temperature up to the highest, to see whether a complete melt has already formed or whether residues and / or crystals are still visible in the glass.

[0023] The T determined for the composition by this method max The values ​​could be reproduced for larger volumes (e.g., 1 liter) of laboratory melt. Furthermore, further testing revealed that the temperature point T max It has been shown that the temperature T is only slightly higher than the liquidus temperature of glass. max has been found to be a good measure of the liquidus temperature in the glass, which has not been precisely determined here.

[0024] In a further advantageous configuration of the invention, T max is less than or equal to 1330°C, advantageously less than or equal to 1320°C, preferably less than or equal to 1310°C, preferably less than or equal to 1300°C. Some advantageous variants have a T of less than or equal to 1290°C or less than or equal to 1280°C. max It has.

[0025] In an advantageous embodiment, the glass has a glass transition temperature T g Preferably, T g may be above 540°C, advantageously above 560°C, preferably above 580°C, and / or below 750°C, below 700°C or below 650°C. g The higher the max This may be advantageous in terms of crystallization stability, since the temperature difference between the glass and the glass is smaller and the glass reaches a stable glass state more quickly, however the glass can still be hot formed and processed well.

[0026] In an advantageous embodiment, the glass according to the invention comprises a molar ratio (TiO2 + ZrO2 + 2 * Nb2O5+2 * Ta2O5+2 * Al2O3+SiO2+B2O3) / (R2O+RO+2 * Ln2O3), where R2O = Li2O, Na2O and / or K2O, RO = MgO, CaO, SrO and / or BaO, and Ln2O3 = Y2O3, La2O3, Gd2O3 and / or Yb2O3. Regarding the ratio of the proportions of the components TiO2, ZrO2, Nb2O5, Ta2O5, Al2O3, SiO2 and B2O3 to the proportions of the components R2O, RO and Ln2O3, these proportions should be within the range of 1.5 to 3.5 under the conditions according to the invention (TiO2 + ZrO2 + 2 * Nb2O5+2 * Ta2O5+2 * Al2O3+SiO2+B2O3) / (R2O+RO+2 *It should be noted that the molar ratio should be selected so that the ratio of TiO2 + ZrO2 + Ln2O3 is satisfied. At higher ratios, there is a risk of undesired crystallization and / or undesired discoloration of the glass. If the ratio is too low, there is also a risk of undesired crystallization. Preferably, the glasses according to the invention have a molar ratio (TiO2 + ZrO2 + 2 * Nb2O5+2 * Ta2O5+2 * Al2O3+SiO2+B2O3) / (R2O+RO+2 * Ln2O3).

[0027] In an advantageous embodiment, the glass according to the invention comprises a molar ratio (TiO2 + ZrO2 + 2 * Nb2O5+2 * Ta2O5+2 * Al2O3+SiO2+B2O3) / (R2O+Cs2O+RO+2 * Ln2O3), where R2O = Li2O, Na2O and / or K2O, R0 = MgO, CaO, SrO and / or BaO, and Ln2O3 = Y2O3, La2O3, Gd2O3 and / or Yb2O3. Regarding the ratio of the proportions of the components TiO2, ZrO2, Nb2O5, Ta2O5, Al2O3, SiO2 and B2O3 to the proportions of the components R2O, Cs2O, R0 and Ln2O3, these proportions should be within the range of 1.5 to 3.5 under the conditions according to the invention (TiO2 + ZrO2 + 2 * Nb2O5+2 * Ta2O5+2 * Al2O3+SiO2+B2O3) / (R2O+Cs2O+RO+2 * It should be noted that the molar ratio should be selected so that the ratio of TiO2 + ZrO2 + Ln2O3 is satisfied. At higher ratios, there is a risk of undesired crystallization and / or undesired discoloration of the glass. If the ratio is too low, there is also a risk of undesired crystallization. Preferably, the glasses according to the invention have a molar ratio (TiO2 + ZrO2 + 2 * Nb2O5+2 * Ta2O5+2 *Al2O3+SiO2+B2O3) / (R2O+Cs2O+RO+2 * Ln2O3).

[0028] Preferably, the optical glass according to the present invention has a viscosity of 4.5 g / cm 3 or less, preferably 4.3 g / cm 3 or less, preferably 4.1 g / cm 3 or less, more preferably 4.0 g / cm 3 Preferably, the density of the glass according to the invention is less than 3.0 g / cm 3 ~4.5g / cm 3 , preferably 3.2 g / cm 3 ~4.3g / cm 3 , preferably 3.5 g / cm 3 ~4.1g / cm 3 , particularly preferably 3.6 g / cm 3 ~4.0g / cm 3 is.

[0029] Preferably, the glass has a viscosity of 2.0 g / cm 3 or less, preferably 1.97 g / cm 3 or less, preferably 1.95 g / cm 3 Density ρ vs. refractive index n d The ratio (ρ / n d In some advantageous embodiments, the glass has a viscosity of 1.93 g / cm 3 or less, preferably 1.92 g / cm 3 or less, or 1.91 g / cm 3 Density ρ vs. refractive index n d The ratio (ρ / n d In some advantageous embodiments, the glass has a viscosity of 1.90 g / cm 3 or less, preferably 1.89 g / cm 3 Density ρ vs. refractive index n d The ratio (ρ / n d )

[0030] Preferably, the optical glass according to the present invention is 4.5 cm 3 / g~7.5cm 3 / g, preferably 4.8 cm 3 / g~7.3cm 3 / g, or preferably 5.0 cm 3 / g~7.0cm 3 / g, particularly preferably 5.1 cm 3 / g~6.5cm 3 Abbe number v / g d Ratio of density ρ (v d / ρ).

[0031] Preferably, the glass has a density of 120 g / cm 3 less than 100 g / cm 3 less than 90 g / cm 3 less than, and preferably 50 g / cm 3 More than 55 g / cm 3 More than 60 g / cm 3 Abbe number v d and density ρ.

[0032] According to the present invention, the glass has an SiO2 content of less than 30.0 mol%. SiO2 is a glass former. Oxides contribute significantly to chemical resistance, but also increase the processing temperature. If too much oxide is used, the refractive index according to the present 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%, at least 15.0 mol%, at least 17.0 mol%, at least 19.0 mol%, or at least 22.0 mol% of SiO2. The glass has an SiO2 content of less than 30.0 mol%, preferably 29.5 mol% or less, preferably 27.0 mol% or less, particularly preferably 25.0 mol% or less, 23.0 mol% or less, or 20.0 mol% or less. In an advantageous embodiment, the glass contains 13.0 mol% to less than 30.0 mol%, preferably 13.0 mol% to 29.5 mol%, preferably 15.0 mol% to 27.0 mol% or up to 25.0 mol% SiO2.

[0033] B2O3 acts as a glass former as well. In the glass system according to the invention, B2O3 is present at a temperature point Tmax This can contribute to reducing the BO3 content. Preferably, the glass contains 0 mol% to 8.0 mol%, preferably 0 mol% to 5.0 mol%, or 1.0 mol% to 5.0 mol% BO3. Some advantageous variations may contain at least 1.0 mol%, or at least 1.5 mol%, or at least 2.0 mol% BO3. Preferably, the BO3 content is limited to 7.0 mol% or less, preferably 6.5 mol% or less, preferably 5.0 mol% or less, more preferably 3.0 mol% or less, preferably 2.0 mol% or less. Some advantageous variations have a B2O3 content of 1.0 mol% to 6.5 mol%, preferably 1.5 mol% to 5.0 mol%, or preferably 2.0 mol% to 3.0 mol%, and / or a B2O to SiO2 molar ratio of at least 0.09, preferably at least 0.10, more preferably at least 0.12, preferably at least 0.15 or 0.20, and preferably less than 0.50, preferably less than 0.45, more preferably less than 0.35, and particularly preferably less than 0.30. Some advantageous variations contain 0.5 mol% or less B2O3, preferably less than 0.1 mol%. Some advantageous variations are B2O3-free.

[0034] The glasses of the present invention contain Nb2O5 and TiO2. Niobium-containing glasses are known to exhibit poorer net transmittance in the near-UV-visible spectral range and to have a strong tendency toward interface crystallization in the presence of TiO2. These drawbacks do not occur in the glasses described herein, or occur only to a controllable extent. These components result in a high refractive index at moderate and reduced densities. Preferably, the glasses have a molar ratio of Nb2O5 to TiO2 of less than 0.9, more preferably less than 0.7, particularly preferably less than 0.6, and / or at least 0.05, preferably at least 0.06, even more preferably at least 0.07, or at least 0.25. Some advantageous variations have a molar ratio of Nb2O5 to titanium of 0.05 to 0.25, preferably 0.07 to 0.20. Some advantageous variations have a molar ratio of Nb2O5 to TiO2 between 0.25 and 0.9, preferably between 0.3 and 0.7, and even more preferably between 0.35 and 0.65 or even up to 0.60.

[0035] Preferably, the glass contains at least 1.5 mol%, preferably at least 2.0 mol%, preferably at least 5.0 mol%, at least 7.0 mol%, at least 8.0 mol%, or at least 10.0 mol%, and / or up to 17.0 mol%, preferably up to 15.0 mol%, preferably up to 12.0 mol%, 10.0 mol%, or up to 9.0 mol% Nb2O5. In some embodiments, the glass contains 2.0 mol% to 10.0 mol%, preferably 3.5 mol% to 9.0 mol% Nb2O5. In some advantageous embodiments, the glass contains 5.0 mol% to 17.0 mol%, preferably 6.0 mol% to 15.0 mol%, or 8.0 mol% to 17.0 mol%, also preferably 10.0 mol% to 15.0 mol% Nb2O5.

[0036] Preferably, the glass contains at least 18.0 mol%, preferably at least 20.0 mol%, or preferably at least 23.0 mol%, more preferably at least 25.0 mol%, and / or not more than 55.0 mol%, preferably not more than 50.0 mol%, and even more preferably not more than 48.0 mol% TiO2. In some embodiments, the glass contains at least 30.0 mol%, preferably at least 35.0 mol%, more preferably at least 40.0 mol%, and / or not more than 55.0 mol%, preferably not more than 50.0 mol%, and even more preferably not more than 48.0 mol% TiO2. In some advantageous embodiments, the glass contains 35.0 mol% to 55.0 mol%, preferably 40.0 mol% to 50.0 mol%, and even more preferably 42.0 mol% to 48.0 mol% TiO2. In some advantageous embodiments, the glass contains 20.0 to 35.0 mol %, preferably 23.0 mol % or 25.0 mol % to 30.0 mol % TiO2.

[0037] Preferably, the glass comprises not only Nb2O5 and TiO2 but also BaO, and the glass preferably has a total content of BaO, Nb2O5 and TiO2 of at least 40.0 mol%, preferably at least 43.0 mol% or at least 45.0 mol%, even more preferably at least 50.0 mol%, and / or not more than 65.0 mol%, preferably not more than 62.0 mol%, preferably not more than 60.0 mol%.

[0038] Optionally, the glass may contain Al2O3. Al2O3 can contribute to the chemical resistance of the glass. The glass may contain 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. Preferred variations are Al2O3-free. Some advantageous variations may contain 0.5 mol% to 3.0 mol%, preferably 0.75 mol% to 2.5 mol%.

[0039] The glass may contain ZrO2. While ZrO2 contributes to achieving a high refractive index, ZrO2 also increases the crystallization tendency of the glass, so its content is preferably limited to 5.5 mol% or less, preferably 5.0 mol% or less, also preferably 4, 5 mol% or less, or 4.0 mol% or less, more preferably 3.5 mol% or less, or 3.0 mol% or less. In some advantageous embodiments, the glass contains 1.5 mol% to 5.5 mol% or up to 5.0 mol%, preferably 2.0 mol% to 4.0 mol% ZrO2. Some embodiments are ZrO2-free.

[0040] Preferably, the glass contains Li2O, Na2O, and / or K2O. Preferably, the glass has a total content of R2O, where R2O = Li2O, Na2O, and / or K2O, greater than 0 mol%, preferably at least 2.0 mol%, more preferably at least 4.0 mol%, particularly preferably at least 8.0 mol% or at least 10 mol%, and / or up to 25.0 mol%, preferably up to 23.0 mol%. The aforementioned alkali metal oxides contribute to good processability, but too high a content can reduce chemical resistance and significantly lower the refractive index. Some embodiments are R2O-free.

[0041] In some advantageous embodiments, the glass comprises one of LiO, NaO, and KO. In some advantageous embodiments, the glass comprises at least two of LiO, NaO, and KO. In some advantageous embodiments, the glass comprises KO and at least one of LiO and NaO. In some embodiments, the glass comprises LiO, NaO, and KO.

[0042] In some embodiments, the glass contains Li2O. Because Li2O may affect the materials of the crucible and the vessel, its content is preferably limited. The Li2O content is preferably 0 mol% to 23.0 mol%, preferably up to 21.0 mol%, more preferably up to 18.0 mol%, up to 17.0 mol%, or up to 16.0 mol%, and even more preferably up to 15.0 mol%. In some advantageous embodiments, the glass contains 0 mol% or at least 1.0 mol%, preferably at least 3.0 mol% or at least 4.0 mol%, and / or up to 5.0 mol%, preferably up to 3.5 mol%, up to 3.0 mol%, and particularly preferably up to 2.0 mol% Li2O. In some embodiments, the glass contains at least 5.0 mol% and up to 17.0 mol%, preferably up to 15.0 mol%, more preferably up to 12.0 mol% or up to 10.0 mol%, and even more preferably up to 7.5 mol% Li2O. In some advantageous embodiments, the glass is Li2O-free.

[0043] In some advantageous embodiments, the glass contains Na2O. The Na2O content is preferably in the range of 0 mol% to 15.0 mol%, preferably 1.0 mol% to 12.5 mol% or 12.0 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%, at least 4.0 mol%, or at least 5.0 mol%, and / or no more than 15.0 mol%, preferably no more than 12.5 mol%, or no more than 12.0 mol%, preferably no more than 10.0 mol%, no more than 8.0 mol%, or no more than 6.0 mol% Na2O. In some advantageous embodiments, the glass contains no more than 5.0 mol%, no more than 4.0 mol%, or no more than 3.0 mol% Na2O. In some advantageous embodiments, the glass is Na2O-free.

[0044] In some advantageous embodiments, the glass contains K2O. The K2O content is preferably 0 mol% or greater than 0 mol% to 12.0 mol%, preferably in the range of 1.0 mol% to 10.0 mol%. In some advantageous embodiments, the glass contains at least 1.0 mol%, at least 2.0 mol%, or at least 3.0 mol%, and / or 10.0 mol% or less, preferably 8.0 mol% or less or 6.0 mol% or less, and more preferably 5.0 mol% or less or 4.0 mol% or less of K2O. In some advantageous embodiments, the glass is free of K2O.

[0045] In an advantageous embodiment, the glass contains at least one alkaline earth metal oxide RO, where RO is selected from MgO, CaO, SrO, and / or BaO. Preferably, the glass contains at least BaO. Preferably, the glass contains BaO and at least one of MgO, CaO, and SrO. CaO and SrO lower the melting temperature and stabilize the glass against crystallization without reducing chemical resistance to the same extent as alkali metal oxides.

[0046] Preferably, the total content of MgO, CaO and SrO is in the range of from greater than 0 mol% to 30.0 mol%, or from greater than 0 mol% to 25.0 mol%, preferably in the range of from 2.0 mol% to 20.0 mol%. In some advantageous variants, the glass contains a total content of MgO, CaO and SrO in the range of from 3.0 mol% to 15.0 mol%.

[0047] In some advantageous embodiments, the glass contains BaO and at least one of MgO, CaO, and SrO, preferably MgO and / or CaO. Preferably, the glass has a total content of RO, where RO=MgO, CaO, SrO, and / or BaO, of 2.0 mol% to 40.0 mol%, preferably 5.0 mol% to 35.0 mol%, preferably 6.0 mol% to 30.0 mol%, or 6.0 mol% to 25.0 mol%. In some advantageous embodiments, the glass contains a total content of MgO, CaO, SrO, and BaO of 18.0 mol% to 30.0 mol%, preferably 19.0 mol% to 27.0 mol%, more preferably 20.0 mol% to 26.0 mol%, or 21.0 mol% to 25.0 mol%. In some advantageous embodiments, the glass contains MgO, CaO, SrO and BaO in a total content of 5.0 mol % to 20.0 mol %, preferably 8.0 mol % to 18.0 mol %, and even more preferably 10.0 mol % to 15.0 mol %.

[0048] Preferably, the glass contains BaO. Advantageously, the glass contains 3.5 mol% to 15.0 mol%, preferably 4.0 mol% to 13.0 mol%, even more preferably 4.0 mol% to 11.0 mol%, and even more preferably 4.5 mol% to 10.0 mol% BaO. In some embodiments, the glass contains at least 3.5 mol%, preferably at least 4.0 mol%, at least 4.5 mol%, or at least 5.0 mol%, and / or no more than 12.0 mol%, preferably no more than 11.0 mol%, also preferably no more than 10.0 mol% or no more than 8.0 mol% BaO.

[0049] The MgO content is preferably in the range of 0 mol% to 5.0 mol%, preferably 0.5 mol% to 4.5 mol%, or 1.0 mol% to 3.0 mol%. Some advantageous variations contain less than 3.0 mol%, preferably less than 2.0 mol% MgO. Some advantageous variations are MgO-free.

[0050] The CaO content is preferably in the range of 0 mol% to 30.0 mol%, preferably 0 mol% to 25.0 mol%. In some advantageous embodiments, the glass contains 2.0 mol% to 20.0 mol%, preferably 3.0 mol% to 15.0 mol%, also preferably 4.0 mol% to 12.0 mol% CaO. Some advantageous embodiments contain 15.0 mol% or less, preferably 12.0 mol% or less, 11.0 mol% or less, 10.0 mol% or less, or 8.0 mol% or less CaO. Some advantageous embodiments are CaO-free.

[0051] The SrO content is preferably in the range of 0 mol% to 7.0 mol% or 6.5 mol%. In some advantageous embodiments, the SrO content is in the range of 0 mol% or 1.0 mol% to 5.0 mol%, preferably 1.5 mol% to 4.0 mol%. In some advantageous embodiments, no SrO is present.

[0052] Preferably, the glass contains a total content of RO+RO in the range of 20.0 mol% to 40.0 mol%, preferably 25.0 mol% to 35.0 mol%, preferably 26.0 mol% to 33.0 mol%. Glasses with the above total contents of RO and RO exhibit favorable glass-forming properties. If the contents of RO and RO are too low, the glass has an unfavorably high melting temperature, and if the contents are too high, the crystallization tendency of the glass increases.

[0053] Optionally, the glass may contain ZnO. However, since ZnO is harmful to water and may affect the bath and crucible, the ZnO content is limited according to the invention to less than 5.0 mol%. In advantageous embodiments, the glass has a ZnO content of 0 to 5.0 mol%, or greater than 0 mol% to 4.5 mol%, preferably 0.5 mol% to 3.5 mol%, more preferably 0.7 mol% to 2.5 mol%, and particularly preferably 0.8 mol% to 2.0 mol%. Some advantageous variants are ZnO-free.

[0054] Optionally, the glass may contain Ln2O3, where 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%, and preferably less than 1.0 mol%. Preferably, the glass is Ln2O3-free.

[0055] Due to the low viscosity of the melt at the temperatures required for melt introduction, the addition of conventional refining agents is not necessary. Nevertheless, the addition of refining agents such as As2O3, Sb2O3, SO3, F and / or Cl can significantly reduce their content, for example to less than 0.1 mol%. Pure physical refining is also possible and advantageous. Optionally, the glass may be treated with the following refining agents in specified proportions in mol%: [Table 1] The compound may have one or more of the following components:

[0056] Sulfate (SO3) may be present in the glass in small proportions to stabilize higher oxidation states of polyvalent ions. If sulfate is present, this proportion is at least 0.01 mol%. The higher the sulfate proportion, the greater the risk of strong bubbling in the glass and the risk of platinum reaching the glass. Therefore, the sulfate proportion may advantageously be at most 0.5 mol%, preferably at most 0.1 mol%, preferably at most 0.05 mol%. Preferably, the glass is SO3-free.

[0057] In some embodiments, F can favorably affect the transmittance of the glass by stabilizing higher oxidation states in multivalent ions.

[0058] The glass may contain small amounts of hafnium (HfO2), preferably at most 0.2 mol%, preferably at most 0.1 mol%, or at most 0.05 mol%. In principle, hafnium is not actively added, but reaches the glass together with the component ZrO2 via the raw materials. When very pure ZrO2 raw materials are used, the glass is advantageously HfO2-free.

[0059] In an advantageous embodiment, the glass comprises the following components in mol %: [Table 2] It has.

[0060] In an advantageous embodiment, the glass comprises the following components in mol %: [Table 3] It has.

[0061] In an advantageous embodiment, the optical glass comprises the following components in mol %: [Table 4] It has.

[0062] In an advantageous embodiment, the optical glass comprises the following components in mol %: [Table 5] It has.

[0063] In an advantageous embodiment, the optical glass comprises the following components in mol %: [Table 6] It has.

[0064] In an advantageous embodiment, the optical glass comprises the following components in mol %: [Table 7] It has.

[0065] In advantageous embodiments, the glass consists of at least 95.0 mol %, in particular at least 98.0 mol %, or at least 99.0 mol % of the components described herein, in particular the components listed in the table above. In one embodiment, the glass consists essentially entirely of these components.

[0066] Preferably, the glass is substantially free of bismuth (Bi2O3) and / or lead (PbO). The addition of bismuth would disproportionately increase the density of the glass. Furthermore, bismuth ions are reduced to elemental bismuth even at relatively low temperatures in the range of 1000°C, thereby resulting in a strong gray coloration of the glass. PbO is likewise avoided due to its adverse effect on the low density. Furthermore, it is also counted as a toxic component.

[0067] Due to the high content of niobium and titanium, expensive components such as tantalum (Ta2O5) and / or tungsten (WO3) and / or germanium (GeO2) are not required in the glass, or are required only in small proportions, in order to obtain a glass with the desired high refractive index.

[0068] Preferably, the glass is free of phosphate (PO), since PO makes the melt significantly reducing and reduces transmittance by reducing TiO and / or NbO. Furthermore, a reducing melt can corrode platinum, thereby increasing its incorporation into the melt and resulting in increased coloration or scattering of the glass.

[0069] Optionally, the glass is substantially free of one or more components selected, based on their respective cations, from cadmium, gallium, germanium, thallium, coloring components (e.g., cobalt, vanadium, chromium, molybdenum, copper, nickel, etc.), and combinations thereof. Components such as iron, cerium, manganese, selenium, and / or tellurium may optionally be contained in the glass in small proportions and may reach the glass, for example, as impurities. In particular, iron, cerium, selenium, and tellurium, but also manganese, may function as redox partners. Advantageously, however, these components are not intentionally added to the glass, either individually or in combination.

[0070] In this specification, when a glass is said to be free of a component or not contain a particular component, this means that this component may be present in the glass at most as an impurity. This means that this component is not added in a significant amount. According to the present invention, an insignificant amount is an amount less than 100 ppm, preferably less than 50 ppm, and most preferably less than 10 ppm (m / m).

[0071] Preferably, the optical glass has a pure transmittance (τ ) 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. i (10 mm, 460 nm)).

[0072] Net transmittance or net transmittance can be measured using methods familiar to those skilled in the art, for example according to DIN 5036-1:1978. In this specification, the net transmittance information relates to a wavelength of 460 nm and a sample thickness of 10 mm. The "sample thickness" information does not mean that the glass has this thickness, but only indicates to which thickness the net transmittance data relates.

[0073] Unless otherwise stated or apparent to one of ordinary skill in the art, measurements described herein are made at 20° C. and atmospheric pressure of 101.3 kPa.

[0074] In a further aspect, the present invention provides a crystalline ... d , Abbe number v less than 32 d , and temperatures T below 1350 °C max and comprising at least SiO2, TiO2 and Nb2O5, less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3 and / or Yb2O3, and having a K2O content greater than 0 mol%.

[0075] The detailed description and preferred embodiments given above with respect to the glass according to the invention apply equally in this context.

[0076] In a further aspect, the present invention provides a crystalline ... d , Abbe number v less than 32 d , and temperatures T below 1350 °C max and comprising at least SiO2, TiO2 and Nb2O5, less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3 and / or Yb2O3, and having a K2O content greater than 0 mol% and a B2O3 content of 0.5 mol% or less, preferably being B2O3-free.

[0077] The detailed description and preferred embodiments given above with respect to the glass according to the invention apply equally in this context.

[0078] In a further aspect, the present invention provides a crystalline ... d , Abbe number v less than 32 d , and temperatures T below 1350 °C maxand comprising at least SiO2, TiO2 and Nb2O5, and comprising less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3 and / or Yb2O3, and the glass has a K2O content greater than 0 mol% and a molar ratio of B2O3 to SiO2 of at least 0.09.

[0079] The detailed description and preferred embodiments given above with respect to the glass according to the invention apply equally in this context.

[0080] In a further aspect, the present invention provides a crystalline ... d , Abbe number v less than 32 d , and temperatures T below 1350 °C max and comprising at least SiO2, TiO2 and Nb2O5, less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3 and / or Yb2O3, and the glass has a B2O3 content of 0.5 mol% or less, and is preferably B2O3-free.

[0081] The detailed description and preferred embodiments given above with respect to the glass according to the invention apply equally in this context.

[0082] In a further aspect, the present invention provides a crystalline ... d , Abbe number v less than 32 d , and temperatures T below 1350 °C max and comprising at least SiO2, TiO2 and Nb2O5, less than 30.0 mol% SiO2, less than 5.0 mol% ZnO and less than 5.0 mol% Ln2O3, where Ln2O3=Y2O3, La2O3, Gd2O3 and / or Yb2O3, and the glass has a molar ratio of B2O3 to SiO2 of at least 0.09.

[0083] The detailed description and preferred embodiments given above with respect to the glass according to the invention apply equally in this context.

[0084] In one aspect, the present invention relates to a glass article comprising or consisting of a glass according to the present invention. The glass article may have a variety of shapes. Optionally, the article is in the form of: glass substrates for components of optical systems, in particular in AR glasses, in particular as components of a stack of substrates; in particular wafers with a maximum diameter of 5.0 cm to 50.0 cm, or 0.7 cm to 50 cm, preferably 3 cm to 45 cm, or 5 cm to 40 cm; - lenses, in particular ball lenses, rod lenses, prisms or aspherical surfaces, and / or - Optical waveguides, especially fibers or plates It has.

[0085] In a further embodiment, the glass article according to the invention is a chemically hardened glass article, in particular a chemically hardened glass substrate, a chemically hardened wafer, and / or a chemically hardened lens, which will be obvious to those skilled in the art as glass articles comprising chemically hardenable optical glass according to the invention.

[0086] Within the scope of this disclosure, chemically hardenable glass is understood to mean glass that can be used in an ion exchange process. In such a process, alkali metal ions are exchanged in the surface layer of a glass article, such as a wafer. This is done so that a compressive stress zone is established in the surface layer from that point onward, which is achieved by exchanging ions with smaller radii for ions with larger radii. For this purpose, the glass article is immersed in a so-called ion exchange bath, such as a salt melt, which contains ions with larger ionic radii, in particular potassium and / or sodium ions, so that these ions migrate to the surface layer of the glass article. Conversely, ions with smaller ionic radii, in particular lithium and / or sodium ions, migrate from the surface layer of the glass article to the ion exchange bath.

[0087] This results in the formation of a compressive stress zone, which can be described by a characteristic of compressive stress, also called "compressive stress" or abbreviated "CS," and by the compressive stress depth, also called "Depth of Layer" or abbreviated "DoL." This compressive stress depth DoL is well known to those skilled in the art and, within the scope of this disclosure, refers to the depth at which the stress curve has a stress zero crossing.

[0088] Higher mechanical strength can be achieved with such chemically hardened glass articles.

[0089] Preferably, the production of the chemically hardened glass article comprises the following steps: a) providing the glass article described above; b) performing at least a first ion exchange; c) optionally carrying out a second ion exchange Includes:

[0090] Preferably, the first ion exchange is carried out at a temperature between 350°C and 500°C, preferably between 370°C and 450°C, particularly preferably between 380°C and 430°C, for a period of 0.5 to 24 hours, preferably between 1 and 5 hours, more preferably between 2 and 8 hours, and the exchange bath contains at least one potassium salt, in particular KNO3, and / or at least one sodium salt, in particular NaNO3.

[0091] In some advantageous embodiments, a second ion exchange is then carried out at a temperature between 350°C and 500°C, preferably between 370°C and 450°C, particularly preferably between 380°C and 430°C, for a period of 0.5 to 24 hours, preferably between 1 and 5 hours, more preferably between 2 and 8 hours, the exchange bath containing at least one potassium salt, in particular KNO3, and / or at least one sodium salt, in particular NaNO3.

[0092] In a further aspect, the invention relates to the use of the glasses or glass articles described herein in AR glasses, meta-optics, wafer-level optics, optical wafer applications, or classical optics. Alternatively or additionally, the glasses described herein or the glass articles described herein can be used as wafers, lenses, or optical waveguides.

[0093] The glass according to the invention can be melted from commercially available raw materials, for example, as described in the not yet published German patent application DE 10 2020120168 A1, where the glass can be melted in an apparatus.

[0094] Working Example: The compositions shown in Tables 1 to 6 below were melted and their properties were investigated. Tables 1 to 5 show examples according to the invention (Examples 1 to 30), and Table 6 shows comparative examples (Comparative Examples A and B). For some glasses, the pure transmittance was determined.

[0095] Composition and properties: [Table 8]

[0096] [Table 9]

[0097] [Table 10]

[0098] [Table 11]

[0099] [Table 12]

[0100] [Table 13]

[0101] The example glasses according to the invention have low density at high refractive index and a favorable product of Abbe number and density, and low T max Within the scope of the present invention, it has been found that the glasses according to the invention have a low tendency to crystallize, whereas comparative examples A and B have a high tendency to crystallize.

[0102] Although the present invention has been described based on preferred embodiments, the present invention is not limited thereto and can be modified in various ways.

Claims

1. Optical glass having a refractive index n greater than 1.95, preferably 2.05 or less ｄ , Abbe number v less than 32 ｄ , and a temperature T below 1350 ° C. ｍａｘ and at least SiO ２ , TiO ２ and Nb ２ O ５ and less than 30.0 mol% of SiO ２ , less than 5.0 mol% ZnO and less than 5.0 mol% Ln ２ O ３ Ln ２ O ３ = Y ２ O ３ , La ２ O ３ , Gd ２ O ３ and / or Yb ２ O ３ and the glass satisfies at least one of the following conditions: (i) K greater than 0 mol% ２ O content, (ii) 0.5 mol % or less of B ２ O ３ content, (iii) a B of at least 0.09 ２ O ３ Against SiO ２ Molar ratio of Meet the optical glass.

2. The glass has a molar ratio of 1.5 to 3.5 (TiO ２ + ZrO ２ +2 ＊ Nb ２ O ５ +2 ＊ Ta ２ O ５ +2 ＊ Al ２ O ３ +SiO ２ +B ２ O ３ ) / (R ２ O+RO+2 ＊ Ln ２ O ３ ) and R ２ O=Li ２ O, Na ２ O and / or K ２ O, RO = MgO, CaO, SrO and / or BaO, and Ln ２ O ３ = Y ２ O ３ , La ２ O ３ , Gd ２ O ３ and / or Yb ２ O ３ 2. The optical glass according to claim 1, wherein

3. The glass has a viscosity of 120 g / cm ３ less than 100 g / cm ３ less than 90 g / cm ３ less than, and preferably 50 g / cm ３ More than 55 g / cm ３ More than 60 g / cm ３ Ultra Abbe number v ｄ 3. The optical glass according to claim 1, wherein the product of the refractive index and the density ρ is ρ.

4. 4. The optical glass according to claim 1, wherein the glass contains 3.5 mol % to 15.0 mol %, preferably 4.0 mol % to 13.0 mol % of BaO.

5. The glass has a total content of BaO, Nb of at least 40.0 mol%, preferably at least 43.0 mol%, and / or not more than 65.0 mol%, preferably not more than 62.0 mol%. ２ O ５ and TiO ２ 5. The optical glass according to claim 1, wherein

6. The glass contains a total content of R of 2.0 mol % to 25.0 mol %, preferably 4.0 mol % to 23.0 mol %. ２ O=Li ２ O, Na ２ O and / or K ２ O is R ２ The optical glass according to claim 1 , further comprising O.

7. 7. The optical glass according to claim 1, wherein the glass has a total content of RO, where RO=MgO, CaO, SrO and / or BaO, from 6.0 mol % to 30.0 mol %, and / or a total content of MgO, CaO and SrO from 2.0 mol % to 20.0 mol %.

8. The glass has a total content of RO+R of 20.0 mol % to 40.0 mol %, preferably 25.0 mol % to 35 mol %. ２ The optical glass according to claim 1 , further comprising O.

9. The glass contains 1.5 mol % to 5.5 mol %, preferably 5.0 mol % or less of ZrO ２ 9. The optical glass according to claim 1, comprising:

10. The glass contains the following components in mol %: 【Table 1】 The optical glass according to any one of claims 1 to 9, comprising:

11. The glass contains the following components in mol %: 【Table 2】 The optical glass according to claim 1 , comprising:

12. The glass contains the following components in mol %: 【Table 3】 The optical glass according to claim 1 , comprising:

13. 13. The optical glass according to claim 1, wherein the glass has a net transmittance of at least 80%, preferably at least 85%, more preferably at least 90%, and particularly preferably at least 93%, measured at a wavelength of 460 nm and a sample thickness of 10 mm.

14. The following forms: glass substrates for components of optical systems, in particular in AR glasses, in particular as components of a stack of substrates; wafers with a maximum diameter of, in particular, 5.0 cm to 50.0 cm, or 0.7 cm to 50 cm, preferably 3 cm to 45 cm, or 5 cm to 40 cm; lenses, in particular ball lenses, rod lenses, prisms or aspherical surfaces, and / or - optical waveguides, in particular fibres or plates; A glass article comprising the optical glass according to at least one of claims 1 to 13.

15. 15. Use of the optical glass or glass article according to at least one of claims 1 to 14 in AR glasses, meta-optics, wafer-level optics, optical wafer applications or classical optics and / or as a wafer, lens or optical waveguide.

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