Optical glass, method for producing the same, and optical element

Abstract

This invention provides an optical glass, a method for preparing the same, and an optical element thereof. The optical glass comprises SiO2, B2O3, La2O3, Gd2O3, TiO2, Nb2O5, and ZrO2; and further comprises one or more of Si3N4, BN, and Li3N; and, based on the total mass of anions as 100%, O 2‑ The content is 79-99.5%, SO4 2‑ With N 3‑ The total content of the components is 0.5-21%; the refractive index of the optical glass is 2.04-2.06, and the Abbe number is 25-30. The optical glass of this invention has excellent internal quality, good transmittance, high hardness, high transition temperature, and relatively low liquidus temperature, thereby improving the devitrification resistance (Tg / Lt) and giving the glass good crystallization properties. It is an ultra-high refractive index, low dispersion optical glass that can shorten the lens length and improve image quality.

Description

TECHNICAL FIELD

[0001] The present application relates to an optical glass, a preparation method thereof and an optical element, in particular to a special high refractive low dispersion optical glass, a glass preform and an optical element, and belongs to the technical field of inorganic non-metallic new materials. BACKGROUND

[0002] For the special high refractive optical glass, the refractive index, the Abbe number and the transmittance are the core optical properties, and the crystallization performance of the glass is the key performance affecting the glass preparation process. The refractive index and the Abbe number determine the basic function of the glass. The optical glass with a refractive index of 2.04-2.06 and an Abbe number of 25-30 belongs to the special high refractive low dispersion optical glass. The application of this kind of high-performance optical glass in the optical system can effectively shorten the length of the lens and improve the imaging quality.

[0003] In recent years, the digitalization and high-fineness of the equipment using optical systems have rapidly developed. In the field of various optical equipment such as photographic equipment (digital cameras, video cameras, etc.), image reproducing (projecting) equipment (projectors, projection televisions, etc.), the demand for reducing the number of optical elements (lenses, prisms, etc.) used in the optical system and making the optical system as a whole lightweight and small is strong. In the optical glass for manufacturing optical elements, the demand for special high refractive, low dispersion, high-strength optical glass having a refractive index (n d ) of 2.04-2.06 and an Abbe number (υ d ) of 25-30, which can achieve the miniaturization of the optical system as a whole, is high.

[0004] The optical glass described in patent document Japanese Patent Application Publication No. 2009-203155 contains a large amount of a component (for example, Ta2O5) having a high price among various glass components. However, in order to achieve the low cost of the optical element formed of the special high refractive, low dispersion glass, it is desirable to reduce the proportion of the high-priced glass component in the glass composition of the optical glass.

[0005] Patent document CN110128004A discloses an oxide optical glass with an Abbe number υ d of 23-35 and a refractive index n d satisfying the following nd≥2.205-(0.0062×υ d ), wherein Si 4+ , B 3+ , La 3+ , Ti 4+ , Nb 5+ and Zr 4+ are essential components and are included in the form of cation %. 4+ 3+ ​; 10-50% La 3+ (where La) 3+ Gd 3+ Y 3+ and Yb 3+ The total of Ti is less than 70%; and the total of Ti is 22% to 55%. 4+ 、Nb 5+ Ta 5+ and W 6+ , among which, Ti 4+ The content is below 22%, Si 4+ The content relative to Si 4+ and B 3+ The total content of cation ratio [Si] 4+ / (Si 4+ +B 3+ [ ] is below 0.40, Ti 4+ The content relative to B 3+ The content of cation ratio (Ti 4+ / B 3+ The value is above 0.85. This patent belongs to oxide glass, which results in poor glass transmittance, mechanical properties, and crystallization properties.

[0006] Patent document CN101613184A discloses a low-dispersion oxide glass with a refractive index of 1.92–2.2, an Abbe number of 25–45, and a glass transition temperature (Tg) higher than 630℃, and an extremely high refractive index. When expressed as a cation-based glass, it contains Si. 4+ 3-20%, B 3+ 18-35%, Li + Na + and K + The total amount is less than 5%, Mg 2+ Ca 2+ and Sr 2+ The total amount is less than 5%, Ba 2+ 0-8%, Zn 2+ 0.1-10%, La 3+ 18-40%, Gd 3+ : 1~10%, Y 3+ 0-7%, Zr 4+ 2-8%, Ti 4+ 8-22%, Nb 5 + : 1-14%, excluding Te. The patented anion contains O 2- If the content is greater than 99.5%, the glass has poor transmittance, mechanical properties, and crystallization properties.

[0007] Patent document CN103351100A discloses a refractive index nd 1.92-2.2, Abbe number υ d 25-45, optical glass with glass transition temperature of 660℃ or more, the first glass includes Ti 4+ 0.1-22%, Nb 5+ 0-20%, etc., the patent is an oxide glass, the glass has poor transmission performance, mechanical properties, crystallization performance, etc.

[0008] Patent document CN104136388A discloses a refractive index n d 1.95-2.50 and Abbe number υ d 18-40, wherein the Si 4+ , B 3+ , La 3+ , Ti 4+ , Nb 5+ , and Gd 3+ , Y 3+ and Yb 3+ at least one of the essential components, expressed in cation % contains a total of 23-70% of Ti 4+ , Nb 5+ , Ta 5+ and W 6+ , the patent is an oxide glass, the glass has poor transmission performance, mechanical properties, crystallization performance, etc.

[0009] Patent document CN101289276A provides a high refractive high dispersion optical glass with refractive index ≥1.95 and Abbe number ≤35, its composition is: B2O3: 6-12%, SiO2: 2-8%, GeO2: 0-6%, La2O3: 20-55%, Gd2O3: 0-12%, TiO2: 10-18, Nb2O5: 5-20%, WO3: 0-8%, ZrO2: 1-10%, Ta2O5: 0-10%, Lu2O3: 3: 0-8%, Li2O: 0-1%, BaO: 0-15%, the patent cannot better eliminate bubbles and obtain higher transmission performance and color degree.

[0010] The glass provided in the above disclosed patent document has the following two problems, on the one hand, its glass composition cannot completely meet the requirements of the present invention with refractive index 2.04-2.06 and Abbe number 25-30; on the other hand, under the premise of meeting the requirements of refractive index 2.04-2.06 and Abbe number 25-30, its color degree is higher, the transmission performance is poorer, or the crystallization performance is obviously deteriorated, etc., which is not conducive to the manufacturing process requirements of optical glass. SUMMARY

[0011] Problems to be solved

[0012] As an optical glass having a very high refractive index (n d ) of 2.04-2.06 and an Abbe number (υ d ) of 25-30, the known optical glass has a relatively large specific gravity and a low transmittance. And, for the development trend of lightening of optical elements and optical devices, it is also required to achieve a smaller specific gravity, a better crystallization performance and a higher transmittance.

[0013] In view of the above technical problems, the present application first provides an optical glass having a refractive index (nd) of 2.04-2.06, an Abbe number (υ d ) of 25-30, a transmittance, a good crystallization performance and a lightening of optical elements and optical devices.

[0014] Further, the present application also provides a preparation method of the optical glass, which is simple and easy to operate and the raw materials are easy to obtain.

[0015] Further, the present application also provides an optical element made of the optical glass by molding.

[0016] Solution for solving the problem

[0017] The present application provides an optical glass, which comprises SiO2, B2O3, La2O3, Gd2O3, TiO2, Nb2O5 and ZrO2; and,

[0018] The optical glass further comprises one or more than two combinations of Si3N4, BN and Li3N; and,

[0019] The total mass of O 2- is 79-99.5%, the total mass of SO4 2- is 0.5-21%, and the total mass of N 3- is 0.5-21%.

[0020] The optical glass has a refractive index of 2.04-2.06 and an Abbe number of 25-30.

[0021] According to the optical glass of the present application, the optical glass comprises the following components, with the total mass of the optical glass being 100%:

[0022] SiO2: 5-10%, preferably 6-9%;

[0023] B2O3: 4-6.5%, preferably 4.5-6%;

[0024] La2O3: 35-58%, preferably 40-50%;

[0025] Gd2O3: 5 to 15%, preferably 8 to 15%;

[0026] Y2O3: 0 to 5%, preferably 0 to 4%;

[0027] Nb2O5: 5 to 15%, preferably 6 to 13%;

[0028] TiO2: 10 to 20%, preferably 12 to 18%;

[0029] ZnO: 0 to 5%, preferably 0 to 3%;

[0030] ZrO2: 3 to 8%, preferably 4 to 7%;

[0031] Si3N4: 0 to 5%, preferably 0.1 to 4.5%;

[0032] BN: 0 to 5%;

[0033] Li2SO4: 0 to 1%, preferably 0 to 0.8%;

[0034] ZnSO4: 0 to 2%, preferably 0 to 1.5%;

[0035] Li3N: 0 to 3%, preferably 0.1 to 2.5%;

[0036] Sb2O3: 0 to 0.05%, preferably 0 to 0.03%; and,

[0037] Si3N4, BN, Li3N are not always 0.

[0038] The optical glass according to the present application, wherein the sum of the contents of SiO2and B2O3∑(SiO2+B2O3) is 10 to 15% in mass%; and / or,

[0039] The ratio of the contents of SiO2and B2O3SiO2 / B2O3is 1.0 to 2.0.

[0040] The optical glass according to the present application, wherein the sum of the contents of SiO2and B2O3∑(SiO2+B2O3) is 10 to 15% in mass%; and / or,

[0041] The ratio of the contents of SiO2and B2O3SiO2 / B2O3is 1.0 to 2.0.

[0042] The ratio of the sum of the contents of TiO2and Nb2O5∑(TiO2+Nb2O5) to the sum of the contents of SiO2and B2O3∑(SiO2+B2O3) is 1.50 to 3.0.

[0043] The optical glass according to the present application, wherein, in terms of mass percentage,

[0044] The sum of the contents of TiO2 and Nb2O5, ∑(TiO2+Nb2O5), is 18 to 30%; and / or,

[0045] The ratio of the content of Nb2O5 to the content of TiO2, Nb2O5 / TiO2, is 0.35 to 2.5; and / or,

[0046] The ratio of the content of Nb2O5 to the sum of the contents of Nb2O5 and TiO2, Nb2O5 / (TiO2+Nb2O5), is 0.25 to 0.92.

[0047] The optical glass according to the present application, wherein, in terms of mass percentage,

[0048] The sum of the contents of La2O3, Y2O3, and Gd2O3, ∑(La2O3+Y2O3+Gd2O3), is 50 to 65%; and / or,

[0049] The ratio of the content of Gd2O3 to the sum of the contents of La2O3, TiO2, and ZrO2, Gd2O3 / ∑(La2O3+TiO2+ZrO2), is 0.1 to 0.3; and / or,

[0050] The ratio of the sum of the contents of Gd2O3 and La2O3 to the content of Nb2O5, ∑(Gd2O3+La2O3) / Nb2O5, is 3.5 to 9.5; and / or

[0051] The ratio of the content of Gd2O3 to the sum of the contents of La2O3, Y2O3, and Gd2O3, Gd2O3 / ∑(La2O3+Y2O3+Gd2O3), is 0.1 to 0.3; and / or,

[0052] The ratio of the content of La2O3 to the sum of the contents of Y2O3, Gd2O3, and ZrO2, La2O3 / ∑(Y2O3+Gd2O3+ZrO2), is 1.5 to 4.5.

[0053] The optical glass according to the present application, wherein, in terms of the total mass of anions being 100%, the content of SO4 2- is 0.1 to 5.5%, the content of N 3- is 0.4 to 15.5%; and / or,

[0054] The ratio of the content of N 3- to the sum of the contents of SO4 2- and N 3- , N 3- / ∑(N 3- +SO4 2- ), is 0.25 to 0.98.

[0055] According to the optical glass of the present application, wherein the internal transmission color degree of the optical glass λτ 80 / λ τ5 , λτ 80 At 422nm or below, λτ5 is at 362nm or below;

[0056] The transition temperature of the optical glass is at 750℃ or below, and the sag temperature is at 790℃ or below;

[0057] The specific gravity of the optical glass ρ is at 5.37 or below;

[0058] The hardness HK of the glass of the optical glass is at 690×10 7 Pa or above.

[0059] The present application also provides a preparation method of the optical glass according to the present application, characterized in that the preparation method comprises weighing and mixing the component raw materials of the optical glass according to the proportion, then smelting, and then forming the optical glass by using a forming mold.

[0060] The present application also provides an optical element comprising the optical glass according to the present application.

[0061] Effects of the present application

[0062] The optical glass of the present application has excellent internal quality, good transmittance, high hardness, high transition temperature, and relatively low liquidus temperature, thereby improving the resistance to devitrification Tg / Lt, and the glass has good crystallization performance. It is a special high refractive index low dispersion optical glass, which can shorten the length of the lens and improve the imaging quality.

[0063] The preparation method of the optical glass of the present application is simple and easy to operate, other raw materials are easy to obtain, the cost of the formula is relatively low, and it is suitable for mass production. DETAILED DESCRIPTION

[0064] Various exemplary embodiments, features, and aspects of the present application will be described in detail below. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations.

[0065] In addition, in order to better illustrate the present application, numerous specific details are given in the following detailed description. Those skilled in the art will understand that the present application can be implemented without certain specific details. In some other examples, methods, means, apparatuses and steps that are well known to those skilled in the art are not described in detail, in order to highlight the main idea of the present application.

[0066] The units used in the present specification are international standard units unless otherwise specified, and the numerical values, numerical ranges appearing in the present application should be understood to include inevitable systematic errors in industrial production.

[0067] In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.

[0068] In the present specification, the "some specific / preferred embodiments", "other specific / preferred embodiments", "embodiments", and the like refer to the specific elements (for example, features, structures, properties, and / or characteristics) described in relation to the embodiments are included in at least one embodiment described herein, and can be present in other embodiments or can not be present in other embodiments. In addition, it should be understood that the elements can be combined in various embodiments in any suitable manner.

[0069] In the present specification, the numerical range represented by "numerical value A to numerical value B" means a range including the end point values A, B.

[0070] In the present specification, when "room temperature" is used, the temperature can be 10-40°C.

[0071] In the present specification, the content of each component is represented as a percentage content of the component with respect to the total mass of all components unless otherwise specified. In the optical glass produced in the present application, each component having the above content is selected for the following reasons.

[0072] The present application provides an optical glass, wherein the optical glass comprises SiO2, B2O3, La2O3, Gd2O3, TiO2, Nb2O5, ZrO2; and the optical glass further comprises one or a combination of two or more of Si3N4, BN, and Li3N; and, with respect to the total mass of anions being 100%, the content of O 2- is 79-99.5%, the content of SO4 2- and N 3- is 0.5-21%; the refractive index of the optical glass is 2.04-2.06, and the Abbe number is 25-30.

[0073] The present application can reduce the difficulty of defoaming and improve the glass transmittance by introducing specific anions, O 2- , SO4 2- , and N 3-

[0074] ​The optical glass of the present invention has a refractive index of 2.04 to 2.06. This exceptionally high refractive index allows for a large amount of light refraction even when the optical element is made thinner. Furthermore, the low dispersion of the present invention reduces focal point shift (chromatic aberration) caused by the wavelength of light when used as a single lens. Therefore, when combined with an optical element having high dispersion (low Abbe number) to construct an optical system, for example, aberrations of the entire optical system can be reduced, and high imaging characteristics can be achieved. Thus, the optical glass of the present invention is effective in optical design, particularly in constructing optical systems, enabling not only high imaging characteristics but also miniaturization of the optical system, thereby increasing the freedom of optical design.

[0075] In some specific implementation schemes, SO4 is calculated based on a total mass of 100% of the anions. 2- The content is 0.1%–5.5%, N 3- The content is 0.4–15.5; when SO4 2- The content is 0.1%–5.5%, N 3- When the content is between 0.4% and 15.5%, it is easier to reduce the difficulty of defoaming and at the same time improve the glass transmittance.

[0076] Furthermore, in some other specific implementation schemes, N 3- With SO4 2- and N 3- The ratio N of the sum of the contents of 3- / ∑(N 3- +SO4 2- The value is between 0.25 and 0.98. If N... 3- / ∑(N 3- +SO4 2- If N is too low, it will not achieve the effect of improving transmittance; if N... 3- / ∑(N 3- +SO4 2- If the temperature is too high, the melting process will become more difficult, and the elimination of bubbles will be affected to some extent.

[0077] Specifically, in this invention, the optical glass, based on its total mass of 100%, contains the following components:

[0078] SiO2: 5-10%, preferably 6-9%;

[0079] B2O3: 4–6.5%, preferably 4.5–6%;

[0080] La2O3: 35-58%, preferably 40-50%;

[0081] Gd2O3: 5-15%, preferably 8-15%;

[0082] Y2O3: 0-5%, preferably 0-4%;

[0083] Nb2O5: 5-15%, preferably 6-13%;

[0084] TiO2: 10-20%, preferably 12-18%;

[0085] ZnO: 0-5%, preferably 0-3%;

[0086] ZrO2: 3-8%, preferably 4-7%;

[0087] Si3N4: 0-5%, preferably 0.1-4.5%;

[0088] BN: 0-5%;

[0089] Li2SO4: 0-1%, preferably 0-0.8%;

[0090] ZnSO4: 0-2%, preferably 0-1.5%;

[0091] Li3N: 0-3%, preferably 0.1-2.5%;

[0092] Sb2O3: 0-0.05%, preferably 0-0.03%; and,

[0093] The content of Si3N4, BN and Li3N is not zero.

[0094] In the present application, the SiO2 component is a necessary component for forming the glass-forming oxide, which forms a three-dimensional network of the glass as a network former with silicon oxygen tetrahedron [SiO4], strengthens the loose [BO3] network, and strengthens the glass skeleton network. At the same time, the dense [SiO4] network can isolate La 3+ , Nb 5+ and other easily crystallized cations, and improve the anti-crystallization performance of the glass. Therefore, the appropriate amount of SiO2 component is used, on the one hand, to easily obtain stable glass; on the other hand, to improve the viscosity of the molten glass and to reduce the coloring of the glass, which plays an important role in maintaining the forming viscosity of the molten glass and improving the chemical durability. Therefore, the appropriate amount of SiO2 can improve the chemical stability of the glass, maintain the crystallization performance of the glass, and increase the forming viscosity of the glass, which is beneficial to the forming of the glass preform.

[0095] In the present application, in order to effectively achieve the above-mentioned effects, the content of SiO2may be 5% or more, preferably 6% or more, based on the total mass of the optical glass being 100%. On the other hand, in order to obtain the required very high refractive index while suppressing the increase in liquidus temperature and glass transition temperature, the content of SiO2may be 10% or less, based on the total mass of the optical glass being 100%, otherwise the glass transition temperature (Tg) and the melting temperature of the glass prepared will be too high, and the decrease in refractive index will be suppressed. In addition, the content of SiO2is preferably 9% or less, and more preferably the upper limit is 8%, from the required high refractive index and Abbe number requirements, the maintenance of the glass melting property, and the improvement of the devitrification resistance.

[0096] B2O3is also a necessary component as a glass-forming oxide. As a glass network former, B2O3forms a network skeleton in the form of a boron-oxygen triangle [BO3] sheet / lamellar network in the glass, can reduce the high-temperature viscosity of the glass, accelerate the melting of the glass, is a necessary component for reducing the transition temperature, obtaining low dispersion, and stable glass, has the effects of improving the glass melting property, reducing the liquidus temperature, and achieving low dispersion, and also has the effects of improving the devitrification resistance of the glass, reducing the glass transition temperature, and reducing the specific gravity. From the viewpoint of glass stability, by controlling the content of B2O3, the stability of the glass is improved, the devitrification resistance is improved, and the Abbe number of the glass is improved. Therefore, the content of the B2O3component can be 4% or more, preferably 4.5% or more, based on the total mass of the optical glass being 100%. On the other hand, from the viewpoint of maintaining chemical durability and the like while obtaining the required refractive index, the content of B2O3may be 6.5% or less, preferably 6% or less, based on the total mass of the optical glass being 100%, so that a larger refractive index can be easily obtained, and the deterioration of the chemical durability can be suppressed.

[0097] In the present application, when the sum of the contents of SiO2and B2O3∑(SiO2+B2O3) is too low, the stability of the glass will deteriorate, and the liquidus temperature will increase, and when the proportion of the sum of the contents of SiO2and B2O3∑(SiO2+B2O3) is too high, it will be difficult to achieve the required refractive index. By controlling the sum of the contents of SiO2and B2O3∑(SiO2+B2O3) to be 10-15%, preferably 11-14%, the requirements for the refractive index and the Abbe number can be further satisfied.

[0098] The ratio of SiO2to B2O3, SiO2 / B2O3, can not only increase the melting property and the stability of the raw material, but also optimize the network structure of the glass, so that the weather resistance and the devitrification resistance of the glass are more excellent. Therefore, in the present application, the ratio of SiO2to B2O3, SiO2 / B2O3, can be 1.0-2.0, preferably 1.2-1.8, and more preferably 1.2-1.6, in terms of mass percentage.

[0099] The La2O3 component is a necessary component which is excellent in the effect of maintaining the stability of the glass and the effect of high refractive index and low dispersion, and is also a component which plays a role in improving the chemical durability. In addition, since it is relatively inexpensive among rare earths, the material cost of the glass can be reduced. Therefore, in the present application, the content of La2O3may be 35-58%, preferably 40-50%, and more preferably 42-48%, based on the total mass of the optical glass. If the content of La2O3is too low, it is difficult to obtain the desired refractive index and Abbe number, and at the same time, the chemical durability and the mechanical strength of the glass can be improved by introducing La2O3of 35% or more; but when the content of La2O3is too high, the devitrification tendency of the glass increases and the liquidus temperature rises. Therefore, in addition, the La2O3component can be contained in the glass using, for example, La2O3, La(NO3)3, and La(CH3COO)3, or the like as a raw material, and the above-mentioned raw material can also be used to adjust the atmosphere during the production of the glass, thereby achieving the effects of improving the transmittance and the degree of coloration.

[0100] Gd2O3is a necessary component which has the same effect as La2O3, and it can increase the refractive index and reduce the dispersion of the glass, and also improve the chemical stability, and has the effect of improving the crystallization property of the glass, and increases the mechanical strength while appropriately increasing the refractive index. In particular, when the content of the Gd2O3component is too low, the glass separation can be suppressed, the glass forming property can be improved, and the glass can not easily devitrify during production. However, if it is introduced in excess, especially when the content is too high, the stability of the glass decreases, and the liquidus temperature and the transition temperature rise, and therefore the content of the Gd2O3component can be 5-15%, and preferably 8-15%.

[0101] Y2O3is an optional component of the present application. Y2O3is a high refractive index and low dispersion oxide, and can be added to the glass instead of part of Gd2O3and Nb2O5to adjust the refractive index, improve the anti-crystallization property, and save the production cost. Therefore, in the present application, the melting property, the devitrification resistance of the glass can be improved by introducing Y2O3, and the liquidus temperature and the specific gravity of the glass can also be reduced; but when the content is too high, the stability and the devitrification resistance of the glass decrease. Therefore, the content of Y2O3may be 0-5%, preferably 0-4%, and more preferably 0.5-3%, based on the total mass of the optical glass.

[0102] Further, when the content of Y2O3 is greater than 0%, it is possible to maintain a high refractive index and a high Abbe number, and to suppress the material cost of the glass, and it is possible to reduce the specific gravity of the glass. Therefore, the content of the Y2O3 component is preferably greater than 0%, and more preferably 0.5% or greater. On the other hand, by making the content of the Y2O3 component 5.0% or less, it is possible to suppress a decrease in the refractive index of the glass, and to improve the stability of the glass. In addition, it is possible to suppress a decrease in the melting property of the glass raw material. Therefore, the content of the Y2O3 component is preferably 5.0% or less, more preferably 4.0% or less, and still more preferably 3.0% or less.

[0103] Since La2O3, Y2O3, and Gd2O3 are all high refractive index and low dispersion components, they also function to improve chemical durability. In order to reduce devitrification of the glass during production, the sum of the contents of La2O3, Y2O3, and Gd2O3, ∑(La2O3+Y2O3+Gd2O3), is 50 to 65% by mass, and is preferably 52 to 63%. However, when ∑(La2O3+Y2O3+Gd2O3) is too high, the stability of the glass decreases, and the liquidus temperature increases. However, when ∑(La2O3+Y2O3+Gd2O3) is too low, the glass cannot achieve the desired refractive index, Abbe number. In the optical glass of the present application, even if a large amount of rare earth elements are contained, the partial dispersion ratio is not easily decreased, and thus it is easy to obtain a desired high partial dispersion ratio, high refractive index, and Abbe number.

[0104] In the present application, the ratio of the content of Gd2O3 to the sum of the contents of La2O3, Y2O3, and Gd2O3, Gd2O3 / ∑(La2O3+Y2O3+Gd2O3), directly affects the crystallization properties of the glass. If Gd2O3 / ∑(La2O3+Y2O3+Gd2O3) is too small, the glass easily crystallizes, and the goal of improving the crystallization properties is not achieved; and if Gd2O3 / ∑(La2O3+Y2O3+Gd2O3) is too high, the liquidus temperature Lt sharply increases, and the liquidus temperature Lt of the glass increases. Substitution of Y2O3, La2O3 with Gd2O3 reduces the tendency of the glass to crystallize, and the main reason for this is that the presence of Gd2O3, Y2O3, and La2O3 together weakens the accumulation of La2O3, and is advantageous for the formation of the glass, and increases the resistance to ionic rearrangement upon cooling of the melt. The present inventors have found that when Gd2O3 / ∑(La2O3+Y2O3+Gd2O3) is 0.1 to 0.30, and is preferably 0.20 to 0.27, it is possible to obtain a desired glass having good crystallization properties.

[0105] TiO2 is a high refractive index dispersive oxide, which can increase the refractive index and dispersion of the glass, and is a necessary component of the present application. Adding appropriate TiO2 into the glass can enter the glass network and become a part of the network, which can improve the chemical stability and anti-crystallization performance of the glass. TiO2 can also reduce the use amount of high-priced Nb2O5 and Gd2O3, thereby reducing the cost of raw materials. Therefore, TiO2 can increase the refractive index of the glass, reduce the liquidus temperature of the glass, improve the stability of the glass, reduce the specific gravity of the glass, and reduce the material cost of the glass. Therefore, the content of TiO2 is 10.0% or more, preferably 12.0% or more, and more preferably 14.0% or more, based on the total mass of the optical glass. On the other hand, by limiting the content of the TiO2 component to 20.0% or less, the devitrification caused by excessive TiO2 component content can be further reduced, the transmittance of the glass to visible light (especially visible light with a wavelength of 500 nm or less) can be inhibited, and the decrease in the Abbe number can be inhibited. Therefore, the content of TiO2 can be 20.0% or less, preferably 18.0% or less, based on the total mass of the optical glass.

[0106] Since TiO2 in the glass causes severe glass coloring, in order to obtain the required transmittance of the glass, the ratio of the sum of the contents of SiO2 and B2O3 to TiO2, ∑(SiO2+B2O3) / TiO2, is limited. If ∑(SiO2+B2O3) / TiO2 is too low, the glass will be severely colored, and the required transmittance and coloration degree cannot be obtained. If ∑(SiO2+B2O3) / TiO2 is too high, the refractive index of the glass will decrease, and the requirement for ultra-high refractive index cannot be met. Therefore, the ratio of the sum of the contents of SiO2 and B2O3 to TiO2, (SiO2+B2O3) / TiO2, can be 0.5 to 1.3 in mass percent.

[0107] Nb2O5 is a high refractive index and high dispersion oxide, which can increase the refractive index and chemical stability of the glass. If the content is too low, the refractive index and Abbe number of the present application cannot be achieved. If the content is too high, the anti-crystallization performance of the glass will decrease sharply. Therefore, the content of Nb2O5 can be 5% to 15%, preferably 6% to 13%, and further preferably 7% to 12%.

[0108] TiO2 and Nb2O5 play an important role in improving the refractive index and the resistance to devitrification, inhibiting the rise of liquidus temperature, and improving the chemical durability. If the sum of the contents of TiO2 and Nb2O5, ∑(TiO2+Nb2O5), is too low, the above effects are difficult to achieve; if the sum of the contents of TiO2 and Nb2O5, ∑(TiO2+Nb2O5), is too high, the resistance to devitrification will be poor, and the liquidus temperature will rise. In addition, the dispersion will be high, and the glass will be colored. Therefore, in order to ensure that the desired refractive index, Abbe number and stability are achieved, and the cost of raw materials is relatively low, the ∑(TiO2+Nb2O5) can be 18-30%, preferably 20-28% by mass.

[0109] In order to balance the transmittance and crystallization performance of the glass, the ratio of Nb2O5 / TiO2 or Nb2O5 / (TiO2+Nb2O5) needs to be strictly controlled. If the ratio is too high, the crystallization performance of the glass will deteriorate sharply, and the glass will easily crystallize during forming and pressing, increasing the difficulty of product control and even affecting the product quality; if the ratio is too low, the transmittance of the glass will deteriorate significantly, and the desired transmittance performance cannot be achieved. Therefore, the ratio of Nb2O5 / TiO2 or Nb2O5 / (TiO2+Nb2O5) can be controlled to be 0.35-2.5 and 0.25-0.92, respectively.

[0110] The WO3 component is an optional component. When the content of WO3 is greater than 0%, the refractive index of the glass can be improved, but the glass will be colored, thereby reducing the transmittance of the glass in the visible light band. Therefore, the glass of the present application preferably does not contain WO3.

[0111] ZrO2 is a relatively high-refractive-index low-dispersion oxide. When added to the glass, it can adjust the refractive index and dispersion of the glass, and by coexisting with TiO2, it can improve the resistance to devitrification and inhibit the rise of liquidus temperature, thereby improving the chemical stability and anti-crystallization performance of the glass. In order to achieve the above effects, the content of the ZrO2 component can be greater than 3%, which can improve the resistance to devitrification of the glass. The content of the ZrO2 component can be less than 8%, which can inhibit the decrease of the Abbe number of the glass, and avoid the melting of the glass at high temperatures during glass manufacturing, thereby reducing the energy loss during glass manufacturing. If the content is too high, the melting temperature of the glass will increase significantly, the transmittance will decrease, and the risk of crystallization and stone formation of the glass will also increase. Therefore, the content of ZrO2 can be 3-8%, preferably 4-7%, based on the total mass of the optical glass.

[0112] In order to increase the refractive index while maintaining the stability of the glass, to ensure the desired refractive index and Abbe number, as preferred, the ratio of the sum of the contents of TiO2 and Nb2O5 to the sum of the contents of SiO2 and B2O3, ∑(TiO2+Nb2O5) / ∑(SiO2+B2O3), is 1.50-3.0. In particular, by making ∑(TiO2+Nb2O5) / ∑(SiO2+B2O3) be 1.50 or more, preferably 2.0 or more, and more preferably 2.2 or more, the glass with the desired very high refractive index can be easily obtained. On the other hand, by making ∑(TiO2+Nb2O5) / ∑(SiO2+B2O3) be 3.0 or less, preferably 2.5 or less, and more preferably 2.4 or less, the stability of the glass can be improved, and the decrease in Abbe number can be inhibited.

[0113] Further, it has been found through experimental research that Gd2O3 can slightly adjust the crystallization performance of the glass, and has a great effect on the improvement of the crystallization of the glass. However, when the ratio of the content of Gd2O3 to the sum of the contents of La2O3, TiO2 and ZrO2, Gd2O3 / ∑(La2O3+TiO2+ZrO2), is too low, the crystallization performance of the glass cannot be effectively improved, the chemical stability of the glass is poor, and the light transmittance and hardness decrease; when the ratio of the content of Gd2O3 to the sum of the contents of La2O3, TiO2 and ZrO2, Gd2O3 / ∑(La2O3+TiO2+ZrO2), is too high, the crystallization of the glass can be effectively improved, but the glass-forming stability and anti-crystallization performance of the glass decrease. Therefore, in the present application, Gd2O3 / ∑(La2O3+TiO2+ZrO2) can be 0.10-0.30, and preferably 0.13-0.25.

[0114] Further, it has been found through experimental research that Gd2O3 can slightly adjust the crystallization performance of the glass, and has a great effect on the improvement of the crystallization of the glass. However, when the ratio of the content of Gd2O3 to the sum of the contents of La2O3, TiO2 and ZrO2, Gd2O3 / ∑(La2O3+TiO2+ZrO2), is too low, the crystallization performance of the glass cannot be effectively improved, the chemical stability of the glass is poor, and the light transmittance and hardness decrease; when the ratio of the content of Gd2O3 to the sum of the contents of La2O3, TiO2 and ZrO2, Gd2O3 / ∑(La2O3+TiO2+ZrO2), is too high, the crystallization of the glass can be effectively improved, but the glass-forming stability and anti-crystallization performance of the glass decrease. Therefore, in the present application, Gd2O3 / ∑(La2O3+TiO2+ZrO2) can be 0.10-0.30, and preferably 0.13-0.25.

[0115] Further, Y2O3, Gd2O3, ZrO2 all belong to high refractive index oxides, adding them into the glass can increase the refractive index of the glass, and more importantly, when Y2O3, Gd2O3, ZrO2 coexist with La2O3, the crystallization tendency of La2O3 can be greatly inhibited within a specific range. The present inventors have found that when the ratio of the content of La2O3 to the sum of the contents of Y2O3, Gd2O3 and ZrO2, i.e. La2O3 / ∑(Y2O3+Gd2O3+ZrO2) is 1.5-4.5, the anti-crystallization ability, including the internal anti-crystallization performance and the surface anti-crystallization performance, can be improved.

[0116] The ZnO component can reduce the refractive index and the glass stability, but it can improve the melting property and the fining property of the glass. Therefore, the ZnO component is an arbitrary component for reducing the liquidus temperature of the glass and improving the resistance to devitrification of the glass, and it can promote the melting of the glass raw materials during the melting of the glass, can reduce the high-temperature viscosity of the glass, and can positively affect the elimination of bubbles in the glass, and can also improve the chemical stability of the glass. The component can also reduce the glass transition temperature, and can improve the chemical durability and reduce the coloring of the glass, and it is an arbitrary component in the glass of the present application. In order to improve the melting property, the thermal stability, the formability, the machinability and other properties of the glass, the upper limit of the content of ZnO is preferably limited to 5% based on 100% of the total mass of the optical glass, the upper limit is preferably 3%, and the upper limit is more preferably 1%. Considering that ZnO can reduce the refractive index and the glass stability, the present application further preferably does not introduce ZnO.

[0117] The Si3N4 component is a covalently bonded substance, and although its melting point is very high, it has been found that Li2O in the alkali metal can be well melted with the glass melt, and the alkaline earth metal oxides and Y2O3, La2O3, ZrO2 and the like can also be well dissolved in the glass melt. However, Si3N4 can make the glass unstable. From the aspect of crystallization, TiO2 and ZrO2, which are the raw materials of the nucleating agent, will react with the glass melt in a reducing atmosphere and cannot be used as the nucleating agent, and ZrO2 can promote phase separation, and its nucleation ability increases with the increase of N. In addition, the addition of ZrO2 can produce tetragonal ZrO2 in the glass, which can further improve the resistance to crystallization and the mechanical properties of the glass. Therefore, the inventors need to add a certain amount of metal oxides, such as Li2O, MgO, Al2O3, Y2O3, La2O3, ZrO2 and the like, or a combination of two or more of them, to promote the formation of a eutectic melt. These oxides can react with Si3N4 and the oxide film SiO2 on the surface of Si3N4 to form a low-melting liquid phase.

[0118] The inventors discovered that when nitrogen (N) in Si3N4 is replaced by oxygen (O) from oxides to form a glassy phase, the mechanical strength and high-temperature properties of Si3N4 decrease significantly. This is relatively advantageous for the application of Si3N4 in glass manufacturing processes. One reason is that the nitrogen in Si3N4 is replaced by oxygen (O). 2- Ion substitution can form a small amount of oxynitrogen glass; secondly, if some of the O in the oxide glass... 2- The substitution of nitrogen (N) significantly improves the strength and other properties of oxide glasses. In silicate glasses, nitrogen replaces some oxygen in the SiO4 units, forming a network bridged by Si-N bonds. The Si-N bonds have shorter bond lengths, stronger covalent interactions than Si-O bonds, and higher coordination degrees. Introducing N into silicate glasses results in a more complete network structure by replacing oxygen (O) in the Si-O-Si structure, thus improving the glass's mechanical and chemical properties, including strength, elastic modulus, and hardness, as well as its transmittance. Specifically, in this invention, the Si3N4 content, based on 100% of the total mass of the optical glass, can be 0–5%, preferably 0.1–4.5%.

[0119] Boron nitride (BN) plays a similar role in glass as Si3N4, reducing non-bridging oxygen in the glass, increasing the stability of Si-N bonds, and improving the cross-linking degree of the glass network structure, thereby improving mechanical properties and transmittance. However, if the content is too high, the glass's solubility will decrease, bubbles and foreign matter will be difficult to eliminate, and Ti will exist in a colored low-valence state due to insufficient oxygen; if the content is too low, the purpose of improving the glass structure and transmittance will not be achieved. Therefore, in this invention, the BN content can be 0-5% based on the total mass of the optical glass (100%).

[0120] In lithium nitride (Li3N), nitrogen (N) can react with boron (B) to form nitrogen (BN). However, due to the large charge radius of lithium (Li), even in molten Li3N, Li still exerts a strong binding force on nitrogen (N), allowing even nitrogen bound by Li to acquire boron and form BN. This lowers the system energy and makes the system more stable. Furthermore, Li3N has a low melting point, which effectively reduces the glass melting temperature during melting, promoting the formation of a low-temperature eutectic and reducing the formation of foreign matter from materials that are difficult to melt. Specifically, in this invention, based on the total mass of the optical glass (100%), the Li3N content can be 0–3%, preferably 0.1–2.5%.

[0121] In the present application, the necessary nitride substance is introduced, which leads to the substitution of N for O in the network, which can be preferentially for bridging oxygen or non-bridging oxygen, forming Si-N bond, Al-N bond, B-N bond and P-N bond, etc. Because N is three-coordinated and O is two-coordinated, when N exists in the network structure, the cross-linking degree of the network can be increased, so that the optical glass of the present application has many properties of oxide glass, and more promotes the characteristics of oxygen-nitrogen glass. The refractive index, Young's modulus, viscosity, surface tension, glass transition temperature, softening temperature, electrical conductivity and transmittance of the glass increase with the increase of N content, while the thermal conductivity decreases with the increase of N content.

[0122] At the same time, the present application contains more variable valence element Ti, and Ti 3+ Compared with Pt, Ti is more easily oxidized, so in the case of insufficient oxygen atoms, Ti 3+ is oxidized to form Ti 4+ , and then Pt is oxidized to form platinum oxide. Therefore, in the case of appropriate addition amount of nitride such as Si3N4, BN or Li3N, the number of oxygen atoms in the glass liquid can only oxidize the residual low-valence Ti 3+ to form Ti 4+ , and there is no excess oxygen to combine with platinum element, thereby inhibiting the oxidation reaction of Pt and achieving the effect of improving transmittance; if the above nitride content is too low, the oxygen in the glass liquid will oxidize Ti 3+ to form Ti 4+ , and then oxidize Pt, resulting in too high content of platinum oxide melted into the glass. The melting of excessive platinum oxide also leads to the deepening of the color of the glass, thereby deteriorating the transmittance. If the above nitride content is too high, the melting property of the glass becomes poor, the melting temperature increases, bubble elimination is difficult, and foreign matter is easily produced.

[0123] The introduction of a small amount of ZnSO4 and Li2SO4 components in the glass can improve the melting property of the glass and reduce the glass transition temperature Tg. In addition, they are decomposed into SO3 2- under high temperature melting state. 2- SO3 2-ZnO exists as a network intermediate in the glass, and can improve the crystallization properties of the glass. Therefore, in order to ensure the defoaming effect and the crystallization properties, the amount of addition can be controlled to be less than 2%, preferably less than 1.5%, and more preferably less than 1%.

[0124] The Sb2O3 component is a component for defoaming molten glass, and a small amount of addition can also play a role in suppressing the decrease in light transmittance caused by the mixing of impurities such as Fe, and is an optional component in the optical glass of the present application. Note that the component that clarifies and defoams the glass is not limited to the above Sb2O3 component, and a fining agent, a defoaming agent, or a combination thereof known in the glass manufacturing field can be used. In particular, by making the content of the Sb2O3 component 0.05% or less, the Sb2O3 component can be made less likely to alloy with the melting equipment (particularly, a noble metal such as Pt). Otherwise, the glass can be colored. Therefore, the content of the Sb2O3 component is preferably 0.03% or less, and more preferably 0.02% or less, with respect to the total mass of the glass in terms of the oxide composition. The component that clarifies and defoams the glass is not limited to the above Sb2O3 component, and a fining agent, a defoaming agent, or a combination thereof known in the glass manufacturing field can be used.

[0125] The transition temperature of the optical glass of the present application is 750°C or less, and the sag temperature is 790°C or less; the hardness HK of the glass of the optical glass is 690 x 10 7 Therefore, the optical glass of the present application is suitable for being molded into an optical glass element, and is an optical glass that is excellent in internal quality and has good transmittance.

[0126] The specific gravity of the optical glass of the present application is 5.37 or less, based on the viewpoint of contributing to the lightening of optical elements and optical equipment. The optical glass of the above-described type is a special high refractive index glass, and when the glass reaches a special high refractive index, an increase in specific gravity generally tends to occur. However, an increase in specific gravity leads to an increase in the weight of the optical element. In relation to this, the optical glass of the above-described type has the above-described glass composition, and thus can be a special high refractive index glass while having a specific gravity of 5.37 or less. However, when the specific gravity is excessively decreased, a tendency for the stability of the glass to decrease and the liquidus temperature to increase tends to occur, and thus the specific gravity is preferably set to be 4.40 or more.

[0127] To ensure that the optical glass of the present invention has an exceptionally high refractive index and a low Abbe number, as well as high spectral transmittance, other components can be added as needed without compromising the properties of the glass of the present invention. In addition to one or more combinations of SiO2, B2O3, La2O3, Gd2O3, TiO2, Nb2O5, ZrO2, and Si3N4, BN, Li3N, it is preferable not to artificially introduce expensive components such as Ta2O5, WO3, GeO2, and Bi2O3 that increase the Abbe number, and preferably not to introduce raw materials such as Yb2O3 that absorb in the near-infrared band; it is also preferable not to artificially introduce coloring elements such as V, Cr, Mn, Fe, Co, Ni, Cu, Ag, and Mo, as even small amounts of these elements can color the glass and absorb light of specific wavelengths in the visible light region. Therefore, they are substantially absent, especially in optical glasses using wavelengths in the visible light region.

[0128] The internal light transmittance chromaticity λτ of the optical glass 80 / λ τ5 In, λ τ80 Below 422nm and with λτ5 below 362nm, the transmittance of the glass is relatively high. The optical glass provided by this invention should, due to the requirements of practical applications, maximize its transmittance, preferably with a light color. Therefore, this invention does not artificially introduce any other coloring elements besides the components mentioned above.

[0129] The transmittance of colorless optical glass in the visible light region is related to its transmittance. However, tinting degree does not take into account the effect of refractive index on glass surface reflection. Therefore, the transmittance performance of optical glass can be expressed using the λ corresponding to the internal tinting degree. τ80 Therefore, in this invention, λ is used to represent... τ80 The corresponding wavelength is below 422nm, preferably below 418nm, and more preferably below 410nm. Wherein, λ τ80 This refers to the wavelength at which the internal transmittance of light reaches 80% within the wavelength range of 280–700 nm. The internal transmittance is calculated by irradiating light onto a glass sample with parallel surfaces, polished to a thickness of 5.0 ± 0.1 mm or 15.0 mm ± 0.1 mm, from a perpendicular direction. Specifically, it is Iout / Iin, where the intensity of the light incident on the sample is Iin, and the intensity of the light transmitted through the sample is Iout. The spectral transmittance does not include light reflection loss from the sample surface. Polishing means smoothing the surface to a sufficiently small roughness relative to the wavelength range of the measurement region. As mentioned earlier, the spectral transmittance is measured within the wavelength range of 280–700 nm, typically when the wavelength ranges from λ… τ5The light transmittance increases with time, and when λ τ80 reaches 700 nm, a high transmittance of 80% or more is maintained.

[0130] Further, in the present application, the thermal expansion coefficient α -50 / 80 is in the range of 60 to 81 x 10 -7 / °C. The optical glass has a bubble rating of 1, and the number of foreign substances (diameter Φ ≥ 0.03 mm) contained in the optical glass is 0. 3 The optical glass has a bubble rating of 1, and the number of foreign substances (diameter Φ ≥ 0.03 mm) contained in the optical glass is 0.

[0131] The high-refractive low-dispersion low-melting optical glass according to the present application has a sufficiently low liquidus temperature, and does not devitrify or crystallize during press molding or annealing. The optical glass according to the present application preferably has a high devitrification resistance, and more specifically, preferably has a low liquidus temperature. That is, the upper limit of the liquidus temperature of the optical glass according to the present application is preferably 1250°C, more preferably 1230°C, still more preferably 1200°C, and even more preferably 1180°C. Thus, even if the glass after melting is caused to flow at a lower temperature, crystallization of the produced glass is reduced, and thus devitrification when the glass is formed from a molten state is reduced, and the influence on the optical characteristics of an optical element using the glass can be reduced. In addition, even if the melting temperature of the glass is reduced, the glass can be formed, and thus the energy consumed during the formation of the glass can be reduced, and thus the manufacturing cost of the glass can be reduced.

[0132] On the other hand, the lower limit of the liquidus temperature of the optical glass according to the present application is not particularly limited, and the liquidus temperature of the glass obtained according to the present application is 1135°C or more. Note that the upper limit of the liquidus temperature in the present specification is obtained by placing 500 g of raw materials in a 300-ml platinum crucible, bringing the materials to a completely molten state at 1450°C, cooling to a predetermined temperature and maintaining the temperature for 1 hour, taking the glass out of the furnace, and immediately after cooling, observing whether or not crystals are present on the surface of the glass and in the glass, and the lowest temperature at which no crystals are observed is the upper limit of the liquidus temperature. The lower limit of the liquidus temperature is obtained by a gradient furnace test. That is, a glass sample prepared to have a size of 240 x 5 x 5 mm with both large faces polished is placed in a gradient furnace and maintained for 40 minutes, and the starting liquidus temperature of the glass is observed under a microscope, and this is the lower limit of the liquidus temperature.

[0133] The high refractive index glass contains a large amount of high refractive index components (e.g. La2O3, Gd2O3, TiO2, Nb2O5, ZrO2, etc.), and the melting points of these components are extremely high. Moreover, when the total amount of high refractive index components is large, the total amount of glass fluxing components such as B2O3, alkali metals, and alkaline earth metals is relatively reduced, which can result in a reduction in the glass melting property and devitrification resistance. In addition, in the case of a very high refractive index glass, alkali metals and alkaline earth metals, which can cause crystallization and a reduction in the refractive index of the glass, cannot be contained. Therefore, in order to obtain a homogeneous glass, the melting temperature must be increased. When the melting temperature is increased, the corrosiveness of the glass melt is increased, and the melting vessel, which is made of platinum or platinum alloy, for example, can dissolve into the glass melt, which can cause the glass to be colored or can result in the presence of platinum impurities.

[0134] In addition, when the melting temperature is high, volatile components such as B2O3 can volatilize, and the glass composition can change over time, which can cause a variation in optical properties. In order to solve such problems, the increase in the melting temperature must be suppressed. The melting temperature range can be considered to be a temperature range in which a homogeneous glass melt can be obtained, and the lower limit of the temperature range can be considered to vary substantially in accordance with the increase or decrease in the liquidus temperature. Therefore, the increase in the melting temperature can be suppressed by suppressing the increase in the liquidus temperature. In addition, by suppressing the increase in the liquidus temperature, devitrification during glass forming can be effectively prevented, and the viscosity of the glass can be adjusted to a range suitable for forming, which can facilitate the production of a high-quality glass formed body.

[0135] As described above, the increase or decrease in the refractive index and the increase or decrease in the liquidus temperature are related to the increase or decrease in the high refractive index glass components, and therefore, it is more meaningful to evaluate the melting property and devitrification resistance using the glass transition temperature Tg, the refractive index n d In the case of an optical glass, the higher the devitrification resistance Tg / Lt means that the melting property and devitrification resistance of the glass are more excellent when the liquidus temperature is set to Lt. The devitrification resistance Tg / Lt of the optical glass according to the present application is in the range of 0.59 to 0.66. Therefore, the glass has a greater devitrification resistance Tg / Lt, and the process stability of the glass is good, which is advantageous for the production and forming of the glass.

[0136] The very high refractive index low dispersion optical glass according to the present application is mainly used for the processing and molding of spherical and aspherical optical members, and is used in optical systems of optical instruments of various applications using the principles of transmission, refraction, reflection, and diffraction of gratings, such as spherical lenses, aspherical lenses, cylindrical lenses, diffraction gratings, prisms, and the like.

[0137] The present application also provides a method for preparing the optical glass according to the present application, which comprises weighing the raw materials of the optical glass according to the proportions, mixing them uniformly, then melting, and then shaping in a shaping mold. As a method for obtaining shaped glass using a shaping mold, molten glass can be caused to flow down one end of the shaping mold while the shaped glass is pulled out from the other end side of the shaping mold; or the glass can be formed by casting molten glass into a mold and annealing.

[0138] Specifically, the raw materials of the present application are mixed uniformly so that each component is within the specified content range, and the prepared mixture is placed in a platinum crucible, a platinum alloy crucible, or an iridium crucible. Depending on the ease of melting of the glass raw materials, the mixture is melted at a temperature in the range of 1300 to 1500°C for 2 to 5 hours, and stirred to homogenize. Then, defoaming is performed by taking appropriate stirring and fining processes for 5 to 20 hours at a temperature in the range of 1350 to 1480°C, and then final stirring is performed to remove streaks after the temperature is lowered to below 1370°C. Then, the glass is cast or poured into a shaping mold, and finally subjected to post-treatment such as annealing and processing, or directly pressed into shape by a press molding technique, to obtain the environmentally friendly optical glass or optical member having a very high refractive index.

[0139] According to the glass composition range of the present application, an environmentally friendly optical glass having a very high refractive index can be obtained. The optical glass has good thermal stability and chemical stability, and when used, the glass for optical members can be obtained by cutting, grinding, and surface polishing, or by directly pressing into shape by a press molding technique, grinding, and has excellent processability, good mold release properties, and is suitable for batch melting and press molding production.

[0140] Further, the present application also provides an optical member formed from the above optical glass according to a method known to those skilled in the art. Since the optical glass has a very high refractive index and a high glass transition temperature, it can be applied to devices such as digital cameras, digital video cameras, and camera phones.

[0141] Examples

[0142] The embodiments of the present application will be described in detail below with reference to examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be considered as limiting the scope of the present application. In the examples, the specific conditions are not specified, and the conventional conditions or the conditions recommended by the manufacturer are used. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be obtained commercially.

[0143] The optical glass comparative examples A to F shown in Table 5 were prepared by weighing and mixing common raw materials (such as oxides, hydroxides, carbonates, nitrates, Si3N4, Li2SO4, ZnSO4, etc.) according to the ratios shown in Tables 1 to 4. The mixed raw materials were placed in a platinum crucible and melted at 1350°C for 5 hours. Then, the temperature was raised to 1450°C for stirring and clarification to eliminate bubbles. The temperature was then lowered to 1300°C at a rate of -150°C / h and stirred and homogenized for 2 hours to remove streaks. The glass was then poured or poured into a molding die and finally subjected to post-processing such as annealing and machining, or pressed into shape using a secondary pressing technique. This environmentally friendly ultra-high refractive index optical glass or optical components can be obtained.

[0144] The composition and refractive index (n) of Examples 1-29 and Comparative Examples A-F of the present invention d Abbe number (υ) d ), thermal expansion coefficient α -50 / 80 Hardness HK, transition temperature Tg, sag temperature Ts, internal light transmittance λ τ80 The results for specific gravity ρ, devitrification resistance Tg / Lt, bubble grade, foreign matter number, etc., are presented together in Tables 1-5. The composition of each component is expressed as mass % (%).

[0145] The methods for testing the performance of optical glass are as follows:

[0146] 1. Refractive index n d and Abbe number υ d

[0147] The refractive index and Abbe number of the optical glass of this invention were determined according to the test method of GB / T7962.1-2010. d Abbe number υ d The determination of n is shown in Tables 1-5. d υ d The data is for annealing at -30℃.

[0148] 2. Glass transition temperature Tg and sag temperature Ts

[0149] The transition temperature (Tg) and sag temperature (Ts) of the optical glass of this invention are tested in accordance with GB / T7962.16-1987 Test Method for Linear Expansion Coefficient, Transition Temperature and Sag Temperature of Colorless Optical Glass. That is, within a certain temperature range, for every 1°C increase in temperature, the temperature corresponding to the intersection of the straight lines of the low temperature region and the high temperature region on the expansion curve of the test sample is determined.

[0150] 3. Knoop hardness (HK) of glass

[0151] Knoop hardness is measured according to the test method specified in ISO 9385.

[0152] 4. Internal transmission color

[0153] The transmission performance of the optical glass of the present application is expressed by the color (λ τ80 / λ τ5 ). The wavelengths λ 80 , λ τ80 corresponding to the internal transmittances of 80% and 5% for the glasses of 5 mm and 15 mm thickness can simply characterize the color degree of the glass. That is, the spectral transmittances of 200-800 nm for the parallel polished products of 5 ± 0.1 mm and 15 ± 0.1 mm in thickness are tested, and λ τ5 (λ in corresponding to the internal transmittance of 5%) are calculated. The internal transmittance refers to the transmittance expressed by I out / I out , which does not include the surface reflection loss on the above-mentioned surface of the glass, in the case where the light of intensity I in is perpendicularly incident on the above-mentioned surface of the glass, and the light of intensity I τ80 is transmitted through the glass and emitted from the other plane. Therefore, in the high refractive index glass, the value of λ -50 / 80 is small, which means that the color of the glass itself is little.

[0154] 5. Liquidus temperature

[0155] The liquidus temperature in the present application is expressed by Lt, and the specific method is as follows: the power is turned on, the furnace temperature is gradually increased at a certain rate, when the furnace temperature is higher than the predetermined temperature by 50℃, the furnace door is quickly opened, the ceramic container with the sample (4.5 × 4.5 × 250 mm, the sample with two large faces polished) placed therein is placed at the specified position in the gradient furnace. The thermocouple is inserted. When the furnace temperature is constant, the constant temperature is maintained for 0.5 hours, the gradient temperature curve is measured and drawn. The sample is taken out, cooled to room temperature in air, and the sample surface is observed for crystallization under a magnifying glass, the crystallization interval is determined, and the temperature at which the crystallization begins is the liquidus temperature.

[0156] 6. Coefficient of thermal expansion α -50 / 80

[0157] The measurement is carried out according to the method specified in GB / T 7962.16.

[0158] 7. Specific gravity

[0159] The measurement is carried out according to the test method in GB / T 7962.20-2010.

[0160] 8. Bubble grade

[0161] The bubble grade of the optical glass is expressed by the number of bubbles per 100 cm 3The cross-sectional area of ​​the bubbles (diameter Φ≥0.03mm) contained in the glass is used to determine the cross-sectional area, which is divided into 5 levels, as shown in Table A below. Stones, crystals, and other inclusions are also included in the bubble calculation. For elongated bubbles, the arithmetic mean of the longest and shortest axes is used as the diameter for calculating the cross-sectional area.

[0162] Table A

[0163]

[0164] 9. Number of foreign objects (pieces / 100cm) 3 )

[0165] Under a 50W spotlight, the number of foreign objects inside the glass was counted, and the number per 100cm was calculated. 3 The number of foreign objects (diameter Φ≥0.03mm) contained in the glass.

[0166] Table 1

[0167]

[0168] Table 2

[0169]

[0170] Table 3

[0171]

[0172] Table 4

[0173]

[0174] Table 5

[0175]

[0176] As can be seen from Tables 1 to 4, the optical glass provided by this invention has the following properties: a refractive index (nd) of 2.04 to 2.06, an Abbe number between 25 and 30, a transition temperature Tg below 750℃, specifically in the range of 735 to 750℃; a sag temperature Ts below 790℃, specifically in the range of 775 to 790℃; and an internal chromaticity λ. τ80 / λ τ5 λ τ80 No more than 422nm, λ τ5 Not exceeding 362 nm; liquidus temperature (Lt) below 1230℃; hardness (HK) between 690 and 715 × 10⁻⁶. 7 Within the Pa range, all bubbles are classified as Grade 1, with no foreign matter inside. Therefore, it exhibits excellent optical properties, mechanical properties, chemical stability, and processability, making it suitable for mass production.

[0177] As can be seen from Table 5, the optical glasses of Comparative Examples A to F have various problems, such as: the liquidus temperature Lt can be too high, the glass production process is not stable, and it is easy to produce foreign matters and bubbles, especially λ τ80 and λτ5 are obviously worse than the embodiments of the present application, and the transmission performance is poorer.

[0178] It should be noted that although the technical solutions of the present application are described with specific examples, those skilled in the art can understand that the present application should not be limited thereto.

[0179] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles, practical applications, or technical improvements in the market of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. An optical glass, characterized in that, The optical glass comprises SiO2, B2O3, La2O3, Gd2O3, TiO2, Nb2O5, and ZrO2; and, The optical glass further comprises one or more of Si3N4, BN, and Li3N; and... Based on the total mass of anions being 100%, O 2- The content is 79-99.5%, SO4 2- With N 3- The total content of SO4 is 0.5-21%. 2- The content is 0.1%–5.5%, N 3- The content is 0.4-15.5%; N 3- With SO4 2- and N 3- The ratio N of the sum of the contents of 3- / ∑(N 3- +SO4 2- The value ranges from 0.25 to 0.

98. Based on the total mass of the optical glass (100%), the content of Gd₂O₃ is 5-15%, the content of SiO₂ is 5-10%, the content of B₂O₃ is 4-6.5%, the content of La₂O₃ is 35-58%, the content of Nb₂O₅ is 5-15%, the content of TiO₂ is 10-20%, and the content of ZrO₂ is 3-8%; the ratio of Gd₂O₃ to the sum of the contents of La₂O₃, TiO₂, and ZrO₂, Gd₂O₃ / ∑(La₂O₃+TiO₂+ZrO₂), is 0.1-0.

3. The optical glass has a refractive index of 2.04 to 2.06 and an Abbe number of 25 to 30.

2. The optical glass according to claim 1, characterized in that, Based on 100% of the total mass of the optical glass, the optical glass also contains the following components: Y2O3: 0-5%; ZnO: 0-5%; Si3N4: 0-5%; BN: 0-5%; Li3N: 0-3%; Sb₂O₃: 0–0.05%; and, The contents of Si3N4, BN, and Li3N are not all 0.

3. The optical glass according to claim 2, characterized in that, Based on 100% of the total mass of the optical glass, the optical glass contains the following components: SiO2: 6-9%; B2O3: 4.5–6%; La2O3: 40-50%; Gd2O3: 8-15%; Y2O3: 0-4%; Nb2O5: 6%–13%; TiO2: 12-18%; ZnO: 0-3%; ZrO2: 4-7%; Si3N4: 0.1–4.5%; BN: 0-5%; Li2SO4: 0-1%; ZnSO4: 0-2%; Li3N: 0-3%; Sb₂O₃: 0–0.05%.

4. The optical glass according to any one of claims 1-3, characterized in that, The sum of the contents of SiO2 and B2O3, ∑(SiO2+B2O3), is 10-15% by mass percentage; and / or, The SiO2 to B2O3 content ratio (SiO2 / B2O3) is 1.0 to 2.

0.

5. The optical glass according to any one of claims 1-3, characterized in that, By weight percentage, The ratio of the sum of SiO2 and B2O3 contents to TiO2, ∑(SiO2+B2O3) / TiO2, is 0.5–1.3; and / or, The ratio of the sum of the contents of TiO2 and Nb2O5 to the sum of the contents of SiO2 and B2O3, ∑(TiO2+Nb2O5) / ∑(SiO2+B2O3), is 1.50 to 3.

0.

6. The optical glass according to any one of claims 1-3, characterized in that, By weight percentage, The sum of the contents of TiO2 and Nb2O5, ∑(TiO2+Nb2O5), is 18–30%; and / or, The Nb₂O₅ content to TiO₂ content ratio (Nb₂O₅ / TiO₂) is 0.35–2.5; and / or, The ratio of Nb2O5 content to the sum of Nb2O5 and TiO2 content, Nb2O5 / (TiO2+Nb2O5), is 0.25 to 0.

92.

7. The optical glass according to any one of claims 1-3, characterized in that, By weight percentage, The sum of the contents of La2O3, Y2O3, and Gd2O3, ∑(La2O3+Y2O3+Gd2O3), is 50–65%; and / or, The ratio of the sum of Gd₂O₃ and La₂O₃ contents to the Nb₂O₅ content, ∑(Gd₂O₃+La₂O₃) / Nb₂O₅, is 3.5–9.5; and / or, The ratio of the contents of Gd₂O₃ to the sum of the contents of La₂O₃, Y₂O₃, and Gd₂O₃, Gd₂O₃ / ∑(La₂O₃+Y₂O₃+Gd₂O₃), is 0.1 to 0.3; and / or, The ratio of the contents of La2O3 to the sum of the contents of Y2O3, Gd2O3 and ZrO2, La2O3 / ∑(Y2O3+Gd2O3+ZrO2), is 1.5 to 4.

5.

8. The optical glass according to any one of claims 1-3, characterized in that, The internal light transmittance chromaticity λτ of the optical glass 80 / λ τ5 In, λτ 80 Below 422nm, λτ5 is below 362nm; The transition temperature of the optical glass is below 750°C, and the sag temperature is below 790°C. The specific gravity ρ of the optical glass is below 5.37; The optical glass has a hardness HK of 690×10⁻⁶. 7 Pa or above.

9. A method for preparing optical glass according to any one of claims 1-8, characterized in that, The preparation method includes weighing and mixing the various component raw materials of optical glass in proportion, melting them, and then forming them into optical glass using a molding die.

10. An optical element, characterized in that, Includes the optical glass according to any one of claims 1-8.

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