Fluorotellurite glass with low hydroxyl absorption coefficient and multiband permeability and preparation method of fluorotellurite glass

Abstract

The invention relates to fluorotellurite glass with low hydroxyl absorption coefficient and multiband permeability and a preparation method thereof. The fluorotellurite glass with the low hydroxyl absorption coefficient and the multiband permeability is prepared from the following components in percentage by mole: 25 to 30 mol percent of AlF3, 10 to 15 mol percent of BaF2, 8 to 15 mol percent of LaF3, 5 to 10 mol percent of YF3, 5 to 10 mol percent of MgF2, 5 to 10 mol percent of SrF2 and 20 to 30 mol percent of TeO2, preferably, the composition comprises 25 to 30 mol% of AlF3, 10 to 15 mol% of BaF2, 10 to 15 mol% of LaF3, 5 to 10 mol% of YF3, 5 to 10 mol% of MgF2, 5 to 10 mol% of SrF2 and 20 to 30 mol% of TeO2.

Description

Technical Field

[0001] The present invention belongs to the technical field of mid-infrared glass preparation, and particularly relates to a low hydroxyl absorption coefficient, multi-band transmissive fluoro-tellurite glass and a preparation method thereof. Background Art

[0002] Mid-infrared optical materials with high transmittance in the 3-5um band are one of the key window materials for many important military and civilian systems, such as infrared countermeasure, infrared guidance, infrared reconnaissance, radar stealth, etc. The new generation of optoelectronic systems is developing towards the direction of multi-band compounding, and the working environments of these optoelectronic systems are often relatively harsh. Therefore, the required optical materials should not only have excellent transmittance, optical uniformity, physical and chemical properties, etc. in the visible-infrared band, but also have higher requirements in terms of the window scale (greater than 400mm) and the preparation of complex shapes. At present, the infrared materials that can be widely applied are extremely limited, and it is difficult for crystal materials to achieve large sizes and the manufacturing and processing costs are expensive.

[0003] Compared with crystal materials, glass has certain advantages in large-scale preparation. Conventional mid-wave infrared glasses (such as fluoride glasses) are difficult to prepare large-sized glasses due to their limited glass-forming ability. The lack of large-sized high-performance infrared window glass materials has become one of the important factors restricting the development of optoelectronic systems. Therefore, it is urgent to solve the problem of insufficient glass-forming ability of fluoride glasses at present.

[0004] Adding TeO2 to fluoride glasses can enhance the glass-forming ability while maintaining the excellent infrared performance of fluoride glasses, so as to achieve large-scale preparation. In addition, water removal of infrared glass is also very crucial for infrared performance. Therefore, how to achieve a low hydroxyl absorption coefficient is also an important technology in the preparation of multi-band transmissive window glasses. Summary of the Invention

[0005] Aiming at the above technical problems, the purpose of the present invention is to provide a low hydroxyl absorption coefficient, multi-band transmissive fluoro-tellurite glass and a preparation method thereof.

[0006] In the first aspect, the present invention provides a low hydroxyl absorption coefficient, multi-band transmissive fluoro-tellurite glass. The composition of the low hydroxyl absorption coefficient, multi-band transmissive fluoro-tellurite glass includes: in terms of mole percentage, 25-30 mol% AlF3, 10-15 mol% BaF2, 8-15 mol% LaF3, 5-10 mol% YF3, 5-10 mol% MgF2, 5-10 mol% SrF2, and 20-30 mol% TeO2; Preferably, 25-30 mol% AlF3, 10-15 mol% BaF2, 10-15 mol% LaF3, 5-10 mol% YF3, 5-10 mol% MgF2, 5-10 mol% SrF2, and 20-30 mol% TeO2.

[0007] Preferably, the hydroxyl absorption coefficient of the low-hydroxyl absorption coefficient and multi-band transmission fluoro-tellurite glass is not higher than 0.15 cm -1 .

[0008] Preferably, the transmittance of the low-hydroxyl absorption coefficient and multi-band transmission fluoro-tellurite glass between 370 and 5572 nm is above 80%, up to 91% at most, and the internal transmittance after removing surface reflection at 1500 nm reaches 99.00%; among them, the refractive index is not less than 1.520, the Abbe number is not less than 68, and the maximum refractive index difference does not exceed 0.06%.

[0009] Preferably, the glass transition temperature of the low-hydroxyl absorption coefficient and multi-band transmission fluoro-tellurite glass is 430-450 °C, the thermal stability parameter is greater than 100 °C, and the thermal expansion coefficient is lower than 15×10 -6 / K.

[0010] In a second aspect, the present invention provides a method for preparing the above-mentioned low-hydroxyl absorption coefficient and multi-band transmission fluoro-tellurite glass, and the preparation method includes the following steps: (1) Weigh AlF3, BaF2, LaF3, YF3, MgF2, SrF2, and TeO2 according to the composition of the above-mentioned low-hydroxyl absorption coefficient and multi-band transmission fluoro-tellurite glass, mix them and then dry them; (2) High-temperature melt the dried raw materials in a lifting furnace in a glove box filled with dry oxygen, and obtain glass liquid after clarification; (3) Cast, shape, anneal, and cool the glass liquid in dry oxygen to obtain the low-hydroxyl absorption coefficient and multi-band transmission fluoro-tellurite glass.

[0011] Preferably, place the mixed raw materials in a lifting furnace at 200-300 °C for drying, and the drying time is 8-12 h, preferably 8-10 h.

[0012] Preferably, the temperature of the high-temperature melting is 900-1000 °C, and the heat preservation time is 1-2 h.

[0013] Preferably, the processes of casting, shaping, annealing, and cooling are as follows: Pour the glass liquid into a graphite mold preheated to 400-450 °C; after cooling and shaping, transfer it to a lifting furnace at 400-450 °C for annealing and heat preservation for 8-15 h, preferably 10-15 h; then cool at a rate of 10-15 °C / hour.

[0014] Beneficial effects The content of tellurium dioxide in the fluoro-tellurite glass provided by the present invention is relatively small, which will not cause the glass to show abnormal colors (yellowish / greenish); at the same time, the fluoro-tellurite glass prepared through a low water environment combines the characteristics of fluoride glass such as high transmittance and low hydroxyl absorption coefficient, and has good application prospects in multi-band window materials. Description of the drawings

[0015] Figure 1 It is the transmittance spectrum diagram of the low hydroxyl absorption coefficient and multi-band transmissive fluoro-tellurite glass prepared in Example 1; Figure 2 It is the refractive index curve diagram of the low hydroxyl absorption coefficient and multi-band transmissive fluoro-tellurite glass prepared in Example 1; Figure 3 It is the DSC curve diagram of the low hydroxyl absorption coefficient and multi-band transmissive fluoro-tellurite glass prepared in Example 1; Figure 4 It is the thermal expansion coefficient curve diagram of the low hydroxyl absorption coefficient and multi-band transmissive fluoro-tellurite glass prepared in Example 1. Detailed implementation manners

[0016] The present invention will be further described through the implementation manners. It should be understood that the following implementation manners are only used to illustrate the present invention and do not limit the present invention.

[0017] First, the present invention provides a low hydroxyl absorption coefficient and multi-band transmissive fluoro-tellurite glass. The composition of the low hydroxyl absorption coefficient and multi-band transmissive fluoro-tellurite glass may include: in terms of mole percentage, 25-30 mol% AlF3, 10-15 mol% BaF2, 8-15 mol% LaF3, 5-10 mol% YF3, 5-10 mol% MgF2, 5-10 mol% SrF2, and 20-30 mol% TeO2; preferably, 25-30 mol% AlF3, 10-15 mol% BaF2, 10-15 mol% LaF3, 5-10 mol% YF3, 5-10 mol% MgF2, 5-10 mol% SrF2, and 20-30 mol% TeO2.

[0018] Among them, TeO2 has a strong glass - forming ability and a relatively wide mid - infrared transmission window. Therefore, as the main component of the matrix glass, TeO2 is conducive to obtaining high - performance mid - infrared fluoro - tellurite glass. AlF3 has a low phonon energy and weak covalent bonds, and also plays a key role in removing water from infrared glass. BaF2 can improve the thermal stability of the glass. LaF3 and SrF2 can compensate for the generally poor chemical stability in the weak - bond glass system (TeO2 - based glass). MgF2 can reduce the water solubility of the glass and improve the anti - hydrolysis ability of the glass. YF3 can improve the glass - forming ability and the solubility of rare - earth ions.

[0019] By controlling the composition of the above - mentioned fluoro - tellurite glasses within a specific molar ratio, the multi - band - transmitting fluoro - tellurite glass prepared by the present invention can have good visible - near - infrared - mid - infrared transmission, high thermal stability and good anti - crystallization ability, and is expected to be widely used in multi - band window materials.

[0020] In some embodiments, the hydroxyl absorption coefficient of the low - hydroxyl - absorption - coefficient, multi - band - transmitting fluoro - tellurite glass is not higher than 0.15 cm -1 .

[0021] In some embodiments, the transmittance of the low - hydroxyl - absorption - coefficient, multi - band - transmitting fluoro - tellurite glass between 370 and 5572 nm is above 80%, up to 91% at most, and the internal transmittance after removing surface reflection at 1500 nm can reach 99.00%; among them, the refractive index n d is not less than 1.520, the Abbe number is not less than 68, the maximum refractive - index difference does not exceed 0.06%, and it has good optical uniformity, being an excellent multi - band window material.

[0022] In some embodiments, the glass transition temperature T g of the low - hydroxyl - absorption - coefficient, multi - band - transmitting fluoro - tellurite glass is 430 to 450 °C, the thermal stability parameter △T=(T x -T g ) is greater than 100 °C (T x represents the onset crystallization temperature, and T g represents the glass transition temperature), and the thermal expansion coefficient is lower than 15×10 -6 / K, having a low thermal expansion coefficient.

[0023] The following is an exemplary method for preparing the low-hydroxyl absorption coefficient, multi-band transmittance fluorotellurite glass provided by the present invention. The method may include the following steps: weighing AlF3, BaF2, LaF3, YF3, MgF2, SrF2, and TeO2 according to the composition of the low-hydroxyl absorption coefficient, multi-band transmittance fluorotellurite glass described above, mixing them uniformly, and then drying them; then, melting the dried raw materials at high temperature in a lift furnace within a glove box filled with dry oxygen, and clarifying the resulting molten glass; and then, casting, shaping, annealing, and cooling the molten glass in dry oxygen to obtain the low-hydroxyl absorption coefficient, multi-band transmittance fluorotellurite glass.

[0024] In some embodiments, the raw materials may be mixed by wet ball milling, and the ball milling solvent may be anhydrous ethanol. Preferably, the raw materials may be mixed by adding anhydrous ethanol multiple times for ball milling, and the time for each ball milling may be 20-30 minutes.

[0025] In some embodiments, the uniformly mixed raw materials can be placed in a lifting furnace at 200-300° C. for drying. The drying time can be 8-12 hours, preferably 8-10 hours.

[0026] In some embodiments, the high-temperature melting temperature may be 900-1000° C., and the holding time may be 1-2 hours.

[0027] Too high a temperature or too long a holding time can easily lead to serious volatilization of components, while too low a temperature or too short a holding time can prevent the raw materials from being completely melted, thus affecting the quality of the glass.

[0028] Melting the dried raw materials at high temperatures in a glove box filled with dry oxygen can reduce the impact of hydroxyl groups on the infrared performance of the glass. Melting in a dry oxygen environment allows the preparation of infrared glass with a low hydroxyl absorption coefficient. The preparation method provided by the present invention avoids the problem of a significant decrease in transmittance caused by absorption of hydroxyl groups at ~2.9 μm after hydroxyl groups enter the glass system, thereby facilitating the production of high-performance infrared-transmitting, multi-band window glass. Therefore, a dry oxygen atmosphere is beneficial for the preparation of high-performance, multi-band transmissive glass with a low hydroxyl absorption coefficient.

[0029] In some embodiments, the pouring, forming, annealing, and cooling processes may be as follows: pouring the molten glass into a graphite mold preheated to 400-450°C, cooling and forming the mold, and rapidly transferring the mold to a 400-450°C lifting furnace for annealing and heat preservation for 8-15 hours, preferably 10-15 hours, and then cooling the mold at a rate of 10-15°C / hour.

[0030] Graphite molds are more stable and easier to demold. Preheating to 400-450°C can quickly eliminate stress in the glass and prevent it from shattering. At the same time, cooling too quickly from high temperatures may generate stress, resulting in a deterioration in the mechanical properties of the glass.

[0031] The low hydroxyl absorption coefficient and multi-band transmittance fluorotellurate glass obtained by the preparation method provided by the present invention has high transmittance characteristics in the visible-near infrared-mid-infrared bands, and has a low refractive index, low dispersion, and good thermal stability. It is expected to be widely used in the fields of multi-band window materials, optical fiber transmission, etc.

[0032] The following examples are further listed to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention belong to the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range. That is, those skilled in the art can make selections within a suitable range based on the description herein, and are not limited to the specific values ​​exemplified below.

[0033] Example 1

[0034] The method for preparing the multi-band transparent fluorotellurite glass with low hydroxyl absorption coefficient provided by the present invention comprises the following steps: (1) weighing raw materials according to molar percentages of 28 mol% AlF3, 15 mol% BaF2, 8 mol% LaF3, 10 mol% YF3, 10 mol% MgF2, 9 mol% SrF2, and 20 mol% TeO2 and mixing them uniformly by wet grinding; (2) Place the mixed raw materials in a lifting electric heating furnace at 200°C and dry for 12 hours; (3) The dried raw materials were placed in an alumina crucible and melted at 950°C for 1 hour in a glove box filled with dry oxygen to obtain glass liquid after clarification; (4) The glass liquid is poured into a graphite mold preheated to 420°C. After being slightly cooled and formed, it is quickly transferred to a lifting furnace at 420°C for annealing and heat preservation for 8 hours, and then cooled at a rate of 10°C / h to obtain a low hydroxyl absorption coefficient and multi-band transmittance fluorotellurate glass.

[0035] Figure 1 This is a transmittance spectrum of the multi-band fluorotellurite glass with a low hydroxyl absorption coefficient prepared in Example 1. As can be seen from the figure, the transmittance of the glass can reach over 90%, and the hydroxyl absorption peak near 3 μm is relatively small.

[0036] Figure 2Refractive index curve of the low hydroxyl absorption coefficient and multi-band transmissive fluorotellurite glass prepared in Example 1. It can be seen from the figure that the refractive index difference at different positions is small, and the optical uniformity of the glass is good.

[0037] Figure 3 DSC curve of the low hydroxyl absorption coefficient and multi-band transmissive fluorotellurite glass prepared in Example 1. It can be seen from the figure that the T of the glass g is 450 °C, the Tx temperature is 551 °C, and it has good thermal stability.

[0038] Figure 4 Thermal expansion coefficient curve of the low hydroxyl absorption coefficient and multi-band transmissive fluorotellurite glass prepared in Example 1. It can be seen from the figure that the thermal expansion coefficient between 20 - 400 °C is less than 1.5×10 -5 / K, and it has a small thermal expansion coefficient.

[0039] After double-sided polishing the low hydroxyl absorption coefficient and multi-band transmissive fluorotellurite glass prepared in Example 1 by 1.5 mm and performing characterization tests, it can be known that the transmittance between 370 - 5572 nm is 80 - 91.4%, and the hydroxyl absorption coefficient is 0.12 cm -1 ; the refractive index n d is 1.525, the maximum refractive index difference is 0.06%; the Abbe number is 68.25; the glass transition temperature T g is 450 °C; the thermal expansion coefficient at 300 °C is 14.5×10 -6 / K.

[0040] Although the content of the present invention has been introduced in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as a limitation of the present invention. After those skilled in the art have read the above content, various modifications and substitutions to the present invention will be obvious. Therefore, the protection scope of the present invention should be defined by the appended claims.

Claims

1. A low hydroxyl absorption coefficient, multi-band transmissive fluorotellurite glass, characterized in that, The composition of the low hydroxyl absorption coefficient and multi-band transmissive fluorotellurite glass includes: in terms of mole percentage, 25-30 mol% AlF3, 10-15 mol% BaF2, 8-15 mol% LaF3, 5-10 mol% YF3, 5-10 mol% MgF2, 5-10 mol% SrF2, and 20-30 mol% TeO2; Preferably, 25-30 mol% AlF3, 10-15 mol% BaF2, 10-15 mol% LaF3, 5-10 mol% YF3, 5-10 mol% MgF2, 5-10 mol% SrF2, and 20-30 mol% TeO2.

2. The low hydroxyl absorption coefficient, multi-band transmissive fluorotellurite glass according to claim 1, characterized in that, The hydroxyl absorption coefficient of the low hydroxyl absorption coefficient and multi-band transmitting fluorotellurite glass is not higher than 0.15 cm -1 .

3. The low hydroxyl absorption coefficient, multi-band transmissive fluoro-tellurite glass according to claim 1 or 2, characterized in that, The transmittance of the low hydroxyl absorption coefficient and multi-band transmissive fluorotellurite glass between 370 and 5572 nm is above 80%, up to 91% at most, and the internal transmittance after removing surface reflection at 1500 nm reaches 99.00%; among them, the refractive index is not less than 1.520, the Abbe number is not less than 68, and the maximum refractive index difference does not exceed 0.06%.

4. The low hydroxyl absorption coefficient, multi-band transmissive fluoro-tellurite glass according to any one of claims 1-3, characterized in that, The glass transition temperature of the low hydroxyl absorption coefficient and multi-band transmissive fluorotellurite glass is 430 to 450 °C, the thermal stability parameter is greater than 100 °C, and the coefficient of thermal expansion is lower than 15×10 -6 / K.

5. A method for preparing a low hydroxyl absorption coefficient and multi-band transmissive fluoro-tellurite glass according to any one of claims 1-4, characterized in that, The preparation method includes the following steps: (1) Weigh AlF3, BaF2, LaF3, YF3, MgF2, SrF2, and TeO2 according to the composition of the low hydroxyl absorption coefficient and multi-band transmissive fluorotellurite glass as described above, mix them and then dry. (2) Perform high-temperature melting on the dried raw materials in a lifting furnace in a glove box filled with dry oxygen, and obtain glass melt after clarification. (3) Cast, shape, anneal, and cool the glass melt in dry oxygen to obtain the low hydroxyl absorption coefficient and multi-band transmissive fluorotellurite glass.

6. The preparation method according to claim 5, characterized in that, Place the mixed raw materials in a lifting furnace at 200-300 °C for drying, and the drying time is 8-12 h, preferably 8-10 h.

7. The preparation method according to claim 5 or 6, characterized in that, The temperature of the high-temperature melting is 900-1000 °C, and the heat preservation time is 1-2 h.

8. The preparation method according to any one of claims 5-7, characterized in that, The process of casting, shaping, annealing, and cooling is: pour the glass melt into a graphite mold preheated to 400-450 °C; after cooling and shaping, transfer it to a lifting furnace at 400-450 °C for annealing and heat preservation for 8-15 h, preferably 10-15 h; then cool at a rate of 10-15 °C per hour.

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