Temperature measurement method for thermogravimetric analysis of silicon carbide crystal based on dual irradiation of Si < + > ions and neutrons

Abstract

The invention relates to the technical field of temperature measurement of crystal materials, and relates to a temperature measurement method for SiC crystal thermogravimetric analysis based on Si < + > ion and neutron dual irradiation, and the method specifically comprises the following steps: S1, dual irradiation of a SiC crystal; s2, annealing treatment; s3, carrying out thermogravimetric test; s4, processing thermogravimetric test data; s5, measuring the temperature of the environment to be measured; the expression form of the temperature calibration equation obtained in the step S4 is b = alpha + beta T * + gamma T * 2 + delta T *; according to the temperature measurement method for thermogravimetric analysis of the Si < + > ion and neutron dual-irradiation SiC crystal, the internal structure of the SiC crystal is changed by performing annealing treatment on the SiC crystal at different temperatures, thermogravimetric testing is performed on the SiC crystal subjected to annealing treatment at different temperatures, data are analyzed, a polynomial equation is established, and the extremely high environment temperature can be effectively tested; and the method has relatively high accuracy.

Description

Technical Field

[0001] The present invention belongs to the technical field of temperature measurement of crystal materials, and in particular relates to a temperature measurement method based on thermogravimetric analysis of silicon carbide crystals irradiated by Si+ ions and neutrons. Background Art

[0002] Accurately measuring temperature in high-temperature and high-radiation environments is crucial in fields such as aerospace, nuclear energy, and extreme industrial applications. However, traditional temperature measurement methods, such as thermocouples and RTDs, are susceptible to interference from factors such as high temperature and radiation under extreme conditions, resulting in reduced measurement accuracy or even failure. Therefore, developing new temperature measurement methods that can maintain stability and high accuracy in extreme environments has become a key research area.

[0003] Silicon carbide (SiC), as a material with excellent high temperature resistance and radiation resistance, has become an ideal candidate material for temperature measurement and other critical applications in high temperature and high radiation environments. However, direct use of SiC for temperature measurement still faces a series of challenges, including how to accurately calibrate the temperature and how to reduce measurement errors caused by environmental factors. In order to overcome these technical difficulties, the present invention proposes a method based on SiC. + An innovative temperature measurement method using dual ion and neutron irradiation to treat SiC crystals and combining it with thermogravimetric analysis technology.

[0004] Conventional temperature calibration models are mainly based on traditional linear equations. Due to the possible phase change and defect recombination of materials in high-temperature environments, the linear equations are inconsistent with the actual test results. Therefore, there is an urgent need for a temperature measurement method that can adapt to high-temperature test environments and has a certain degree of accuracy. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a Si-based + A temperature measurement method for thermogravimetric analysis of silicon carbide crystals irradiated with ions and neutrons. This method performs double irradiation on the SiC crystal, inducing changes in its internal microstructure. The temperature changes are then monitored using thermogravimetric analysis technology. A temperature calibration equation is established through fitting analysis of the thermogravimetric data, thereby achieving high-precision temperature measurement in extreme environments.

[0006] The present invention is based on Si + The temperature measurement method for thermogravimetric analysis of SiC crystals irradiated with ions and neutrons is characterized by the following specific implementation steps:

[0007] S1. Double irradiation of SiC crystal: SiC crystal is Si + irradiation and neutron irradiation;

[0008] S2, annealing treatment: the 6H-SiC crystal after the double irradiation in step S1 is annealed at a constant gradient temperature T * Annealing treatment is performed under

[0009] S3, thermogravimetric test: step S2 is carried out at the annealing temperature T * The 6H-SiC crystals treated below were subjected to thermogravimetric testing one by one;

[0010] S4. Processing the thermogravimetric test data: The heating temperature T during the thermogravimetric test and the corresponding relative mass change Δ of the 6H-SiC crystal are compared with the annealing temperature T. * The data were sorted to obtain the temperature calibration equation, and the annealing temperature T * As the independent variable and the fitting parameter b as the dependent variable, the temperature calibration equation b=α+βT is constructed. * +γT *2 +δT *3 , and determine the values ​​of the parameters in the polynomial equation;

[0011] S5. Determine the ambient temperature to be measured: Anneal the double-irradiated 6H-SiC crystal in the test environment, then remove the annealed crystal for thermogravimetric testing to obtain a Δ-T equation, analyze the slope b0 of the Δ-T equation at the test ambient temperature, and obtain the corresponding annealing temperature T* by inversely calculating the temperature calibration equation in step S4. The annealing temperature T* is then the test ambient temperature.

[0012] Preferably, in the process of constructing the polynomial equation in step S4, a Δ-T equation fitting step is also included, and the relative mass change Δ of the 6H-SiC crystal is calculated based on the thermogravimetric data obtained from the 6H-SiC crystal at different annealing temperatures, and a linear equation Δ=a+bT of the relative mass change of the 6H-SiC crystal at different annealing temperatures and the temperature during the thermogravimetric process is obtained by fitting.

[0013] Preferably, in the thermogravimetric test process of step S3, nitrogen gas should be steadily introduced at a flow rate of 15 to 50 mL / min to form the nitrogen environment required for the thermogravimetric test, the heating rate of the thermogravimetric test should be 5 to 10°C / min, the temperature range of the thermogravimetric test should be 25 to 1400°C, and the mass measurement accuracy should be ≤0.1 μg; before the start of the thermogravimetric test, the empty crucible baseline correction should be repeated more than 3 times to obtain the average value, and the average value of the obtained empty crucible data should be used as the baseline of the TG data.

[0014] Preferably, step S1 includes the following sub-steps:

[0015] S11、Si + Irradiation treatment: The SiC crystal is subjected to single-energy Si + ion irradiation;

[0016] S12, neutron irradiation: Si + The irradiated SiC crystal is then subjected to neutron irradiation.

[0017] Preferably, the 6H-SiC crystal selected in step S1 is a nitrogen-doped 6H-SiC crystal, and the nitrogen-doping concentration of the 6H-SiC crystal is 1×10 20 ~5×10 20 cm -3 , Si + +1 valence Si selected during irradiation + Ions are irradiated ions, Si + The ion energy range is 0.1-1.0 MeV, Si + Total irradiation dose ≥10 16 cm -2 The irradiation temperature is controlled at 25±5℃, the irradiation direction is along the c-axis of the SiC crystal axis, and the crystal axis direction offset is ≤4°.

[0018] Preferably, before the annealing treatment, the 6H-SiC crystal after neutron irradiation in step S2 is divided into crystals with a mass of 5-10 mg, 4-6 divided SiC crystals are selected at different annealing temperatures and rapidly heated, the cut SiC crystals are heated from room temperature to the target temperature, the heating time is ≤4 minutes and the temperature is kept warm, and the temperature is cooled to room temperature after the temperature is kept warm; wherein, the cut small SiC crystals are selected and the mass is recorded as M, the annealing temperature T * 1000-1700℃, at annealing temperature T * The holding time is ≥10min and the cooling rate is ≤20℃ / min.

[0019] Preferably, in step S2, the fast neutron irradiation is performed at a neutron flux of ≥1×10 14 n / (cm 2 ·s) under the condition of irradiation, and graphite moderator was used to control the energy spectrum distribution during the irradiation process. The neutron energy E>0.1MeV and the irradiation dose was 1×10 18 ~5×10 19 cm -2 , irradiation temperature ≤300℃.

[0020] Preferably, in step S5 , the relative mass change of the 6H—SiC crystal is Δ=(mM) / M×100%, and the linear fitting of the Δ-T equation adopts a weighted least squares method, with the weight coefficient being inversely proportional to the temperature measurement error.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. The present invention is based on Si+ The temperature measurement method for thermogravimetric analysis of silicon carbide crystals irradiated with ions and neutrons solves the problem of traditional linear models in which test results are affected by phase changes and defect recombination of materials in high-temperature environments by establishing a new temperature calibration model. By performing thermogravimetric tests on SiC crystals annealed in the test environment to obtain given constraints, the constraints are brought into the analysis with the established calibration equation model to determine the exact temperature of the test environment.

[0023] 2. The present invention is based on Si + Temperature measurement method for thermogravimetric analysis of silicon carbide crystals irradiated by ions and neutrons + Ion irradiation and fast neutron irradiation synergistically control the defect density of SiC crystals. The synergistic effect of the two results in a gradient distribution of defect density from the surface to the bulk, avoiding excessive amorphization caused by single irradiation. The interaction between defects forms a stable defect network, significantly improving the signal-to-noise ratio of the thermogravimetric signal. In addition, the defect network induced by dual irradiation exhibits dynamic response characteristics to temperature changes, significantly improving the temperature response sensitivity.

[0024] 3. The present invention is based on Si + The temperature measurement method for thermogravimetric analysis of silicon carbide crystals irradiated with ions and neutrons has a calibration equation that produces significant nonlinear deviations in the high-temperature range due to complex processes such as material phase transition and defect recombination compared to traditional linear models. The temperature calibration equation of the present invention (b = α + βT * +γT * 2+δT * 3) Dynamic compensation is achieved by fitting thermogravimetric data. When the measurement temperature is in the high temperature range of 1500-1700℃, the quadratic term (γT * 2) It can characterize the quality transition caused by stacking fault repair, the cubic term (δT * 3) corresponds to the recrystallization effect of the amorphous region. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The thermogravimetric test data distribution and fitting curve of the SiC crystal after double irradiation in the test method of the present invention;

[0026] Figure 2 The thermogravimetric test data distribution and fitting curve of the SiC crystal after annealing at an annealing temperature of 1100° C. in the test method of the present invention;

[0027] Figure 3 The thermogravimetric test data distribution and fitting curve of the SiC crystal after annealing at an annealing temperature of 1200° C. in the test method of the present invention;

[0028] Figure 4The thermogravimetric test data distribution and fitting curve of the SiC crystal after annealing at an annealing temperature of 1300° C. in the test method of the present invention;

[0029] Figure 5 The thermogravimetric test data distribution and fitting curve of the SiC crystal after annealing at an annealing temperature of 1400° C. in the test method of the present invention;

[0030] Figure 6 The thermogravimetric test data distribution and fitting curve of the SiC crystal after annealing at an annealing temperature of 1500° C. in the test method of the present invention;

[0031] Figure 7 The thermogravimetric test data distribution and fitting curve of the SiC crystal after annealing at an annealing temperature of 1600° C. in the test method of the present invention;

[0032] Figure 8 The thermogravimetric test data distribution and fitting curve of the SiC crystal after annealing at an annealing temperature of 1700° C. in the test method of the present invention;

[0033] Figure 9 The thermogravimetric test data distribution and fitting curve set of SiC crystals without annealing and SiC crystals annealed at different annealing temperatures;

[0034] Figure 10 The fitting temperature calibration curve b==α+βT of the test method of the present invention * +γT *2 +δT *3 ;

[0035] Figure 11 Flowchart of the testing method of the present invention. DETAILED DESCRIPTION

[0036] To fully describe the technical content, objectives and effects of the present invention, the following will be described in detail with reference to the accompanying drawings.

[0037] The present invention is based on Si + Temperature measurement method for thermogravimetric analysis of silicon carbide crystals irradiated with ions and neutrons, such as Figure 11 As shown, the specific steps include:

[0038] S1. Double irradiation of SiC crystal: SiC crystal is Si + irradiation and neutron irradiation;

[0039] S11、Si + Irradiation treatment: SiC crystal is irradiated along the crystal axis c-axis direction +ion irradiation;

[0040] S12, neutron irradiation: Si + The irradiated SiC crystal is subjected to neutron irradiation;

[0041] In step S1, nitrogen-doped 6H-SiC crystals with a larger lattice constant should be selected. The interlayer spacing of SiC crystals with a larger lattice constant is looser, which is more conducive to the migration of carriers. Compared with SiC crystals with a medium lattice constant, they are more suitable for high temperature and high pressure environments. The nitrogen doping concentration of 6H-SiC crystals is 1×10 20 ~5×10 20 cm -3 ; Nitrogen doping in 6H-SiC crystals helps to enrich the types of irradiation defects in 6H-SiC crystals and can improve the sensitivity of thermogravimetric analysis.

[0042] Furthermore, the Si of step S11 + The irradiation ions selected during the irradiation process are +1 valence Si + ions, Si + The ion energy range is 0.1-1.0 MeV, and the total irradiation dose is ≥10 16 cm -2 The irradiation temperature is 25±5℃, the irradiation direction is along the z-axis of the SiC crystal axis, the crystal axis direction offset is ≤4°, Si + The main effect of irradiation is to + Irradiation causes the displacement of shallow surface atoms in SiC crystals, generating point defects such as vacancies and interstitial atoms or forming tiny dislocation rings, which leads to more defects and creates favorable conditions for subsequent neutron irradiation and annealing treatments.

[0043] In addition, the neutron irradiation in step S12 is carried out by fast neutron irradiation and the neutron flux is ≥1×10 14 n / (cm 2 ·s). The irradiation process uses a graphite moderator to control the energy spectrum distribution. The irradiation neutron energy E>0.1MeV, the irradiation dose is 1×1018 to 5×1019cm-2, and the irradiation temperature is ≤300°C. Fast neutron irradiation can improve the radiation resistance of SiC crystals, making them more suitable for high-radiation testing environments. Neutron irradiation causes the crystal to form deep defect clusters such as stacking faults and amorphized regions through high-energy cascade collisions. These defects generated within the crystal can affect the original thermal expansion coefficient of the crystal. TGA can generally indirectly reflect changes in the thermal stability of the material. Therefore, neutron irradiation can improve the sensitivity of subsequent thermogravimetric testing. Double irradiation can induce the defect network in SiC crystals to respond dynamically to temperature changes.

[0044] S2, annealing treatment: set up experimental groups with gradient changes in annealing temperature, and in each experimental group, anneal the SiC crystal after double irradiation in step S1 at the annealing temperature T* of the experimental group, wherein the annealing temperature T * The starting temperature is 1000℃, the constant gradient temperature range is 50-100℃, and the maximum annealing temperature does not exceed 1700℃;

[0045] Specifically, the double irradiated SiC crystal was split into crystals with a mass of 5-10 mg and annealed at each annealing temperature T * Randomly select 4-6 split SiC crystals and use rapid heating technology to raise the annealing temperature of the split SiC crystals from room temperature for ≤4min. Then, at the annealing temperature T * Keep warm for a certain time, and at each annealing temperature T * The temperature was kept at 10 min and then cooled to room temperature at a cooling rate of 20 °C / min.

[0046] Furthermore, the annealing temperature T in step S2 is * The temperature range is 1000-1700℃. The target annealing temperature of the experimental group is set at a fixed temperature interval within the temperature range. The number of experimental groups is selected according to actual needs. More than or equal to 7 annealing temperatures are tested. During the annealing process, when the annealing temperature does not exceed 1500℃, Si + Shallow point defects generated by irradiation preferentially reorganize and release energy, which is manifested as the initial mass change of the thermogravimetric curve. Deep defects such as stacking faults generated by fast neutron irradiation are gradually repaired by atomic diffusion in the high temperature range above 1500℃, resulting in secondary mass transition. The staged mass change makes the correlation coefficient between the thermogravimetric signal and temperature (R 2 ) is increased to ≥0.95, so when the SiC crystal is annealed, the quality will be lost to varying degrees. The mass of the SiC crystal before annealing is recorded as M, and the annealing temperature is recorded as T * .

[0047] S3, thermogravimetric test: Step S2 is carried out at different annealing temperatures T * The 6H-SiC crystals treated below were subjected to thermogravimetric testing one by one;

[0048] The annealed 6H-SiC crystals of each experimental group in step S2 were subjected to thermogravimetric analysis. The test temperature range of the thermogravimetric test was room temperature to 1400°C, the heating rate was 5-10°C / min, and nitrogen was kept flowing throughout the test at a nitrogen flow rate of 15-50 mL / min. The accuracy of the mass measurement during the thermogravimetric test was not higher than 0.1 μg. The mass of the 6H-SiC crystal during the thermogravimetric test was recorded as m, and the heating temperature during the thermogravimetric test was recorded as T.

[0049] Furthermore, the crucible used for the thermogravimetric test in step S3 is a high-purity alumina crucible with a purity of 99.99%. The high-purity alumina crucible can reduce the interference of impurities during the test. Before the start of the thermogravimetric test, the empty crucible needs to be calibrated for the empty crucible baseline. The empty crucible baseline calibration needs to be performed ≥3 times, and the average value of the repeated tests is taken to eliminate the influence of the quality of the crucible on the test results. The average value of the repeated tests is used as the baseline of the thermogravimetric test data of the empty crucible data. The thermogravimetric test needs to be carried out in a stable nitrogen environment. Maintaining a stable nitrogen supply during the test can prevent the oxidation of the SiC crystal, thereby affecting the quality detection of the experimental group samples after the thermogravimetric test. The flow rate of nitrogen during the thermogravimetric test is 15-50 mL / min, the heating rate of the thermogravimetric test is 5-10°C / min, the temperature range of the thermogravimetric test is 25-1400°C, and the mass measurement accuracy is ≤0.1μg.

[0050] S4. Processing the thermogravimetric test data: Fitting the heating temperature T and the corresponding relative mass change Δ of 6H-SiC crystal during the thermogravimetric test of the experimental group, and comparing the slope of Δ and T with the annealing temperature T * The temperature calibration equation is obtained by sorting the data.

[0051] S41, fitting a Δ-T equation: calculating the relative mass change Δ of the 6H-SiC crystal based on the thermogravimetric data obtained at different annealing temperatures, and obtaining a linear equation Δ=a+bT of the relative mass change of the 6H-SiC crystal at different annealing temperatures and the temperature during the thermogravimetric process;

[0052] The relative mass change of 6H-SiC crystal in the experimental group is Δ = (mM) / M × 100%. The mass change Δ of each experimental group is fitted with the heating temperature T during the thermogravimetric test using the weighted least squares method to obtain the Δ-T equation. The weight coefficient is inversely proportional to the temperature measurement error. The goodness of fit R 2 ≥0.95.

[0053] S42, establish temperature calibration equation: take annealing temperature T * As the independent variable and the fitting parameter b as the dependent variable, construct the polynomial equation b=α+βT * +γT *2 +δT *3 , and determine the values ​​of the parameters in the polynomial equation;

[0054] The values ​​of the parameters in the calibration equation are: α≈-138.22, β≈0.3138, γ≈-2.373E-4, and δ≈-6.177E-8. The calibration equation is valid for temperatures between 1000°C and 1700°C, with a residual error of ≤±2%. When the annealing temperature is within the high temperature range of 1500-1700°C, the crystal quality changes rapidly due to stacking fault repair induced by the high temperature. This is characterized by the quadratic term in the calibration equation. The recrystallization effect in the amorphous region causes a rapid change in crystal quality, corresponding to the cubic term in the calibration equation. Traditional linear equations, based on thermogravimetric measurements of 6H-SiC crystals, establish fitting equations based on the temperature of the thermogravimetric weight loss peak and the ambient temperature under test. However, at high temperatures, the temperature of the crystal's maximum weight loss peak exhibits irregular variations, making the fitting equation incompatible with the ambient temperature under test. The aforementioned high-temperature environment refers to a temperature range of 1500-1700°C for the test environment, and the low-temperature environment refers to a temperature range of 1000-1500°C for the test environment. However, the fitting data of the calibration equation of the present invention is due to the analysis of the significant difference in mass loss of 6H-SiC crystals in low-temperature and high-temperature environments. The thermogravimetric test data of 6H-SiC crystals after insulation in low-temperature and high-temperature environments are used as the basic data for the proposed equation for secondary analysis. By taking the different changes in defects in 6H-SiC crystals in high-temperature and low-temperature environments as the original intention of establishing the calibration equation, a temperature calibration equation covering both high-temperature and low-temperature environments is established.

[0055] S5. Determine the ambient temperature to be measured: anneal the double-irradiated 6H-SiC crystal in the environment to be measured, then take out the annealed crystal for thermogravimetric testing to obtain a Δ-T equation, analyze the slope b0 of the Δ-T equation at this temperature, and obtain the corresponding annealing temperature T* by inversely calculating the temperature calibration equation. The temperature value of T* is the ambient temperature to be measured.

[0056] The temperature measurement method based on the thermogravimetric analysis of silicon carbide crystals irradiated with Si+ ions and neutrons according to the present invention is further described below with reference to the following examples:

[0057] S1. Double irradiation of SiC crystal: SiC crystal is Si + irradiation and neutron irradiation;

[0058] S11、Si + Irradiation treatment: select nitrogen doping concentration of 2×10 20 cm -3 6H-SiC crystal, along the crystal axis z-axis direction single energy Si + Ion irradiation, the deviation angle of the irradiation direction is less than or equal to ±4°, Si +The ion energy of the irradiation was 0.5 MeV, and the total irradiation dose was 1×10 16 cm -2 , irradiation temperature is 25℃;

[0059] S12, neutron irradiation: Si + The 6H-SiC crystal after irradiation was irradiated with neutrons. The energy E of neutron irradiation was 0.2 MeV and the irradiation dose was 1.0×10 18 cm -2 , the irradiation temperature is 300℃, and the double irradiated SiC crystal is obtained;

[0060] S2, annealing treatment: set up 7 experimental groups with a temperature change range of 100℃, and the annealing temperatures of the 7 experimental groups are T1 * =1100℃、T2 * =1200℃、T3 * =1300℃、T4 * =1400℃、T5 * =1500℃、T6 * =1600℃ and T7 * =1700℃, the double irradiated SiC crystals were split into 5 mg crystals, 4 cut crystals were randomly selected from each experimental group as experimental samples, and the cut SiC crystals were heated from room temperature to the target annealing temperature of the current experimental group using the rapid heating technology. The heating time was 4 min, and then the experimental samples of the 7 experimental groups were annealed at the target annealing temperature T * The temperature was kept at 20 min, and then cooled to room temperature at a rate of 15 ° C / min; wherein, the annealing temperature T1 * =1100℃, the SiC crystal mass before annealing is M1, and the annealing temperature is T2 * =1200℃, the SiC crystal mass before annealing is M2, and the annealing temperature is T3 * =1300℃, the SiC crystal quality before annealing is M3, and the annealing temperature is T4 * =1400℃ in the experimental group, the quality of the SiC crystal before annealing was M4, and the annealing temperature was T5 * =1500℃ in the experimental group, the quality of the SiC crystal before annealing was M5, and the annealing temperature was T6 * =1600℃ in the experimental group, the quality of the SiC crystal before annealing was M6, and the annealing temperature was T7 * The crystal quality of the SiC crystal in the experimental group with a temperature of 1700° C. before annealing was M7.

[0061] S3, thermogravimetric test: The 6H-SiC crystals annealed in the seven experimental groups in step S2 were subjected to thermogravimetric test one by one; the heating temperature T of the thermogravimetric test ranged from room temperature to 1400°C, with a heating rate of 5°C / min. During the test, nitrogen was introduced at a flow rate of 30 mL / min throughout the test. * =1100 ℃ annealing treatment of 6H-SiC crystals were subjected to thermogravimetric testing, the mass of the 6H-SiC crystal corresponding to the heating temperature T in the thermogravimetric test was recorded as m1, the relative mass change of the 6H-SiC crystal Δ1 = (m1-M1) / M1×100%; the relative mass change of the 6H-SiC crystal at the annealing temperature T2 was recorded as m1. * =1200 ℃ annealing treatment of 6H-SiC crystals were subjected to thermogravimetric testing, the mass of the 6H-SiC crystal corresponding to the heating temperature T in the thermogravimetric test was recorded as m2, the relative mass change of the 6H-SiC crystal Δ2 = (m2-M2) / M2×100%; the relative mass change of the 6H-SiC crystal at the annealing temperature T3 was recorded as m2. * =1300 ℃ annealing treatment of 6H-SiC crystals were subjected to thermogravimetric testing, the mass of the 6H-SiC crystal corresponding to the heating temperature T in the thermogravimetric testing was recorded as m3, the relative mass change of the 6H-SiC crystal Δ3 = (m3-M3) / M3 × 100%; the relative mass change of the 6H-SiC crystal at the annealing temperature T4 was recorded as m3. * =1400 ℃ annealing treatment of 6H-SiC crystals were subjected to thermogravimetric testing, the mass of the 6H-SiC crystal corresponding to the heating temperature T in the thermogravimetric test was recorded as m4, the relative mass change of the 6H-SiC crystal Δ4 = (m4-M4) / M4×100%; the relative mass change of the 6H-SiC crystal at the annealing temperature T5 was recorded as m4. * =1500 ℃ annealing treatment of 6H-SiC crystals were subjected to thermogravimetric testing, the mass of the 6H-SiC crystal corresponding to the heating temperature T in the thermogravimetric testing was recorded as m5, the relative mass change Δ5 of the 6H-SiC crystal was equal to (m5-M5) / M5×100%; the relative mass change of the 6H-SiC crystal at the annealing temperature T6 was recorded as m5. * =1600 ℃ annealing treatment of 6H-SiC crystals were subjected to thermogravimetric testing, the mass of the 6H-SiC crystal corresponding to the heating temperature T in the thermogravimetric testing was recorded as m6, the relative mass change of the 6H-SiC crystal Δ6 = (m6-M6) / M6×100%; the relative mass change of the 6H-SiC crystal at the annealing temperature T7 was recorded as m6. * = 1700 ° C annealing treatment of 6H-SiC crystal was subjected to thermogravimetric testing, the mass of the 6H-SiC crystal corresponding to the heating temperature T in the thermogravimetric test was recorded as m7, and the relative mass change of the 6H-SiC crystal was Δ7 = (m7-M7) / M7×100%.

[0062] S4. Processing the thermogravimetric test data: Fitting the heating temperature T and the corresponding relative mass change Δ of 6H-SiC crystal during the thermogravimetric test, and comparing the slope of Δ and T with the annealing temperature T * The temperature calibration equation is obtained by sorting the data.

[0063] S41, fitting Δ-T equation: Figure 9 As shown, the thermogravimetric data of the seven experimental groups in step S2 are summarized, and the relative mass change Δ of the 6H-SiC crystal obtained from the seven experimental groups is calculated respectively. The linear equation Δ=a+bT of the relative mass change of the 6H-SiC crystal at different annealing temperatures and the temperature during the thermogravimetric process is obtained by least square fitting.

[0064] like Figure 2 As shown, the annealing temperature T1 * =1100℃ TG data of 6H-SiC crystal in the experimental group during the thermogravimetric test and the fitting curve of relative mass change Δ and annealing temperature T, where Δ1 = (m1-M1) / M1×100%. Combined with Table 1, it can be seen that the linear equation Δ1 = a1 + b1T fitted by the least squares method is 0.034, b1 is 0.076×10 -4 .

[0065]

[0066]

[0067] Table 1 Parameters a and b in the Δ-T equation obtained from thermogravimetric testing of silicon carbide crystals after gradient annealing temperature treatment

[0068] and the goodness of fit R 2 Value

[0069] like Figure 3 As shown, the annealing temperature T2 * =1200℃ TG data of 6H-SiC crystal in the experimental group during the thermogravimetric test and the fitting curve of relative mass change Δ and annealing temperature T, where Δ2 = (m2-M2) / M2×100%. Combined with Table 1, it can be seen that the linear equation Δ2 = a2+b2T fitted by the least squares method is 0.004, b2 is 2.133×10 -4 .

[0070] like Figure 4 As shown, annealing temperature T3 *=1300℃ TG data of 6H-SiC crystal in the experimental group during the thermogravimetric test and the fitting curve of relative mass change Δ and annealing temperature T, where Δ3 = (m3-M3) / M3×100%. Combined with Table 1, it can be seen that the linear equation Δ3 = a3 + b3T fitted by the least squares method is -0.043, b3 is 2.919×10 -4 .

[0071] like Figure 5 As shown, annealing temperature T4 * =1400℃ TG data of 6H-SiC crystal in the experimental group during the thermogravimetric test and the fitting curve of relative mass change Δ and annealing temperature T, where Δ4 = (m4-M4) / M4×100%. Combined with Table 1, it can be seen that the linear equation Δ4 = a4 + b4T fitted by the least squares method is 0.043, b4 is 4.069×10 -4 .

[0072] like Figure 6 As shown, annealing temperature T5 * =1500℃ TG data of 6H-SiC crystal in the experimental group during the thermogravimetric test and the fitting curve of relative mass change Δ and annealing temperature T, where Δ5 = (m5-M5) / M5×100%. Combined with Table 1, it can be seen that the linear equation Δ5 = a5 + b5T fitted by the least squares method is 0.167, b5 is 5.01×10 -4 .

[0073] like Figure 7 As shown, annealing temperature T6 * =1600℃ TG data of 6H-SiC crystal in the experimental group during the thermogravimetric test and the fitting curve of relative mass change Δ and annealing temperature T, where Δ6 = (m6-M6) / M6×100%. Combined with Table 1, it can be seen that the linear equation Δ6 = a6 + bT fitted by the least squares method has a6 of 0.171 and b6 of 5.906×10 -4 .

[0074] like Figure 8 As shown, annealing temperature T7 * =1700℃ TG data of 6H-SiC crystal in the experimental group during the thermogravimetric test and the fitting curve of relative mass change Δ and annealing temperature T, where Δ7 = (m7-M7) / M7×100%. Combined with Table 1, it can be seen that the linear equation Δ7 = a7 + b7T fitted by the least squares method is 0.197, b7 is 9.79×10 -4 .

[0075] S42. Establish temperature calibration equation: Figure 10As shown, the annealing temperature T* is used as the independent variable and the fitting parameter b in step S41 is used as the dependent variable to construct the polynomial equation b=α+βT*+γT*2+δT* 3 By adopting the polynomial equation (b=α+βT*+γT*2+δT*3), the thermogravimetric data is fitted to achieve dynamic compensation, which solves the problem of large deviation of the linear equation in the high temperature range. When the annealing temperature is in the high temperature range of 1500-1700℃, the quadratic term in the calibration equation can characterize the mass transition caused by stacking fault repair according to the analysis, and the cubic term corresponds to the recrystallization effect of the amorphous region. By fitting and analyzing the thermogravimetric test data of the 7 experimental groups in step S41, a relationship diagram between the fitting parameter b and the annealing temperature T* is drawn. Combined with Table 2, it can be seen that the calibration equation b=α+βT*+γT*2+δT* 3 , α = -138.22, β = 0.3138, γ = -2.373E-4, δ = 6.177E-8, and the correlation coefficient is 0.987.

[0076]

[0077] Table 2 Temperature calibration equation b=α+βT * +γT * 2+δT * 3. The values ​​of parameters α, β, γ, δ and the goodness of fit R 2 Value

[0078] S5. Determine the ambient temperature to be measured: Select four 6H-SiC crystals obtained by segmentation in step S3, place them in the environment to be measured and perform annealing treatment, then remove the annealed 6H-SiC crystals for thermogravimetric testing and analyze them according to the method of step S4 to obtain a Δ-T equation. The slope b0 of the Δ-T equation at the temperature to be measured is analyzed, and b0 is inversely calculated with the calibration equation obtained in step S42 to obtain the corresponding annealing temperature T*. The temperature value of T* is the ambient temperature to be measured. The effective temperature test range of this method is 1000-1700°C, and the residual is ≤±2%.

[0079] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A Si-based + The temperature measurement method of SiC crystal thermogravimetric analysis by dual ion and neutron irradiation is characterized in that: It includes the following steps: S1. Double irradiation of SiC crystal: SiC crystal is subjected to Si+ irradiation and neutron irradiation in sequence; S2, annealing treatment: the 6H-SiC crystal after the double irradiation in step S1 is annealed at a constant gradient temperature T * Annealing treatment is performed under S3, thermogravimetric test: step S2 is carried out at the annealing temperature T * The 6H-SiC crystals treated below were subjected to thermogravimetric testing one by one; S4. Processing the thermogravimetric test data: The heating temperature T during the thermogravimetric test and the corresponding relative mass change Δ of the 6H-SiC crystal are compared with the annealing temperature T. * The data were sorted to obtain the temperature calibration equation, and the annealing temperature T * As the independent variable and the fitting parameter b as the dependent variable, the temperature calibration equation b=α+βT is constructed. * +γT *2 +δT *3 , and determine the values ​​of the parameters in the polynomial equation; S5. Determine the ambient temperature to be measured: Anneal the double-irradiated 6H-SiC crystal in the test environment, then remove the annealed crystal for thermogravimetric testing to obtain a Δ-T equation, analyze the slope b0 of the Δ-T equation at the test ambient temperature, and obtain the corresponding annealing temperature T* by inversely calculating the temperature calibration equation in step S4. The annealing temperature T* is then the test ambient temperature.

2. The temperature measurement method based on thermogravimetric analysis of SiC crystals irradiated by Si+ ions and neutrons according to claim 1, characterized in that: The process of constructing the polynomial equation in step S4 also includes a Δ-T equation fitting step, in which the relative mass change Δ of the 6H-SiC crystal is calculated based on the thermogravimetric data obtained from the 6H-SiC crystal at different annealing temperatures, and a linear equation Δ=a+bT is obtained by fitting the relative mass change of the 6H-SiC crystal at different annealing temperatures and the temperature during the thermogravimetric process.

3. The Si-based method according to claim 2 + The temperature measurement method of SiC crystal thermogravimetric analysis by dual ion and neutron irradiation is characterized in that: During the thermogravimetric test process of step S3, nitrogen gas should be steadily introduced at a flow rate of 15 to 50 mL / min to form the nitrogen environment required for the thermogravimetric test. The heating rate of the thermogravimetric test is 5 to 10 ° C / min, the temperature range of the thermogravimetric test is 25 to 1400 ° C, and the mass measurement accuracy is ≤ 0.1 μg; before the start of the thermogravimetric test, the empty crucible baseline correction is repeated more than 3 times to obtain the average value, and the average value of the obtained empty crucible data is used as the baseline of the TG data.

4. The Si-based method according to claim 1 + The temperature measurement method of SiC crystal thermogravimetric analysis by dual ion and neutron irradiation is characterized in that: Step S1 includes the following sub-steps: S11, Si+ irradiation treatment: irradiating the SiC crystal with monoenergetic Si+ ions along the crystal c-axis; S12, neutron irradiation: Si + The irradiated SiC crystal is then subjected to neutron irradiation.

5. The Si-based method according to claim 4 + The temperature measurement method of SiC crystal thermogravimetric analysis by dual ion and neutron irradiation is characterized in that: The 6H-SiC crystal selected in step S1 is a nitrogen-doped 6H-SiC crystal, and the nitrogen doping concentration of the 6H-SiC crystal is 1×10 2 0~5×10 20 cm-3, Si + +1 valence Si selected during irradiation + Ions are irradiated ions, Si + The ion energy range is 0.1-1.0 MeV, Si + Total irradiation dose ≥10 16 cm-2, the irradiation temperature was controlled at 25±5℃, the irradiation direction was along the c-axis of the SiC crystal axis, and the crystal axis offset was ≤4°.

6. The Si-based method according to claim 1 + The temperature measurement method of SiC crystal thermogravimetric analysis by dual ion and neutron irradiation is characterized in that: Before annealing, the 6H-SiC crystal irradiated by neutrons in step S2 is divided into crystals with a mass of 5-10 mg. 4-6 divided SiC crystals are selected at different annealing temperatures and rapidly heated. The cut SiC crystals are heated from room temperature to the target temperature for a heating time of ≤4 min and then kept warm. After the heat preservation process is completed, the crystals are cooled to room temperature. The cut small SiC crystals are selected and the mass is recorded as M. The annealing temperature T * The constant gradient temperature range is 50-100℃, and the annealing temperature T * The range is 1000-1700℃, at the annealing temperature T * The holding time is ≥10min and the cooling rate is ≤20℃ / min.

7. The Si-based method according to claim 1 + The temperature measurement method of SiC crystal thermogravimetric analysis by dual ion and neutron irradiation is characterized in that: In step S2, the fast neutron irradiation is performed when the neutron flux is ≥1×10 14 n / (cm 2 ·s) under the condition of irradiation, and graphite moderator was used to control the energy spectrum distribution during the irradiation process. The neutron energy E>0.1MeV and the irradiation dose was 1×10 18 ~5×10 19 cm -2 , irradiation temperature ≤300℃.

8. The Si-based method according to claim 1 + The temperature measurement method of SiC crystal thermogravimetric analysis by dual ion and neutron irradiation is characterized in that: In step S5 , the relative mass change of the 6H—SiC crystal is Δ=(mM) / M×100%. The linear fitting of the Δ-T equation adopts the weighted least square method, and the weight coefficient is inversely proportional to the temperature measurement error.

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