Submillimeter gradient refractive index infrared transparent chalcogenide glass and preparation method thereof

Abstract

The submillimeter gradient refractive index infrared transparent chalcogenide glass disclosed in the present invention is composed of n submillimeter chalcogenide glass layers with different refractive indices, where n is greater than or equal to 2. The refractive indices of the n chalcogenide glass layers along the axial direction of the chalcogenide glass decrease or increase in sequence with a fixed or non-fixed refractive index difference. Each chalcogenide glass layer contains two or more chalcogenide glass components with different refractive indices and are uniformly mixed. The glass transition temperature T of the two or more chalcogenide glass components is 2. g The temperature is higher than 300°C, the maximum refractive index difference of the n-layer chalcogenide glass is 0.3, the thickness of a single chalcogenide glass layer ranges from 50 to 500 μm, and the thickness of the n-layer chalcogenide glass layer ranges from 0.1 to 50 mm, with a diameter range of 3 to 50 mm. This chalcogenide glass has a high infrared transmittance of >60% in the 2-14 μm band, a refractive index difference of up to 0.3, and a tunable gradient refractive index structure, making it suitable for use in high-quality optical devices.

Description

Technical Field

[0001] The present invention relates to a preparation method of gradient refractive index infrared glass, in particular to a submillimeter grade gradient refractive index infrared transparent chalcogenide glass and a preparation method thereof. Background Art

[0002] The design of optical systems must balance cost, complexity, size, and weight while meeting performance and lifespan requirements. Emerging new optical manufacturing methods offer greater freedom in optical design. In traditional optical imaging systems, the material parameters of each optical component's internal structure are fixed constants. Optimizing lens system performance can only be achieved by independently modifying the structural parameters of each component. This is because when light of different wavelengths passes through a uniform lens, it produces varying degrees of Fresnel reflection on the lens surface, inevitably causing distortion in the optical system's image. Therefore, to avoid image distortion, traditional infrared optical systems are typically constructed from a combination of multiple infrared optical lenses with varying parameters. However, these systems suffer from complex optical systems, large size, and poor beam coupling. In particular, each lens surface reflects light, resulting in significant light attenuation and poor imaging quality. Gradient-index components designed with a specific refractive index distribution can not only achieve the same functions as traditional optical imaging systems, such as bending, focusing, and deflecting light, but can also significantly reduce light refractive loss and attenuation, the number of lenses, and weight, thereby improving the imaging performance of the optical system. Therefore, to meet the needs of military and civilian applications and complex environments, infrared optical imaging systems must develop in the direction of lightweight, integrated, high-density, and high-performance. There is an urgent need to develop new, high-quality infrared gradient refractive index lens materials, especially at the submillimeter scale, to promote the further development of infrared optical imaging systems.

[0003] Chalcogenide glass is considered an excellent infrared optical material due to its ultra-wide infrared transmission window (up to 2-25 μm), stable physical and chemical properties, low temperature refractive index (dn / dT), easy processing and preparation, and flexible and tunable composition. Consequently, chalcogenide glass has been widely used in dual-use infrared optical systems in recent years.

[0004] Existing methods for producing gradient refractive index glass mainly include ion exchange, molding and crystallization treatment. The ion exchange method has a long preparation cycle and a very shallow ion exchange depth, and is only suitable for the preparation of smaller-sized optical fiber gradient materials. In the molding method, not only will there be defects such as molding marks and bubbles during the molding process, but the mold and raw materials will also experience thermal expansion and contraction effects, resulting in large deviations in the size of the glass sample and poor controllability. In addition, the crystals present in the glass network after crystallization will cause relatively serious scattering of the incident light, resulting in poor imaging quality of the optical system. Currently reported are block-shaped and very long columnar glass, which is far from meeting the requirements of practical applications. Moreover, none of the above methods can accurately control the thickness of each refractive index layer of glass, making it difficult to achieve the preparation of gradient refractive index infrared chalcogenide glass at the submillimeter scale.

[0005] Screen printing technology deposits glass pastes with different refractive indices on a glass substrate through a screen. The thickness of the glass can be controlled by the height between the screen and the glass substrate and the viscosity of the glass paste. Then, a heat treatment and sintering process are combined to remove organic matter and densify the glass, thereby obtaining glass with a gradient refractive index. Because screen printing technology can effectively prepare submillimeter-scale glass sheets, it has attracted widespread attention and has achieved some research results in the preparation of oxide gradient refractive index glass. Due to the glass transition temperature T of chalcogenide glass, the glass transition temperature T g The temperature is generally below 300°C and is susceptible to oxidation and hydrolysis. The temperature for complete organic removal is generally above 300°C. Heat treatment above 300°C to remove organic matter can easily lead to severe crystallization of chalcogenide glass, and heat treatment and sintering must be performed under an inert gas atmosphere. Therefore, screen printing technology has not yet been used to prepare gradient refractive index glass in chalcogenide glass. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a submillimeter-level gradient refractive index infrared transparent chalcogenide glass and a preparation method thereof in response to the shortcomings of the existing technology. The chalcogenide glass has a high infrared transmittance of >60% in the 2-14μm band, a refractive index difference of up to 0.3, and its gradient refractive index structure is tunable, which can be applied to optical devices with high optical quality.

[0007] The technical solution adopted by the present invention to solve the above technical problems is: a submillimeter graded refractive index infrared transparent chalcogenide glass, wherein the chalcogenide glass is composed of n layers of submillimeter chalcogenide glass with different refractive indices, where n is greater than or equal to 2, and the refractive indices of the n layers of chalcogenide glass along the axial direction of the chalcogenide glass decrease or increase in sequence with a fixed or non-fixed refractive index difference, and each chalcogenide glass layer contains two or more chalcogenide glass components with different refractive indices and uniformly mixed, and the glass transition temperature T of the two or more chalcogenide glass components is 1. gThe temperature is higher than 300°C, the maximum refractive index difference of the n-layer chalcogenide glass layer is 0.3, the thickness of the single-layer chalcogenide glass layer is 50 to 500 μm, the thickness of the n-layer chalcogenide glass layer is 0.1 to 50 mm, and the diameter range is 3 to 50 mm.

[0008] Preferably, the molar composition of the glass system selected from the two or more chalcogenide glass components is represented by the chemical formula (100-x)Ga2S3-xLa2S3 and / or (100-x)Ga2S3-xGeS2, where 10≤x≤80. The chalcogenide glass components constituting the submillimeter gradient refractive index infrared-transparent chalcogenide glass of the present invention can be selected from one or both of the above-mentioned two glass systems. Both the (100-x)Ga2S3-xLa2S3 and (100-x)Ga2S3-xGeS2 glass systems have high glass transition temperatures and softening temperatures, enabling the removal of organic binders and the completion of the sintering process without affecting the gradient refractive index structure, thereby ensuring the efficient preparation of submillimeter gradient refractive index infrared-transparent chalcogenide glass.

[0009] Preferably, the glass transition temperature difference ΔT of the two or more chalcogenide glass components is g The temperature is 0-40°C, and the refractive index difference is 0.01-0.3.

[0010] A method for preparing the above-mentioned submillimeter gradient refractive index infrared transparent chalcogenide glass comprises: uniformly mixing two or more chalcogenide glass components with different refractive indices in different mass ratios to obtain a plurality of different composite glass powders; then uniformly mixing the plurality of different composite glass powders with organic binders in different mass ratios to obtain a plurality of different chalcogenide glass pastes with gradient refractive indices; then sequentially depositing the plurality of different chalcogenide glass pastes with gradient refractive indices on a glass substrate using a screen printing process; finally, removing the organic binder and sintering to obtain the submillimeter gradient refractive index infrared transparent chalcogenide glass.

[0011] The specific preparation steps of the above-mentioned submillimeter gradient refractive index infrared transparent chalcogenide glass are as follows:

[0012] (1) Preparation of composite glass powder: First, two or more bulk chalcogenide glasses of different components with different refractive indices are prepared by a vacuum melting and quenching method. The bulk chalcogenide glasses of different components are then ground into glass powders using a ball mill. The glass powders of different components are then mixed uniformly in different mass ratios to obtain a variety of different composite glass powders.

[0013] (2) Preparation of chalcogenide glass paste: a plurality of different composite glass powders and organic binders are uniformly mixed in different mass ratios to obtain a plurality of different chalcogenide glass pastes with gradient refractive index;

[0014] (3) Preparation of submillimeter gradient refractive index infrared transparent chalcogenide glass: A variety of different chalcogenide glass pastes with gradient refractive index are sequentially deposited on a glass substrate using a screen printing process. After each deposition, the glass substrate is placed in a vacuum drying oven and heat-treated to remove the organic binder in the paste. After all the different chalcogenide glass pastes are deposited and heat-treated, a glass precursor with a gradient refractive index is obtained on the glass substrate. The glass substrate is then placed in a tubular furnace protected by an inert gas atmosphere and the glass precursor is sintered. The sintering temperature is lower than the vacuum melting temperature of the chalcogenide glass component, so that the glass precursor is densified to form a transparent n-layer chalcogenide glass layer, thereby preparing submillimeter gradient refractive index infrared transparent chalcogenide glass.

[0015] Preferably, in step (1), the bulk chalcogenide glasses of different components are ball milled at a rotation speed of 200 to 500 rpm for 1 to 4 hours to form glass powders with a particle size of 0.1 to 500 μm.

[0016] Preferably, in step (2), the organic adhesive is prepared by mixing ethyl cellulose, terpineol, and diethylene glycol butyl ether in a mass ratio of (4-40):(20-70):(20-70) in a solvent bottle and mixing at a temperature of 50-100° C. for 1-6 hours. The present invention uses the organic adhesive with the above ratio to ensure that the viscosity of the chalcogenide glass paste meets the requirements, wherein the ethyl cellulose determines the viscosity of the organic adhesive. The higher the proportion of ethyl cellulose, the higher the viscosity of the organic adhesive.

[0017] Preferably, in step (3), the glass substrate used has a transparent window covering 2 to 14 μm and a melting point higher than the sintering temperature of the slurry; before screen printing, the glass substrate is pretreated, that is, the glass substrate is first ultrasonically cleaned with ethanol and deionized water for 5 to 20 minutes, blown dry with nitrogen, and then placed in an oven at 100 to 120° C. for 10 to 30 minutes to remove residual water on the surface of the glass substrate.

[0018] Preferably, in step (3), the heat treatment is divided into two stages: in the first stage, the temperature is raised to 100-180°C at a rate of 0.1-1°C / min and kept at this temperature for 0.5-4 hours; in the second stage, the temperature is raised to 300-450°C at a rate of 0.1-1°C / min and kept at this temperature for 0.5-4 hours. The purpose of the first stage heat treatment is to remove terpineol and diethylene glycol butyl ether from the slurry, and the purpose of the second stage heat treatment is to remove ethyl cellulose from the slurry. The above-mentioned staged heat treatment can achieve the staged and thorough removal of organic matter.

[0019] Preferably, in step (3), the sintering process is as follows: first, the temperature is raised to the sintering temperature at a rate of 1 to 10°C / min, and kept at this temperature for 0.5 to 2 hours to densify the glass precursor to form transparent glass; then, the temperature is lowered to the annealing temperature of 450 to 550°C at a rate of 5 to 20°C / min, and kept at this temperature for 1 to 4 hours to remove the internal stress of the glass.

[0020] Compared with the prior art, the present invention has very significant beneficial effects:

[0021] 1) The submillimeter-grade gradient refractive index infrared-transparent chalcogenide glass of the present invention is composed of multiple submillimeter-grade chalcogenide glass layers with different refractive indices. It has a high infrared transmittance of >60% in the 2-14 μm band, a refractive index difference of up to 0.3, and its gradient refractive index structure is tunable, which can be applied to optical devices with high optical quality.

[0022] 2) The preparation method of the present invention obtains a variety of different composite glass powders by controlling the mixing ratio of glass powders of different components, and obtains a variety of different chalcogenide glass pastes with gradient refractive indices by controlling the mixing ratio of different composite glass powders and organic binders. Combined with the screen printing process, the refractive index gradient distribution and glass size of the chalcogenide glass can be effectively controlled, achieving high-precision and high-efficiency preparation of submillimeter-level gradient refractive index infrared transparent chalcogenide glass with a single chalcogenide glass layer thickness of 50 to 500 μm, a total thickness of n chalcogenide glass layers of 0.1 to 50 mm, and a diameter range of 3 to 50 mm. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a process flow chart for preparing submillimeter gradient refractive index infrared transparent chalcogenide glass in Examples 1 to 4;

[0024] Figure 2 Schematic diagram of the screen printing process used to prepare submillimeter gradient refractive index infrared transparent chalcogenide glass in Examples 1 to 4;

[0025] Figure 3 Schematic diagram of a partial cross section of a submillimeter-scale gradient refractive index infrared transparent chalcogenide glass composed of six submillimeter-scale chalcogenide glass layers with different refractive indices prepared in Example 1;

[0026] Figure 4 This is the refractive index distribution diagram of the submillimeter gradient refractive index infrared transparent chalcogenide glass prepared in Example 1. DETAILED DESCRIPTION

[0027] In order to better understand the present invention, the present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto. For process parameters not particularly described, reference can be made to conventional techniques.

[0028] Example 1: Submillimeter gradient refractive index infrared transparent chalcogenide glass was prepared using two chalcogenide glass components 40Ga2S3-60La2S3 and 75Ga2S3-25La2S3 of the same glass system, such as Figure 1 As shown, the specific preparation steps are as follows:

[0029] (1) According to the molar compositions of the two chalcogenide glass components 40Ga2S3-60La2S3 and 75Ga2S3-25La2S3, using 5N purity Ga2S3 and La2S3 as raw materials, the weight of each raw material was calculated and weighed using a precision electronic balance in a glove box filled with inert gas and dry;

[0030] The bulk chalcogenide glasses A1 (corresponding to the composition of 40Ga2S3-60La2S3) and B1 (corresponding to the composition of 75Ga2S3-25La2S3) with two chalcogenide glass compositions were prepared by vacuum melting and quenching method. The preparation process is as follows: the weighed raw materials are placed in a quartz tube, and the vacuum is evacuated to 10 -3 MPa, then placed in a rocking furnace and melted at 1000-1200°C for 8-16 hours, then quenched in cold water when the temperature drops to 950°C, and immediately placed in an annealing furnace and kept at 450-550°C for 2-4 hours for annealing, thereby obtaining bulk chalcogenide glasses A1 and B1;

[0031] The bulk chalcogenide glasses A1 and B1 were respectively placed in a ball mill and milled at a speed of 500 rpm for 2 h to obtain glass powders A1 and B1;

[0032] (2) glass powders A1 and B1 were mixed uniformly according to six mass ratios of 1:0, 0.8:0.2, 0.6:0.4, 0.4:0.6, 0.2:0.8, and 0:1, respectively, to obtain six different composite glass powders, which were sequentially recorded as composite glass powders 1 to 6;

[0033] (3) Ethyl cellulose, terpineol, and diethylene glycol butyl ether were weighed using a precision electronic balance, and ethyl cellulose, terpineol, and diethylene glycol butyl ether were placed in a solvent bottle at a mass ratio of 4:48:48, placed on a magnetic stirrer, and stirred at 70°C for 2 h until transparent to obtain an organic adhesive;

[0034] (4) mixing the composite glass powders 1 to 6 with the organic binder in a mass ratio of 5:4 and stirring uniformly to obtain six chalcogenide glass pastes 1 to 6;

[0035] (5) Figure 2As shown in FIG, a 300 μm thick layer of chalcogenide glass paste 1 is first deposited on the surface of a clean glass substrate using a screen printing process. The glass substrate is then placed in a vacuum drying oven for heat treatment to remove the organic binder in the paste. The heat treatment is divided into two stages: in the first stage, the temperature is raised to 150°C at a rate of 0.2°C / min and kept at this temperature for 0.5 h; in the second stage, the temperature is raised to 450°C at a rate of 0.2°C / min and kept at this temperature for 0.5 h.

[0036] (6) Repeating step (5) to sequentially deposit 2 to 6 chalcogenide glass pastes, after all 6 chalcogenide glass pastes are deposited and heat-treated, a glass precursor having a gradient refractive index is obtained on the glass substrate;

[0037] (7) The glass substrate is placed in a tubular furnace protected by an inert gas atmosphere to sinter the glass precursor. The sintering process is as follows: first, the temperature is raised from room temperature to a sintering temperature of 830°C at a rate of 5°C / min and kept at this temperature for 1 hour, then the temperature is lowered to an annealing temperature of 500°C at a rate of 10°C / min and kept at this temperature for 1 hour, and then the temperature is naturally lowered to room temperature with the furnace body, completing the sintering, densifying the glass precursor to form a transparent 6-layer chalcogenide glass layer, thereby preparing a submillimeter-level gradient refractive index infrared transparent chalcogenide glass sample. The thickness of the single-layer chalcogenide glass layer is 100 μm, and the total thickness of the 6-layer chalcogenide glass layer is 600 μm, which is dense and transparent. The partial cross-sectional diagram is shown as follows. Figure 3 As shown in the figure, numbers 1 to 6 represent six chalcogenide glass layers arranged in sequence along the axial direction of the chalcogenide glass.

[0038] The submillimeter-scale gradient refractive index infrared-transparent chalcogenide glass sample prepared in Example 1 was processed and optically polished, and characterized using Fourier transform infrared spectroscopy. The results showed that the glass sample was unaffected by organic matter and the sintering process and exhibited high infrared transmittance in the 2-14 μm band.

[0039] The method of Example 1 was used to deposit chalcogenide glass pastes 1 to 6 on six clean glass substrates to prepare six single-layer infrared chalcogenide glass samples 1 to 6. These samples were processed and optically polished, and then the refractive index of each single-layer infrared chalcogenide glass sample was measured using an infrared ellipsometer to obtain the refractive index distribution of the submillimeter gradient refractive index infrared transparent chalcogenide glass sample prepared in Example 1. The maximum refractive index difference of the six chalcogenide glass layers reached 0.3, as shown in FIG. Figure 4 shown.

[0040] Example 2: Submillimeter gradient refractive index infrared transparent chalcogenide glass is prepared using two chalcogenide glass components 40Ga2S3-60La2S3 and 60Ga2S3-40La2S3 of the same glass system, such as Figure 1As shown, the specific preparation steps are as follows:

[0041] (1) According to the molar compositions of the two chalcogenide glass components 40Ga2S3-60La2S3 and 60Ga2S3-40La2S3, using 5N purity Ga2S3 and La2S3 as raw materials, the weight of each raw material was calculated and weighed using a precision electronic balance in a glove box filled with inert gas and dry;

[0042] The bulk chalcogenide glasses A2 (corresponding to the composition of 40Ga2S3-60La2S3) and B2 (corresponding to the composition of 60Ga2S3-40La2S3) with two chalcogenide glass compositions were prepared by vacuum melting and quenching method. The preparation process is as follows: the weighed raw materials are placed in a quartz tube, and the vacuum is evacuated to 10 -3 MPa, then placed in a rocking furnace at 1000-1200 ° C for 8-16 hours, then quenched in cold water when the temperature drops to 950 ° C, and immediately placed in an annealing furnace at 450-550 ° C for 2-4 hours for annealing, thereby obtaining bulk chalcogenide glasses A2 and B2;

[0043] The bulk chalcogenide glasses A2 and B2 were respectively placed in a ball mill and ball milled at a speed of 400 rpm for 3 h to obtain glass powders A2 and B2;

[0044] (2) glass powders A2 and B2 were mixed uniformly according to 21 mass ratios of 1:0, 0.95:0.05, 0.9:0.1, 0.85:0.15, 0.8:0.2, 0.75:0.25, 0.7:0.3, 0.65:0.35, 0.6:0.4, 0.55:0.45, 0.5:0.5, 0.45:0.55, 0.4:0.6, 0.35:0.65, 0.3:0.7, 0.25:0.75, 0.2:0.8, 0.15:0.85, 0.1:0.9, 0.05:0.95, and 0:1, respectively, to obtain 21 different composite glass powders, which were sequentially recorded as composite glass powders 1 to 21;

[0045] (3) Ethyl cellulose, terpineol, and diethylene glycol butyl ether were weighed using a precision electronic balance, and ethyl cellulose, terpineol, and diethylene glycol butyl ether were placed in a solvent bottle at a mass ratio of 10:40:50, placed on a magnetic stirrer, and stirred at 60° C. for 3 h until transparent to obtain an organic adhesive;

[0046] (4) mixing the composite glass powders 1 to 21 with the organic binder in a mass ratio of 5:4 and stirring them uniformly to obtain 21 chalcogenide glass pastes 1 to 21;

[0047] (5) Figure 2As shown, a 150 μm thick layer of chalcogenide glass paste 1 is first deposited on the surface of a clean glass substrate using a screen printing process. The glass substrate is then placed in a vacuum drying oven for heat treatment to remove the organic binder in the paste. The heat treatment is divided into two stages: in the first stage, the temperature is raised to 160°C at a rate of 0.1°C / min and kept at this temperature for 1 hour; in the second stage, the temperature is raised to 380°C at a rate of 0.1°C / min and kept at this temperature for 1 hour.

[0048] (6) Repeating step (5) to sequentially deposit 2 to 21 chalcogenide glass pastes, after all 21 chalcogenide glass pastes are deposited and heat-treated, a glass precursor having a gradient refractive index is obtained on the glass substrate;

[0049] (7) The glass substrate is placed in a tubular furnace protected by an inert gas atmosphere to sinter the glass precursor. The sintering process is as follows: first, the temperature is raised from room temperature to a sintering temperature of 850°C at a rate of 4°C / min and kept at this temperature for 1.5 hours, then the temperature is lowered to an annealing temperature of 480°C at a rate of 20°C / min and kept at this temperature for 2 hours, and then the temperature is naturally lowered to room temperature with the furnace body, completing the sintering and densifying the glass precursor to form 21 transparent chalcogenide glass layers, thereby preparing a submillimeter-level gradient refractive index infrared transparent chalcogenide glass sample. The thickness of the single chalcogenide glass layer is 90 μm, and the total thickness of the 21 chalcogenide glass layers is 1890 μm, which is dense and transparent.

[0050] The submillimeter-scale gradient refractive index infrared-transparent chalcogenide glass sample prepared in Example 2 was processed and optically polished, and characterized using Fourier transform infrared spectroscopy. The results showed that the glass sample was unaffected by organic matter and the sintering process and exhibited high infrared transmittance in the 2-14 μm band.

[0051] The method of Example 2 was used to deposit chalcogenide glass pastes 1 to 21 on 21 clean glass substrates to prepare 21 single-layer infrared chalcogenide glass samples 1 to 21. The samples were processed and optically polished, and then the refractive index of each single-layer infrared chalcogenide glass sample was measured using an infrared ellipsometer to obtain the refractive index distribution of the submillimeter gradient refractive index infrared transparent chalcogenide glass sample prepared in Example 2. The maximum refractive index difference of the 21 chalcogenide glass layers reached 0.21.

[0052] Example 3: Submillimeter gradient refractive index infrared transparent chalcogenide glass was prepared using three chalcogenide glass components 80Ga2S3-20La2S3, 75Ga2S3-25La2S3 and 70Ga2S3-30La2S3 of the same glass system, such as Figure 1 As shown, the specific preparation steps are as follows:

[0053] (1) According to the molar compositions of the three chalcogenide glass components 80Ga2S3-20La2S3, 75Ga2S3-25La2S3, and 70Ga2S3-30La2S3, using 5N purity Ga2S3 and La2S3 as raw materials, the weight of each raw material was calculated and weighed using a precision electronic balance in a glove box filled with inert gas and dry;

[0054] The bulk chalcogenide glasses A3 (corresponding to the composition of 80Ga2S3-20La2S3), B3 (corresponding to the composition of 75Ga2S3-25La2S3), and C3 (corresponding to the composition of 70Ga2S3-30La2S3) with two chalcogenide glass compositions were prepared by vacuum melting and quenching method. The preparation process is as follows: the weighed raw materials are placed in a quartz tube, and the vacuum is evacuated to 10 -3 MPa, then placed in a rocking furnace at 1000-1200 ° C for 8-16 hours, then quenched in cold water when the temperature drops to 950 ° C, and immediately placed in an annealing furnace at 450-550 ° C for 2-4 hours for annealing, thus obtaining bulk chalcogenide glasses A3, B3, and C3;

[0055] The bulk chalcogenide glasses A3, B3, and C3 were respectively placed in a ball mill and milled at a speed of 500 rpm for 2.5 h to obtain glass powders A2 and B2;

[0056] (2) Glass powders A3, B3, and C3 were mixed at a ratio of 1:0:0, 0.9:0.1:0, 0.8:0.2:0, 0.7:0.3:0, 0.6:0.4:0, 0.5:0.5:0, 0.4:0.6:0, 0.3:0.7:0, 0.2:0.8:0, 0.1:0.9:0, 0:1.0:0, 0:0.95:0.05, 0:0.9:0.1, 0:0.85:0.15, 0:0.8:0.2, 0:0.75:0.25, 0:0.7:0.3, 0:0.65:0.35, 0:0.6:0.4, 0:0.55:0.45, 0:0.5:0.5, 0:0.45:0.55, 0:0.4:0.6, 0:0.35:0.65, 0:0.3:0.7, 0:0.25:0.75, 0:0.2:0.8, 0:0.15:0.85, 0:0.1:0.9, 0:0.05:0.95, 0:0:1, these 31 mass ratios were mixed evenly to obtain 31 different composite glass powders, which were sequentially recorded as composite glass powders 1 to 31;

[0057] (3) Ethyl cellulose, terpineol, and diethylene glycol butyl ether were weighed using a precision electronic balance, and ethyl cellulose, terpineol, and diethylene glycol butyl ether were placed in a solvent bottle at a mass ratio of 20:50:30, placed on a magnetic stirrer, and stirred at 80° C. for 3 h until transparent to obtain an organic adhesive;

[0058] (4) mixing the composite glass powders 1 to 31 with the organic binder at a mass ratio of 10:4 and stirring uniformly to obtain 31 chalcogenide glass pastes 1 to 31;

[0059] (5) Figure 2 As shown in FIG, a 500 μm thick layer of chalcogenide glass paste 1 is first deposited on the surface of a clean glass substrate using a screen printing process. The glass substrate is then placed in a vacuum drying oven for heat treatment to remove the organic binder in the paste. The heat treatment is divided into two stages: in the first stage, the temperature is raised to 160°C at a rate of 0.5°C / min and kept at this temperature for 1.5 hours; in the second stage, the temperature is raised to 400°C at a rate of 0.6°C / min and kept at this temperature for 1 hour.

[0060] (6) Repeating step (5) to sequentially deposit 2 to 31 chalcogenide glass pastes, after all 31 chalcogenide glass pastes are deposited and heat-treated, a glass precursor having a gradient refractive index is obtained on the glass substrate;

[0061] (7) The glass substrate is placed in a tubular furnace protected by an inert gas atmosphere to sinter the glass precursor. The sintering process is as follows: first, the temperature is raised from room temperature to a sintering temperature of 900°C at a rate of 6°C / min and kept at this temperature for 1.5 hours, then the temperature is lowered to an annealing temperature of 480°C at a rate of 15°C / min and kept at this temperature for 2 hours, and then the temperature is naturally lowered to room temperature with the furnace body, completing the sintering and densifying the glass precursor to form 31 transparent chalcogenide glass layers, thereby preparing a submillimeter-level gradient refractive index infrared transparent chalcogenide glass sample. The thickness of the single chalcogenide glass layer is 200 μm, and the total thickness of the 31 chalcogenide glass layers is 6100 μm, which is dense and transparent.

[0062] The submillimeter-scale gradient refractive index infrared-transparent chalcogenide glass sample prepared in Example 3 was processed and optically polished, and characterized using Fourier transform infrared spectroscopy. The results showed that the glass sample was unaffected by organic matter and the sintering process and exhibited high infrared transmittance in the 2-14 μm band.

[0063] The method of Example 3 was used to deposit chalcogenide glass pastes 1 to 31 on 31 clean glass substrates to prepare 31 single-layer infrared chalcogenide glass samples 1 to 31. These samples were processed and optically polished, and then the refractive index of each single-layer infrared chalcogenide glass sample was measured using an infrared ellipsometer to obtain the refractive index distribution of the submillimeter gradient refractive index infrared transparent chalcogenide glass sample prepared in Example 3. The maximum refractive index difference of the 31 chalcogenide glass layers reached 0.29.

[0064] Example 4: Submillimeter gradient refractive index infrared transparent chalcogenide glass was prepared using two chalcogenide glass components 80Ga2S3-20GeS2 and 30Ga2S3-70GeS2 of the same glass system, such as Figure 1 As shown, the specific preparation steps are as follows:

[0065] (1) According to the molar compositions of the two chalcogenide glass components 80Ga2S3-20GeS2 and 30Ga2S3-70GeS2, using 5N purity Ga2S3 and GeS2 as raw materials, the weight of each raw material was calculated and weighed using a precision electronic balance in a glove box filled with inert gas and dry;

[0066] The bulk chalcogenide glasses A4 (corresponding to the composition of 80Ga2S3-20GeS2) and B4 (corresponding to the composition of 30Ga2S3-70GeS2) with two chalcogenide glass compositions were prepared by vacuum melting and quenching method. The preparation process is as follows: the weighed raw materials are placed in a quartz tube, and the vacuum is evacuated to 10 -3 MPa, then placed in a rocking furnace at 1000-1200 ° C for 8-16 hours, then quenched in cold water when the temperature drops to 950 ° C, and immediately placed in an annealing furnace at 450-550 ° C for 2-4 hours for annealing, thereby obtaining bulk chalcogenide glasses A4 and B4;

[0067] The bulk chalcogenide glasses A4 and B4 were respectively placed in a ball mill and milled at a speed of 350 rpm for 2 h to obtain glass powders A4 and B4;

[0068] (2) glass powders A4 and B4 were mixed uniformly in 11 mass ratios of 1:0, 0.9:0.1, 0.8:0.2, 0.7:0.3, 0.6:0.4, 0.5:0.5, 0.4:0.6, 0.3:0.7, 0.2:0.8, 0.1:0.9, and 0:1, respectively, to obtain 11 different composite glass powders, which were sequentially recorded as composite glass powders 1 to 11;

[0069] (3) Ethyl cellulose, terpineol, and diethylene glycol butyl ether were weighed using a precision electronic balance, and ethyl cellulose, terpineol, and diethylene glycol butyl ether were placed in a solvent bottle at a mass ratio of 20:50:30, placed on a magnetic stirrer, and stirred at 100° C. for 3 h until transparent to obtain an organic adhesive;

[0070] (4) mixing the composite glass powders 1 to 11 with the organic binder at a mass ratio of 20:4 and stirring uniformly to obtain 21 chalcogenide glass pastes 1 to 11;

[0071] (5) Figure 2 As shown, a 230 μm thick layer of chalcogenide glass paste 1 is first deposited on the surface of a clean glass substrate using a screen printing process. The glass substrate is then placed in a vacuum drying oven for heat treatment to remove the organic binder in the paste. The heat treatment is divided into two stages: in the first stage, the temperature is raised to 180°C at a rate of 0.5°C / min and kept at this temperature for 1.5 hours; in the second stage, the temperature is raised to 330°C at a rate of 0.6°C / min and kept at this temperature for 1.5 hours.

[0072] (6) Repeating step (5) to sequentially deposit 2 to 11 chalcogenide glass pastes, after all 11 chalcogenide glass pastes are deposited and heat-treated, a glass precursor having a gradient refractive index is obtained on the glass substrate;

[0073] (7) The glass substrate is placed in a tubular furnace protected by an inert gas atmosphere to sinter the glass precursor. The sintering process is as follows: first, the temperature is raised from room temperature to a sintering temperature of 700°C at a rate of 6°C / min and kept at this temperature for 1.5 hours, then the temperature is lowered to an annealing temperature of 400°C at a rate of 15°C / min and kept at this temperature for 2.5 hours. After that, the temperature is naturally lowered to room temperature with the furnace body, and the sintering is completed, so that the glass precursor is densified to form 11 transparent chalcogenide glass layers, thereby preparing a submillimeter-level gradient refractive index infrared transparent chalcogenide glass sample. The thickness of its single-layer chalcogenide glass layer is 120 μm, and the total thickness of the 11 chalcogenide glass layers is 1320 μm, which is dense and transparent.

[0074] The submillimeter-scale gradient refractive index infrared-transparent chalcogenide glass sample prepared in Example 4 was processed and optically polished, and characterized using Fourier transform infrared spectroscopy. The results showed that the glass sample was unaffected by organic matter and the sintering process and exhibited high infrared transmittance in the 2-14 μm band.

[0075] The method of Example 4 was used to deposit chalcogenide glass pastes 1 to 11 on 11 clean glass substrates to prepare 11 single-layer infrared chalcogenide glass samples 1 to 11. The samples were processed and optically polished, and then the refractive index of each single-layer infrared chalcogenide glass sample was measured using an infrared ellipsometer to obtain the refractive index distribution of the submillimeter gradient refractive index infrared transparent chalcogenide glass sample prepared in Example 4. The maximum refractive index difference of the 11 chalcogenide glass layers reached 0.25.

[0076] Example 5: Submillimeter-scale gradient refractive index infrared transparent chalcogenide glass was prepared using two chalcogenide glass components 40Ga2S3-60La2S3 and 70Ga2S3-30GeS2 of two glass systems, such as Figure 1 As shown, the specific preparation steps are as follows:

[0077] (1) According to the molar compositions of the two chalcogenide glass components 40Ga2S3-60La2S3 and 70Ga2S3-30GeS2, Ga2S3, La2S3, and GeS2 with a purity of 5N were used as raw materials, and the weights of the raw materials were calculated and weighed using a precision electronic balance in a glove box filled with inert gas and dry.

[0078] The bulk chalcogenide glasses A5 (corresponding to the composition of 40Ga2S3-60La2S3) and B5 (corresponding to the composition of 70Ga2S3-30GeS2) with two chalcogenide glass compositions were prepared by vacuum melting and quenching method. The preparation process is as follows: the weighed raw materials are placed in a quartz tube, and the vacuum is evacuated to 10 -3 MPa, then placed in a rocking furnace at 1000-1200 ° C for 8-16 hours, then quenched in cold water when the temperature drops to 950 ° C, and immediately placed in an annealing furnace at 450-550 ° C for 2-4 hours for annealing treatment to obtain bulk chalcogenide glasses A5 and B5;

[0079] The bulk chalcogenide glasses A5 and B5 were respectively placed in a ball mill and ball milled at a speed of 200 rpm for 4 h to obtain glass powders A5 and B5;

[0080] (2) glass powders A5 and B5 were mixed uniformly in 11 mass ratios of 1:0, 0.9:0.1, 0.8:0.2, 0.7:0.3, 0.6:0.4, 0.5:0.5, 0.4:0.6, 0.3:0.7, 0.2:0.8, 0.1:0.9, and 0:1, respectively, to obtain 11 different composite glass powders, which were sequentially recorded as composite glass powders 1 to 11;

[0081] (3) Ethyl cellulose, terpineol, and diethylene glycol butyl ether were weighed using a precision electronic balance, and ethyl cellulose, terpineol, and diethylene glycol butyl ether were placed in a solvent bottle at a mass ratio of 15:50:35, placed on a magnetic stirrer, and stirred at 90° C. for 3 h until transparent to obtain an organic adhesive;

[0082] (4) mixing the composite glass powders 1 to 11 with the organic binder in a mass ratio of 15:4 and stirring uniformly to obtain 11 chalcogenide glass pastes 1 to 11;

[0083] (5) Figure 2 As shown, a 300 μm thick layer of chalcogenide glass paste 1 is first deposited on the surface of a clean glass substrate using a screen printing process. The glass substrate is then placed in a vacuum drying oven for heat treatment to remove the organic binder in the paste. The heat treatment is divided into two stages: in the first stage, the temperature is raised to 170°C at a rate of 0.8°C / min and kept at this temperature for 2 hours; in the second stage, the temperature is raised to 340°C at a rate of 0.8°C / min and kept at this temperature for 1.5 hours.

[0084] (6) Repeating step (5) to sequentially deposit 2 to 11 chalcogenide glass pastes, after all 11 chalcogenide glass pastes are deposited and heat-treated, a glass precursor having a gradient refractive index is obtained on the glass substrate;

[0085] (7) The glass substrate is placed in a tubular furnace protected by an inert gas atmosphere to sinter the glass precursor. The sintering process is as follows: first, the temperature is raised from room temperature to a sintering temperature of 680°C at a rate of 6°C / min and kept at this temperature for 1.5 hours, then the temperature is lowered to an annealing temperature of 350°C at a rate of 13°C / min and kept at this temperature for 2.5 hours. After that, the temperature is naturally lowered to room temperature with the furnace body, and the sintering is completed, so that the glass precursor is densified to form 11 transparent chalcogenide glass layers, thereby preparing a submillimeter-level gradient refractive index infrared transparent chalcogenide glass sample. The thickness of its single-layer chalcogenide glass layer is 170 μm, and the total thickness of the 11 chalcogenide glass layers is 1870 μm, which is dense and transparent.

[0086] The submillimeter-scale gradient refractive index infrared-transparent chalcogenide glass sample prepared in Example 5 was processed and optically polished, and characterized using Fourier transform infrared spectroscopy. The results showed that the glass sample was unaffected by organic matter and the sintering process and exhibited high infrared transmittance in the 2-14 μm band.

[0087] The method of Example 5 was used to deposit chalcogenide glass pastes 1 to 11 on 11 clean glass substrates to prepare 11 single-layer infrared chalcogenide glass samples 1 to 11. The samples were processed and optically polished, and then the refractive index of each single-layer infrared chalcogenide glass sample was measured using an infrared ellipsometer to obtain the refractive index distribution of the submillimeter gradient refractive index infrared transparent chalcogenide glass sample prepared in Example 5. The maximum refractive index difference of the 11 chalcogenide glass layers reached 0.2.

Claims

1. A submillimeter gradient refractive index infrared transparent chalcogenide glass, characterized in that: The chalcogenide glass is composed of n layers of submillimeter chalcogenide glass layers with different refractive indices, where n is greater than or equal to 2. The refractive indices of the n layers of chalcogenide glass along the axial direction of the chalcogenide glass decrease or increase in sequence with a fixed or non-fixed refractive index difference. Each chalcogenide glass layer contains two or more chalcogenide glass components with different refractive indices and are uniformly mixed. The glass transition temperature of the two or more chalcogenide glass components is T g All are above 300 °C, the maximum refractive index difference of the n-layer chalcogenide glass layer is 0.3, the thickness of the single-layer chalcogenide glass layer is 50~500 μm, the thickness of the n-layer chalcogenide glass layer is 0.1~50 mm, and the diameter ranges from 3 to 50 mm; The chalcogenide glass preparation method comprises: uniformly mixing two or more chalcogenide glass components having different refractive indices in different mass ratios to obtain a plurality of different composite glass powders; uniformly mixing the plurality of different composite glass powders with organic binders in different mass ratios to obtain a plurality of different chalcogenide glass pastes having a gradient refractive index; sequentially depositing the plurality of different chalcogenide glass pastes having a gradient refractive index on a glass substrate using a screen printing process; and finally removing the organic binder and sintering to obtain a submillimeter-level gradient refractive index infrared-transparent chalcogenide glass. The specific preparation steps of the preparation method are as follows: (1) Preparation of composite glass powder: First, two or more bulk chalcogenide glasses of different components with different refractive indices are prepared by vacuum melting and quenching method. Then, the bulk chalcogenide glasses of different components are ground into glass powders by ball mill. Then, the glass powders of different components are mixed evenly according to different mass ratios to obtain a variety of different composite glass powders. (2) Preparation of chalcogenide glass paste: a variety of different composite glass powders and organic binders are mixed uniformly according to different mass ratios to obtain a variety of different chalcogenide glass pastes with gradient refractive index; (3) Preparation of submillimeter gradient refractive index infrared transparent chalcogenide glass: A variety of different chalcogenide glass pastes with gradient refractive index are deposited on a glass substrate in sequence using a screen printing process. After each deposition, the glass substrate is placed in a vacuum drying oven and heat-treated to remove the organic binder in the paste. After all the different chalcogenide glass pastes are deposited and heat-treated, a glass precursor with a gradient refractive index is obtained on the glass substrate. The glass substrate is then placed in a tubular furnace protected by an inert gas atmosphere and the glass precursor is sintered. The sintering temperature is lower than the vacuum melting temperature of the chalcogenide glass component, so that the glass precursor is densified to form a transparent n-layer chalcogenide glass layer, thereby preparing submillimeter gradient refractive index infrared transparent chalcogenide glass.

2. The submillimeter gradient refractive index infrared transparent chalcogenide glass according to claim 1, characterized in that: The molar composition of the glass system selected from the two or more chalcogenide glass components is expressed by the chemical formula (100-x)Ga2S3-xLa2S3 and / or (100-x)Ga2S3-xGeS2, where 10≤x≤80.

3. The submillimeter gradient refractive index infrared transparent chalcogenide glass according to claim 1, characterized in that: The glass transition temperature difference D between the two or more chalcogenide glass components T g The temperature is 0~40 ℃, and the refractive index difference is 0.01~0.

3.

4. The submillimeter gradient refractive index infrared transparent chalcogenide glass according to claim 1, characterized in that: In step (1), the bulk chalcogenide glass of different components is ball milled at a rotation speed of 200-500 rpm for 1-4 h to form glass powder with a particle size of 0.1-500 mm.

5. The submillimeter gradient refractive index infrared transparent chalcogenide glass according to claim 1, characterized in that: In step (2), the organic adhesive is prepared by mixing ethyl cellulose, terpineol, and diethylene glycol butyl ether in a solvent bottle in a mass ratio of (4-40):(20-70):(20-70), and then mixing at a temperature of 50-100°C for 1-6 hours.

6. The submillimeter gradient refractive index infrared transparent chalcogenide glass according to claim 1, characterized in that: In step (3), the glass substrate used has a transparent window covering 2~14 mm and a melting point higher than the sintering temperature of the slurry; before screen printing, the glass substrate is pretreated, that is, the glass substrate is first ultrasonically cleaned with ethanol and deionized water for 5~20 minutes, blown dry with nitrogen, and then placed in an oven at 100~120°C for 10~30 minutes to remove residual water on the surface of the glass substrate.

7. The submillimeter gradient refractive index infrared transparent chalcogenide glass according to claim 1, characterized in that: In step (3), the heat treatment is divided into two stages: in the first stage, the temperature is raised to 100-180°C at a rate of 0.1-1°C / min and kept at this temperature for 0.5-4 h; in the second stage, the temperature is raised to 300-450°C at a rate of 0.1-1°C / min and kept at this temperature for 0.5-4 h.

8. The submillimeter gradient refractive index infrared transparent chalcogenide glass according to claim 1, characterized in that: In step (3), the sintering process is as follows: first, the temperature is raised to the sintering temperature at a rate of 1-10 °C / min, and kept at this temperature for 0.5-2 h, then the temperature is lowered to the annealing temperature of 450-550 °C at a rate of 5-20 °C / min, and kept at this temperature for 1-4 h.

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