CsSnCl3 nanocrystalline doped chalcogenide glass and acousto-optic application thereof

Abstract

The invention discloses CsSnCl3 nanocrystal doped chalcogenide glass and acousto-optic application of the CsSnCl3 nanocrystal doped chalcogenide glass, the molar composition formula of the chalcogenide glass is 97 (0.8 GeS2-0.2 Sb2S3)-3 CsSnCl3, and CsSnCl3 nanocrystals separated out in situ through heat treatment are dispersed in the chalcogenide glass. The chalcogenide glass has the advantages as follows: the chalcogenide glass has excellent thermal mechanical properties and high robustness, the comprehensive characteristics are outstanding, the Vickers hardness, the elastic modulus, the thermo-optical coefficient, the laser damage threshold and other parameters of the chalcogenide glass are remarkably improved compared with those of current mainstream acousto-optic chalcogenide glass, and a guarantee is provided for stable operation of a device in a high-temperature and high-power environment; the CsSnCl3 nanocrystals are packaged by using the stable glass matrix, so that the problems that the Sn-based perovskite material is easy to oxidize in the environment and poor in stability are fundamentally solved; the material has good infrared acousto-optic comprehensive characteristics and an ultra-wide infrared transmission range, can be used as an acousto-optic medium to be applied to acousto-optic devices, and has a wide application prospect in the acousto-optic field.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of acousto-optic materials, in particular to a CsSnCl3 nanocrystal doped chalcogenide glass with excellent thermomechanical properties and its acousto-optic application. BACKGROUND

[0002] The acousto-optic effect was theoretically predicted by the French physicist Brillouin in the 1920s, and it was not until the advent of the laser that the research and application of acousto-optic devices were greatly promoted. Today, acousto-optic technology has gradually developed into an important branch of optoelectronics, and has important application value in the fields of laser communication, spectral analysis, optical fiber sensing, etc. Acousto-optic modulators based on the acousto-optic effect can control the deflection direction, intensity, frequency, etc. of the laser beam. Excellent acousto-optic medium materials need to have high acousto-optic figure of merit (M2 M 2 ), low ultrasonic attenuation coefficient (β2 α ) and high longitudinal wave speed (vL υ L ), as well as good thermomechanical properties.

[0003] Traditional acousto-optic materials, such as fused quartz (SiO2 M 2= 1.5 × 10 -18 s 3 / g) and tellurium dioxide crystal (TeO2 M 2= 34.5 × 10 -18 s 3 / g), have achieved commercial application, but these traditional acousto-optic materials are difficult to meet the demand for high diffraction efficiency. Chalcogenide glasses have high refractive index, ultra-wide infrared transmission range (1~20 μm) and significantly higher acousto-optic figure of merit (M2 M 2= 659 × 10 -18 s 3 / g) than traditional materials (such as As2Se3 glass), making them ideal candidate materials for infrared acousto-optic applications. However, the inherent defects of chalcogenide glasses limit their practical application: on the one hand, the relatively low longitudinal wave speed (vL Figure 1 L ) helps to improve M2 M 2, but it also leads to an increase in the ultrasonic attenuation coefficient (β2 α ), so a balance between the two needs to be considered; on the other hand, the relatively low thermomechanical properties and laser damage threshold of chalcogenide glasses, as well as the strong thermo-optic effect, make it difficult to meet the requirements for durability and stability in long-term device use, thus limiting the practical application of chalcogenide glasses in high-performance acousto-optic devices. Therefore, there is an urgent need to develop new infrared acousto-optic materials that combine excellent thermomechanical properties and acousto-optic properties. SUMMARY

[0004] The technical problems to be solved by the present application are to provide a CsSnCl3 nanocrystal doped chalcogenide glass and its acousto-optic application, which has excellent thermal mechanical properties and high robustness, outstanding comprehensive characteristics, can be applied to acousto-optic devices as an acousto-optic medium, and has a wide application prospect in the acousto-optic field.

[0005] The technical solution adopted by the present application to solve the above technical problems is: a CsSnCl3 nanocrystal doped chalcogenide glass, the molar composition formula of the chalcogenide glass is 97(0.8GeS2-0.2Sb2S3)-3CsSnCl3, and the chalcogenide glass is dispersed with CsSnCl3 nanocrystals in situ precipitated by heat treatment.

[0006] The present application realizes the in-situ precipitation of CsSnCl3 nanocrystals in the glass matrix by precisely controlling the heat treatment process. As preferred, the temperature of the heat treatment is 280-290 ℃, and the time is 8-10 h. As further preferred, the temperature of the heat treatment is 290 ℃, and the time is 10 h.

[0007] In a preferred embodiment, the preparation method of the chalcogenide glass is: first, a glass semi-product is prepared by a vacuum melting and quenching method, and then the glass semi-product is subjected to the heat treatment, so that the chalcogenide glass is obtained.

[0008] The average grain size of the CsSnCl3 nanocrystals is 23.5-39.2 nm.

[0009] The full transmittance wave band of the chalcogenide glass covers 0.7-12 μm, and the peak transmittance is 65-75 %.

[0010] The acousto-optic merit value of the chalcogenide glass at a wavelength of 1550 nm is M 2 is (100-112)×10 -18 s 3 The ultrasonic attenuation coefficient of the chalcogenide glass at 10 MHz is 0.89-3.68 dB / cm. α

[0011] The Vickers hardness of the chalcogenide glass is 179.7-197.6 kg / mm 2 , and the thermo-optic coefficient of the chalcogenide glass at a wavelength of 1550 nm is (17.8-24.0)×10 -6 K -1 .

[0012] The application of the above CsSnCl3 nanocrystal doped chalcogenide glass as an acousto-optic medium in acousto-optic devices.

[0013] Compared with the prior art, the present application has the following advantages: ​(1) The CsSnCl3 nanocrystal doped chalcogenide glass has excellent thermal mechanical properties and high robustness, and the comprehensive characteristics are outstanding, and the parameters such as Vickers hardness, elastic modulus, thermo-optic coefficient, laser damage threshold and the like are significantly improved compared with current mainstream acousto-optic chalcogenide glasses, which provides guarantee for stable operation of the device in high temperature and high power environment.

[0014] (2) The CsSnCl3 nanocrystal doped chalcogenide glass has the characteristics of environmental friendliness, and does not contain toxic elements such as Pb in the composition. At the same time, the chalcogenide glass encapsulates the CsSnCl3 nanocrystal by using a stable glass matrix, and fundamentally solves the problems of easy oxidation and poor stability of Sn-based perovskite materials in the environment.

[0015] (3) The CsSnCl3 nanocrystal doped chalcogenide glass has good infrared acousto-optic comprehensive characteristics. The present application realizes in-situ precipitation of CsSnCl3 nanocrystal in the glass matrix by accurately controlling the heat treatment process. The acousto-optic merit value of the sample after 290 DEG C heat treatment optimization is 100*10 M 2can be reached -18 s 3 α The ultrasonic attenuation coefficient at 10 MHz is as low as 0.89 dB / cm, which shows high acousto-optic effect and low sound wave propagation loss. The CsSnCl3 nanocrystal doped chalcogenide glass has an ultra-wide infrared transmission range, and is a high-performance infrared acousto-optic medium, which can be applied to acousto-optic devices as an acousto-optic medium, and has a wide application prospect in the field of acousto-optics. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 2 is the X-ray diffraction pattern of the sample of embodiment 1 to embodiment 4; Figure 3 is the infrared transmission spectrum of the sample of embodiment 1 to embodiment 4; Figure 4 is the refractive index dispersion diagram of the sample of embodiment 1 to embodiment 4; Figure 1 is the normalized acousto-optic parameter change schematic diagram of the sample of embodiment 1 to embodiment 4. DETAILED DESCRIPTION

[0017] The present application will be further described in detail below in combination with the embodiments of the drawings.

[0018] ​The present application provides four examples and three comparative examples to illustrate and compare the effect of the present application. Examples 1-4 are all chalcogenide glasses, and the molar composition formula of each is 97(0.8GeS2-0.2Sb2S3)-3CsSnCl3. Comparative examples 1-3 are GeSbS-CsCl glass ceramics, AsTeS3 glass, and As2S3 glass, respectively. The glass semi-finished products of examples 1-4 and comparative examples 1-3 are prepared by a vacuum melting and quenching method. Among them, example 1 is a glass semi-finished product and does not undergo subsequent heat treatment; the glass semi-finished products of examples 2-4 are each subjected to heat treatment, with heat treatment temperatures of 280°C, 290°C, and 300°C, respectively, and heat treatment times of 10 hours each; the glass semi-finished products of comparative examples 1-3 are also subjected to heat treatment, with heat treatment temperatures of 280°C, 290°C, and 300°C, respectively, and heat treatment times of 10 hours each.

[0019] The preparation method of the chalcogenide glass sample of example 2 includes the following steps: 1) According to the molar composition formula of the chalcogenide glass, accurately weigh the single-element raw materials and perovskite raw materials with a purity of 5N, mix the weighed raw materials uniformly, and then place them in a quartz ampoule; vacuumize the quartz tube to a vacuum degree of 10 -3 Pa, and then seal the quartz tube with a hydrogen-oxygen flame; 2) Place the sealed quartz tube in a rocking furnace and melt at 800-900°C for 10-12 hours; when the furnace temperature drops to 600-700°C, take the quartz tube out of the rocking furnace and quench it with compressed air until the glass melt surface separates from the inner wall of the quartz tube; 3) Place the quartz tube in an annealing furnace and anneal at a temperature 5-20°C lower than the glass transition temperature (Tg) of the glass for 8-10 hours to release internal stress of the glass; after annealing, take out the glass rod from the quartz tube to obtain a glass semi-finished product; T g 4) Cut the glass semi-finished product into a sheet shape, and then place it in an annealing furnace for heat treatment, with a heat treatment temperature of 280°C and a heat treatment time of 10 hours; 5) After heat treatment, polish the glass surface using a polishing pad and polishing liquid to obtain a sheet-shaped glass sample with parallel surfaces and a smooth surface for subsequent testing. 6) The glass sample is subjected to a transmittance test, a haze test, and a refractive index test.

[0020] The sample testing method and test results are as follows: I. Crystal phase characterization: The crystal phases of the samples of examples 1-4 are characterized by an X-ray diffractometer, and the X-ray diffraction patterns are as shown in Figure 1 FIG. 1. Figure 2It can be seen that the samples have obvious diffraction peaks at 22.6°, 32.0°, 39.5°, 46.0° and 51.7°, and are well aligned with the standard card No. 22-0200 CsSnCl3, indicating that CsSnCl3 perovskite crystal phase is precipitated. Example 4 shows other obvious diffraction peaks, which are shown to be GeS2 crystal phase by PDF card comparison. According to the Scherrer formula , the average grain size of the samples of Examples 1 to 4 is calculated to be 23.5 nm, 26.3 nm, 27.4 nm and 39.2 nm, respectively.

[0021] II. Optical property test: The infrared transmission spectra of Examples 1 to 4 were measured by a visible-near infrared spectrophotometer and a Fourier infrared spectrometer, and the infrared transmission spectra thereof are shown in Figure 2 It can be seen from dn / dT that the full transmission band of the samples of Examples 1 to 4 covers 0.7 to 12 μm, and the highest transmission rate is 65 to 75 %. The refractive index n and the thermo-optic coefficient Figure 3 of the samples of Examples 1 to 4 were measured by an infrared variable angle spectroscopic ellipsometer, and the refractive index dispersion diagram is shown in Figure 3 It can be seen from p that the samples of Examples 1 to 4 all show normal dispersion, and the refractive index increases with the increase of the heat treatment temperature. This can explain the decrease of the sample transmission rate in the infrared flat region of the transmission spectrum. According to the Fresnel formula, the greater the refractive index of the sample, the greater the interface refractive index difference, and the lower the transmission rate. The change of the refractive index after heat treatment can be explained according to the effective medium theory. Since the refractive index of the CsSnCl3 crystal is larger than that of the matrix glass, the further precipitation leads to the increase of the overall refractive index. In the early stage of nanocrystal growth, the specific surface area is large, and the interface polarization effect is significant; with the increase of the grain size, the relative contribution of the interface polarization is weakened, and the increase of the refractive index is mainly from the perovskite crystal phase itself with a higher refractive index.

[0022] III. Thermo-mechanical property test: The Vickers hardness Hν is characterized by an indentation microhardness tester, and the control parameters are 50 gf under load for 10 s. The relevant parameters required for calculating the elastic modulus include the longitudinal wave speed, the transverse wave speed and the density. The density of the sample is measured by the Archimedes drainage method pThe longitudinal wave speed and the transverse wave speed of the samples of Example 1 to Example 4 were measured by the pulse echo method and in reference to the standard GB / T 5266-2006. The glass transition temperature Tg of the samples of Example 1 to Example 4 was obtained by differential scanning calorimeter test. The laser damage threshold test was carried out by the S-on-1 damage probability method in reference to the national standard (GB / T 16601.2-2017). The glass samples were irradiated by laser with a wavelength of 1550 nm, a repetition frequency of 5 KHz, and a pulse width of 20 ns for 1 second at different energy densities. At least 10 points were irradiated at each laser energy density, and the corresponding damage probability was obtained. The corresponding positions in the coordinate system of laser energy density and damage probability were recorded, and then linear fitting was performed on these probabilities. The intersection of the straight line with the energy axis was the zero-probability damage threshold, i.e. the laser damage threshold of the glass sample.

[0023] The mechanical properties of the samples of Example 1 to Example 4 obtained by the test are shown in Table 1, and the thermal parameters and laser damage thresholds are shown in Table 2.

[0024] Table 1: Mechanical properties of the samples of Example 1 to Example 4

[0025] Table 2: Thermal parameters and laser damage thresholds of the samples of Example 1 to Example 4

[0026] Four, acousto-optic property test: The acousto-optic property includes the acousto-optic merit M 2 and the ultrasonic attenuation coefficient α . The acousto-optic merit M 2 is calculated by using the relevant parameters including the refractive index n , the photoelastic coefficient p 12 , the density υ and the longitudinal wave speed υ L . The photoelastic coefficient p 12 of the sample at a wavelength of 1550 nm was measured by the Mach-Zehnder interference method and in reference to the standard BS 7604-1-1992.

[0027] The longitudinal wave speed dn / dT L and the ultrasonic attenuation coefficient α, the pulse signal is transmitted and received by the pulse emission receiver and the ultrasonic probe with a center frequency of 10 MHz, the longitudinal wave speed is calculated according to the time difference between the adjacent main peak and the secondary peak of the echo on the oscilloscope; the ultrasonic attenuation coefficient is measured according to the amplitude difference between the adjacent main peak and the secondary peak of the echo on the oscilloscope α .

[0028] The acousto-optic merit value of the samples of examples 1-4 is calculated by formula (1) M 2: , The acousto-optic properties of the samples of examples 1-4 obtained by testing are shown in table 3, and the comprehensive properties of the samples of examples 1-4 and comparative examples 1-3 are compared in table 4.

[0029] Table 3: Acousto-optic properties of samples of examples 1-4

[0030] Table 4: Comparison of comprehensive properties of samples of examples 1-4 and comparative examples 1-3

[0031] The parameters of the samples of examples 1-4 and comparative examples 1-3 are as described above. As can be seen from the table, as the heat treatment temperature increases, the elastic modulus of the sample increases, indicating that the interatomic bonding strength is stronger, that is, the average bond energy is greater, and the glass network structure is more rigid. The reason is that the halogen element as a glass modifier gradually precipitates to form small-size crystals that are dispersed and densely bonded as high-rigidity phases. The change trend of hardness is roughly consistent with that of elastic modulus, because the hardness of the crystal phase is higher than that of the glass phase, and the volume fraction of the crystal phase increases, which can improve the overall hardness. However, the microhardness and elastic modulus of example 4 decrease because the GeS2 crystal phase precipitates and the grain size is relatively large, the hindering effect of the grain boundary on dislocations is weakened, and the thermal expansion mismatch of the crystal-glass interface, interface defects and pores can cause residual stress and become crack initiation sites.

[0032] Thermal-optical coefficient dn / dT reflects the thermal stability of the sample, Figure 4 The smaller the absolute value of the thermal-optical coefficient, the less the material is affected by the possible thermal effects in practical applications, that is, the better the thermal stability. Since the metal halide perovskite has a negative thermal-optical coefficient, it can harmonize with the positive thermal-optical coefficient of the matrix glass, so that the absolute value of the overall thermal-optical coefficient of the composite material decreases with the precipitation of the perovskite crystal, and the overall thermal-optical coefficient is relatively small. At the same time, the thermal conductivity of the crystal phase is high, which is beneficial to heat diffusion, and under the synergistic action of the two, the thermal lens effect can be effectively suppressed.

[0033] For example 4, the precipitation of GeS2 crystal phase plays a role in inhibiting thermal expansion, thus increasing the thermo-optic coefficient. The laser damage resistance is also a key factor of material performance, which is related to factors such as glass transition temperature T g , hardness Hν, thermal conductivity, etc. The thermal conductivity of the crystal phase is higher, which is conducive to heat diffusion, so the precipitation of nanocrystals contributes to the improvement of the laser damage threshold (LIDT) in many ways, and too large crystal grains (example 4) will exacerbate optical inhomogeneity, leading to local light intensity enhancement and more internal defects, thus reducing the LIDT.

[0034] The normalized acousto-optic parameter changes of the samples of examples 1-4 are shown in Figure 4 . As can be seen from υ , the ultrasonic attenuation coefficient α decreases from 1.23 dB / cm to 0.89 dB / cm at 10 MHz. Ultrasonic attenuation is due to Akhieser loss caused by the relaxation of thermal phonon distribution in the equilibrium direction. When the ultrasonic wave propagates inside the glass, it will cause the vibration of the atoms and structural units inside the glass. The vibration amplitude is determined by the type of structural unit and the connectivity of the glass network. The heat treatment crystallization promotes the rearrangement of the glass network structure, leading to an increase in the elastic modulus, which indicates that the network structure of the residual glass matrix becomes more rigid, which helps to increase the sound speed and reduce the ultrasonic attenuation. The larger M 2 change of the sample of example 4 is caused by the increase of its n and the decrease of the longitudinal wave sound speed υ L . Due to the strong scattering of sound waves in the medium with larger crystal grains, the ultrasonic wave energy is dispersed on the crystal phase interface, and the α of the sample of example 4 increases significantly, which is more obvious at high frequency ultrasonic waves. In the perovskite nanocrystal-doped chalcogenide glass system, both the network structure rigidity and the sound wave scattering affect the ultrasonic attenuation. Overall, the sample of example 3 shows the best acousto-optic performance, with a α decrease of 27.7 %, ​ L an increase of 3.3 %, while M 2 only decreases by 0.8 %, and it also shows the best thermal mechanical performance.

[0035] There is an optimal crystal size distribution for the thermal mechanical performance of the composite material, and a proper heat treatment route helps to improve the robustness of the acousto-optic medium in practical applications. Overall, the sample of example 3 has the best comprehensive characteristics, which is significantly improved compared to other samples, and has the potential to be used as a medium material for high-performance acousto-optic devices, and also provides a new idea and method for the development of high-performance infrared acousto-optic materials.

Claims

1. A CsSnCl3 nanocrystal-doped chalcogenide glass, characterized by, The molar composition formula of the chalcogenide glass is 97(0.8GeS2-0.2Sb2S3)-3CsSnCl3, and the chalcogenide glass is dispersed with CsSnCl3 nanocrystals in-situ precipitated by heat treatment.

2. The CsSnCl3 nanocrystal doped chalcogenide glass according to claim 1, wherein, The temperature of the heat treatment is 280-290 ℃, and the time is 8-10 h.

3. The CsSnCl3 nanocrystal doped chalcogenide glass according to claim 2, wherein, The temperature of the heat treatment is 290 ℃, and the time is 10 h.

4. The CsSnCl3 nanocrystal-doped chalcogenide glass according to claim 1, wherein The preparation method of the chalcogenide glass is: first, a glass semi-product is prepared by a vacuum melting and quenching method, and then the glass semi-product is subjected to the heat treatment, so that the chalcogenide glass is obtained.

5. The CsSnCl3 nanocrystal doped chalcogenide glass according to claim 1, wherein, The average grain size of the CsSnCl3 nanocrystals is 23.5-39.2 nm.

6. The CsSnCl3 nanocrystal doped chalcogenide glass according to claim 1, wherein, The full transmittance wave band of the chalcogenide glass covers 0.7-12 μm, and the peak transmittance is 65-75 %.

7. The CsSnCl3 nanocrystal doped chalcogenide glass according to claim 1, wherein, The acousto-optic figure of merit of the chalcogenide glass at a wavelength of 1550 nm M 2 is (100~112) x 10 -18 s 3 The ultrasonic attenuation coefficient at 10 MHz α is 0.89~3.68 dB / cm.

8. The CsSnCl3 nanocrystal doped chalcogenide glass according to claim 1, wherein, The Vickers hardness of the chalcogenide glass is 179.7~197.6 kg / mm 2 , and the thermo-optic coefficient thereof at a wavelength of 1550 nm is (17.8~24.0)×10 -6 K -1 .

9. Application of the CsSnCl3 nanocrystal-doped chalcogenide glass in an acousto-optic device as an acousto-optic medium according to any one of claims 1-8.

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