Preparation method of AgBiSe2-based semiconductor crystal

Abstract

The invention relates to the field of semiconductor crystals, and discloses a preparation method of an AgBiSe2-based semiconductor crystal, which comprises the following steps: putting elementary substance particles into a crucible, sealing in vacuum, swinging and melting to prepare a polycrystalline raw material; the polycrystalline raw material is placed in a crucible for vacuum sealing, the crucible is placed in a vertical crystal growth device for melt growth, the AgBiSe2-based semiconductor crystal is prepared, and the melt growth conditions are as follows: the temperature gradient of a cooling zone is 15-30 DEG C / cm, and the movement rate of the crucible in the cooling zone is 0.2-3 mm / h; according to the present invention, the AgBiSe2-based semiconductor crystal is prepared by using the vertical melting growth method, the conductivity change rate of the prepared AgBiSe2-based semiconductor crystal in the temperature range of 300-550 K is significantly changed by controlling the conditions of the cooling region, and the temperature controllability of the AgBiSe2-based semiconductor crystal on the conductivity in the temperature range of 300-550 K can be further achieved;

Description

Technical Field

[0001] This invention relates to the field of semiconductor crystals, and in particular to a method for preparing AgBiSe2-based semiconductor crystals. Background Technology

[0002] AgBiSe2, as a potential semiconductor material with low lattice thermal conductivity, has broad application prospects in thermoelectric and optoelectronic fields. Its preparation research focuses on precursor optimization, structural stabilization, and process scaling. Currently, there are various methods for preparing AgBiSe2 materials. For example, the paper "High Thermoelectric and Reversible pnp Conduction Type Switching Integrated in Dimetal Chalcogenide" discloses a method for synthesizing AgBiSe2 nanocrystalline colloidal materials.

[0003] AgBiSe2 materials possess intrinsic defects, enabling them to exhibit both N-type and P-type conductivity. The N-type conductivity is formed by Se vacancies and BiAg antisite defects, while the P-type conductivity is formed by Ag vacancies and AgBi antisite defects. Therefore, directional manipulation of these defects can lock the conductivity type of AgBiSe2. For example, in a P-type AgBiSe2 thermoelectric material and its preparation method disclosed in publication CN119836214A, Mn doping transforms the conductivity of the AgBiSe2 thermoelectric material into P-type conductivity. This invention reveals significant differences in the conductivity of AgBiSe2 materials prepared by the above methods. Unmodified AgBiSe2 exhibits an extremely stable conductivity change rate in the mid-to-low temperature range, while the conductivity change rate in the mid-to-low temperature range changes significantly after Mn doping modification. This indicates that the conductivity of the modified AgBiSe2 material is significantly more sensitive to temperature, making this material promising for applications in fields such as intelligent sensing.

[0004] Further research revealed that CN104404284B discloses a method for rapidly preparing high-performance AgBiSe2 bulk thermoelectric materials. This method employs a thermal explosion reaction and discharge plasma sintering process to prepare AgBiSe2 thermoelectric materials. The conductivity of this material changes significantly with temperature. Analysis showed that the sintering temperature in this method is 550~650 ℃, while conventional melt growth methods involve melting at 950~1100 ℃ followed by furnace cooling. Therefore, this invention hypothesizes that temperature is the key factor causing the significant change in the conductivity of the material during melt growth. Therefore, this invention has conducted in-depth research on the above-mentioned aspects. Summary of the Invention

[0005] The purpose of this invention is to prepare P-type conductive pure-phase AgBiSe2-based semiconductors using a vertical melt growth method. By controlling the cooling zone conditions, the Seebeck coefficient of the AgBiSe2-based semiconductors can be adjusted to enable the semiconductor's conductivity to have high temperature sensitivity and controllability within the temperature range of 300~550 K.

[0006] The specific technical solution of this invention is as follows: A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Place the elemental particles into a crucible, seal it under vacuum, and then melt it by shaking to produce polycrystalline raw materials; (2) Place the polycrystalline raw material in a crucible and seal it under vacuum. Place the crucible in a vertical crystal growth device for melt growth to produce AgBiSe2-based semiconductor crystals. The melt growth conditions include: a temperature gradient of 15~30 ℃ / cm in the cooling zone and a crucible moving speed of 0.1~3 mm / h in the cooling zone.

[0007] Preferably, the temperature gradient in the cooling zone is 18~25 ℃ / cm, 0.8~1.5 mm / h.

[0008] As a preferred option, the conditions for melt growth also include: a melt zone temperature of 900~1100 ℃, a melt zone heating rate of 1~2.5 ℃ / min, and a melt zone residence time of 8~20 h.

[0009] As a preferred embodiment, the melting and rocking conditions include: a temperature of 900~1100 ℃, a time of 0.5~3 h, a rocking rate of 10~30 r / min, and a holding time of 0.5~3 h.

[0010] Preferably, the diameter of the AgBiSe2-based semiconductor crystal is 10~40 mm.

[0011] Preferably, the length of the AgBiSe2-based semiconductor crystal is 50~200 mm.

[0012] Preferably, the AgBiSe2-based semiconductor crystal has a P-type conductivity.

[0013] Preferably, the Seebeck coefficient of AgBiSe2-based semiconductor crystals at 300–550 K is 450–550 μ / VK.

[0014] Preferably, the AgBiSe2-based semiconductor crystal has a conductivity of 100-3000 S / m at 300-550 K.

[0015] Preferably, the bottom of the crucible is conical.

[0016] Preferably, the crucible is a quartz crucible.

[0017] Preferably, the crucible has a taper of 15-44°, a diameter of 10-50 mm, and a length of 200-400 mm.

[0018] Preferably, the elemental particles are elemental silver, elemental bismuth, and elemental selenium.

[0019] This invention provides a method for preparing AgBiSe2-based semiconductor crystals. The method uses a vertical melt growth method to prepare AgBiSe2-based semiconductor crystals, and the obtained AgBiSe2-based semiconductor crystals have a P-type conductivity. The AgBiSe2-based semiconductor crystals prepared by this method have high temperature sensitivity and temperature controllability in the temperature range of 300~500 K.

[0020] This invention reveals that AgBiSe2-based semiconductor crystals prepared by the conventional melt growth method exhibit stable conductivity in the temperature range of 300–550 K, but show significant conductivity changes in the temperature range of 500–800 K. Furthermore, AgBiSe2-based semiconductor crystals prepared by discharge plasma sintering also show significant conductivity changes in the 300–500 K temperature range. Analysis of these technical solutions reveals that the conventional melt growth method involves melting and holding at 900–1100 °C followed by furnace cooling, while the discharge plasma sintering process uses a temperature of 550–560 °C for sintering. Therefore, this invention hypothesizes that temperature is a crucial factor influencing the significant conductivity changes in the mid-to-low temperature range of AgBiSe2-based semiconductor crystals.

[0021] Based on the above, this invention selected the vertical melt growth method to prepare AgBiSe2-based semiconductor crystals. The vertical melt growth method includes a melting zone, a cooling zone, and an annealing zone. The cooling zone allows for the control of the temperature conditions during crystal growth. In practical operation, this invention found that controlling the conditions of the cooling zone not only significantly alters the rate of change of conductivity of the AgBiSe2-based semiconductor crystal in the medium-low temperature region, but also enables temperature controllability of the conductivity, giving AgBiSe2-based semiconductor crystals excellent application prospects in the field of temperature control.

[0022] Compared with the prior art, this application has the following technical effects: This invention uses a vertical melt growth method to prepare AgBiSe2-based semiconductor crystals. This method can significantly change the rate of change of conductivity of the prepared AgBiSe2-based semiconductor crystals in the temperature range of 300~550 K by controlling the cooling zone conditions, and can also achieve controllability of AgBiSe2-based semiconductor crystals in the temperature range of 300~550 K. Attached Figure Description

[0023] Figure 1 This is an appearance diagram of the AgBiSe2-based semiconductor crystal prepared in Example 1.

[0024] Figure 2 The image shows the X-ray diffraction pattern of the AgBiSe2-based semiconductor crystal prepared in Example 1.

[0025] Figure 3 The elemental distribution surface scan spectrum of the AgBiSe2-based semiconductor crystal prepared in Example 1 is shown.

[0026] Figure 4 The conductivity curves and Seebeck coefficient curves of the AgBiSe2-based semiconductor crystals prepared in Examples 1 and Comparative Examples 1 to 5 are shown in the range of 300 to 800 K.

[0027] Figure 5 The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystal prepared in Example 2 in the range of 300-800 K.

[0028] Figure 6 The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystal prepared in Example 3 in the range of 300-800 K.

[0029] Figure 7 The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystal prepared in Example 4 in the range of 300-800 K.

[0030] Figure 8 The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystal prepared in Example 5 in the range of 300-800 K.

[0031] Figure 9 The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystal prepared in Example 6 in the range of 300-800 K.

[0032] Figure 10 The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystal prepared in Example 7 in the range of 300-800 K.

[0033] Figure 11 The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystal prepared in Example 8 in the range of 300-800 K.

[0034] Figure 12The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystal prepared in Example 9 in the range of 300-800 K.

[0035] Figure 13 The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystal prepared in Example 10 in the range of 300-800 K. Detailed Implementation

[0036] The present invention will be further described below with reference to embodiments.

[0037] To better understand the content of this invention, further explanation is provided below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of this invention.

[0038] Example 1: A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Weigh out elemental Ag, elemental Bi and elemental Se in a molar ratio of 1:1:2. The purity of elemental Ag, elemental Bi and elemental Se is greater than 99.9%. Place elemental Ag, elemental Bi and elemental Se into a quartz crucible and seal it under vacuum. Raise the temperature of the swing furnace to 1000 ℃ and keep it at that temperature for 1 h to completely melt the elemental metals in the crucible. Then swing the crucible at a swing speed of 20 r / min for 1 h to ensure that the raw materials are fully mixed and homogeneous. Cool the crucible to produce AgBiSe2 polycrystalline raw material. (2) Take 80 g of the above AgBiSe2 polycrystalline raw material and place it in a quartz crucible (the quartz crucible has a diameter of 30 mm, a length of 200 mm, a conical bottom, and a taper of 30°), and evacuate it to 10°C. -3 After purging with argon gas and cycling three times, the quartz crucible was sealed with an oxyhydrogen flame. The quartz crucible was then vertically placed into the melting zone of a vertical growth furnace for vertical melt growth. The melting zone was heated to 1000 °C at a heating rate of 2 °C / min and held for 12 h. The quartz crucible was then moved to the cooling zone below the melting zone. The initial temperature of the cooling zone was 900 °C, and the cooling gradient was 18 °C / cm. The quartz crucible was slowly moved in the cooling zone at a moving rate of 0.8 mm / h until all the melt crystallized completely. The quartz crucible was then moved to the annealing zone and held for 12 h at a temperature of 500 °C. After the holding period, AgBiSe2-based semiconductor crystals were obtained with a diameter of 30 mm and a length of 100 mm.

[0039] Example 2: A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Weigh out elemental Ag, elemental Bi and elemental Se in a molar ratio of 1:1:2. The purity of elemental Ag, elemental Bi and elemental Se is greater than 99.9%. Place elemental Ag, elemental Bi and elemental Se into a quartz crucible and seal it under vacuum. Raise the temperature of the swing furnace to 1000 ℃ and keep it at that temperature for 1 h to completely melt the elemental metals in the crucible. Then swing the crucible at a swing speed of 20 r / min for 1 h to ensure that the raw materials are fully mixed and homogeneous. Cool the crucible to produce AgBiSe2 polycrystalline raw material. (2) Take 80 g of the above AgBiSe2 polycrystalline raw material and place it in a quartz crucible (the quartz crucible has a diameter of 30 mm, a length of 200 mm, a conical bottom, and a taper of 30°), and evacuate it to 10°C. -3 After purging with argon gas and cycling three times, the quartz crucible was sealed with an oxyhydrogen flame. The quartz crucible was then vertically placed into the melting zone of a vertical growth furnace for vertical melt growth. The melting zone was heated to 1000 °C at a heating rate of 2 °C / min and held for 12 h. The quartz crucible was then moved to the cooling zone below the melting zone. The initial temperature of the cooling zone was 900 °C and the cooling gradient was 19 °C / cm. The quartz crucible was slowly moved in the cooling zone at a moving rate of 0.9 mm / h until all the melt crystallized completely. The quartz crucible was then moved to the annealing zone and held for 12 h at a temperature of 500 °C. After the holding period, AgBiSe2-based semiconductor crystals were produced with a diameter of 30 mm and a length of 100 mm.

[0040] Example 3: A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Weigh out elemental Ag, elemental Bi and elemental Se in a molar ratio of 1:1:2. The purity of elemental Ag, elemental Bi and elemental Se is greater than 99.9%. Place elemental Ag, elemental Bi and elemental Se into a quartz crucible and seal it under vacuum. Raise the temperature of the swing furnace to 1100 ℃ and keep it at that temperature for 0.5 h to completely melt the elemental metals in the crucible. Then swing the crucible at a swing speed of 30 r / min for 0.5 h to mix the raw materials thoroughly and evenly. Cool the crucible to produce AgBiSe2 polycrystalline raw material. (2) Take 80 g of the above AgBiSe2 polycrystalline raw material and place it in a quartz crucible (the quartz crucible has a diameter of 40 mm, a length of 200 mm, a conical bottom, and a taper of 30°), and evacuate it to 10°C. -3After purging with argon gas and cycling three times, the quartz crucible was sealed with an oxyhydrogen flame. The quartz crucible was then vertically placed into the melting zone of a vertical growth furnace for vertical melt growth. The melting zone was heated to 1000 °C at a heating rate of 2 °C / min and held for 12 h. The quartz crucible was then moved to the cooling zone below the melting zone. The initial temperature of the cooling zone was 900 °C, and the cooling gradient was 20 °C / cm. The quartz crucible was slowly moved in the cooling zone at a moving rate of 1 mm / h until all the melt crystallized. The quartz crucible was then moved to the annealing zone and held for 12 h at a temperature of 500 °C. After the holding period, AgBiSe2-based semiconductor crystals were obtained with a diameter of 40 mm and a length of 150 mm.

[0041] Example 4: A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Weigh out elemental Ag, elemental Bi and elemental Se in a molar ratio of 1:1:2. The purity of elemental Ag, elemental Bi and elemental Se is greater than 99.9%. Place elemental Ag, elemental Bi and elemental Se into a quartz crucible and seal it under vacuum. Raise the temperature of the swing furnace to 900 ℃ and keep it at that temperature for 3 h to completely melt the elemental metals in the crucible. Then swing the crucible at a swing speed of 10 r / min for 3 h to ensure that the raw materials are fully mixed and homogeneous. Cool the crucible to produce AgBiSe2 polycrystalline raw material. (2) Take 80 g of the above AgBiSe2 polycrystalline raw material and place it in a quartz crucible (the quartz crucible has a diameter of 30 mm, a length of 200 mm, a conical bottom, and a taper of 30°), and evacuate it to 10°C. -3 After purging with argon gas and cycling three times, the quartz crucible was sealed with an oxyhydrogen flame. The quartz crucible was then vertically placed into the melting zone of a vertical growth furnace for vertical melt growth. The melting zone was heated to 1000 °C at a heating rate of 2 °C / min and held for 12 h. The quartz crucible was then moved to the cooling zone below the melting zone. The initial temperature of the cooling zone was 900 °C, and the cooling gradient was 21 °C / cm. The quartz crucible was slowly moved in the cooling zone at a moving rate of 1.1 mm / h until all the melt crystallized. The quartz crucible was then moved to the annealing zone and held for 12 h at a temperature of 500 °C. After the holding period, AgBiSe2-based semiconductor crystals were obtained with a diameter of 30 mm and a length of 100 mm.

[0042] Example 5: A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Weigh out elemental Ag, elemental Bi and elemental Se in a molar ratio of 1:1:2. The purity of elemental Ag, elemental Bi and elemental Se is greater than 99.9%. Place elemental Ag, elemental Bi and elemental Se into a quartz crucible and seal it under vacuum. Raise the temperature of the swing furnace to 1000 ℃ and keep it at that temperature for 1 h to completely melt the elemental metals in the crucible. Then swing the crucible at a swing speed of 20 r / min for 1 h to ensure that the raw materials are fully mixed and homogeneous. Cool the crucible to produce AgBiSe2 polycrystalline raw material. (2) Take 80 g of the above AgBiSe2 polycrystalline raw material and place it in a quartz crucible (the quartz crucible has a diameter of 30 mm, a length of 200 mm, a conical bottom, and a taper of 30°), and evacuate it to 10°C. -3 After purging with argon gas and cycling three times, the quartz crucible was sealed with an oxyhydrogen flame. The quartz crucible was then vertically placed into the melting zone of a vertical growth furnace for vertical melt growth. The melting zone was heated to 1000 ℃ at a heating rate of 0.5 ℃ / min and held for 20 h. The quartz crucible was then moved to the cooling zone below the melting zone. The initial temperature of the cooling zone was 900 ℃, and the cooling gradient was 22 ℃ / cm. The quartz crucible was slowly moved in the cooling zone at a moving rate of 1.2 mm / h until all the melt crystallized completely. The quartz crucible was then moved to the annealing zone and held for 12 h at a temperature of 500 ℃. After the holding period, AgBiSe2-based semiconductor crystals were produced with a diameter of 30 mm and a length of 100 mm.

[0043] Example 6: A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Weigh out elemental Ag, elemental Bi and elemental Se in a molar ratio of 1:1:2. The purity of elemental Ag, elemental Bi and elemental Se is greater than 99.9%. Place elemental Ag, elemental Bi and elemental Se into a quartz crucible and seal it under vacuum. Raise the temperature of the swing furnace to 1000 ℃ and keep it at that temperature for 1 h to completely melt the elemental metals in the crucible. Then swing the crucible at a swing speed of 20 r / min for 1 h to ensure that the raw materials are fully mixed and homogeneous. Cool the crucible to produce AgBiSe2 polycrystalline raw material. (2) Take 80 g of the above AgBiSe2 polycrystalline raw material and place it in a quartz crucible (the quartz crucible has a diameter of 30 mm, a length of 200 mm, a conical bottom, and a taper of 30°), and evacuate it to 10°C. -3After purging with argon gas and cycling three times, the quartz crucible was sealed with an oxyhydrogen flame. The quartz crucible was then vertically placed in the melting zone of a vertical growth furnace for vertical melt growth. The melting zone was heated to 1100 ℃ at a heating rate of 1.5 ℃ / min and held for 8 h. The quartz crucible was then moved to the cooling zone below the melting zone. The initial temperature of the cooling zone was 900 ℃, and the cooling gradient was 23 ℃ / cm. The quartz crucible was slowly moved in the cooling zone at a moving rate of 1.3 mm / h until all the melt crystallized completely. The quartz crucible was then moved to the annealing zone and held for 12 h at a temperature of 500 ℃. After the holding period, AgBiSe2-based semiconductor crystals were obtained with a diameter of 30 mm and a length of 100 mm.

[0044] Example 7: A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Weigh out elemental Ag, elemental Bi and elemental Se in a molar ratio of 1:1:2. The purity of elemental Ag, elemental Bi and elemental Se is greater than 99.9%. Place elemental Ag, elemental Bi and elemental Se into a quartz crucible and seal it under vacuum. Raise the temperature of the swing furnace to 1000 ℃ and keep it at that temperature for 1 h to completely melt the elemental metals in the crucible. Then swing the crucible at a swing speed of 20 r / min for 1 h to ensure that the raw materials are fully mixed and homogeneous. Cool the crucible to produce AgBiSe2 polycrystalline raw material. (2) Take 80 g of the above AgBiSe2 polycrystalline raw material and place it in a quartz crucible (the quartz crucible has a diameter of 10 mm, a length of 200 mm, a conical bottom, and a taper of 30°), and evacuate it to 10°C. -3 After purging with argon gas and cycling three times, the quartz crucible was sealed with an oxyhydrogen flame. The quartz crucible was then vertically placed into the melting zone of a vertical growth furnace for vertical melt growth. The melting zone was heated to 1000 °C at a heating rate of 2 °C / min and held for 12 h. The quartz crucible was then moved to the cooling zone below the melting zone. The initial temperature of the cooling zone was 900 °C, and the cooling gradient was 24 °C / cm. The quartz crucible was slowly moved in the cooling zone at a moving rate of 1.4 mm / h until all the melt crystallized completely. The quartz crucible was then moved to the annealing zone and held for 12 h at a temperature of 500 °C. After the holding period, AgBiSe2-based semiconductor crystals were obtained with a diameter of 10 mm and a length of 50 mm.

[0045] Example 8: A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Weigh out elemental Ag, elemental Bi and elemental Se in a molar ratio of 1:1:2. The purity of elemental Ag, elemental Bi and elemental Se is greater than 99.9%. Place elemental Ag, elemental Bi and elemental Se into a quartz crucible and seal it under vacuum. Raise the temperature of the swing furnace to 1000 ℃ and keep it at that temperature for 1 h to completely melt the elemental metals in the crucible. Then swing the crucible at a swing speed of 20 r / min for 1 h to ensure that the raw materials are fully mixed and homogeneous. Cool the crucible to produce AgBiSe2 polycrystalline raw material. (2) Take 80 g of the above AgBiSe2 polycrystalline raw material and place it in a quartz crucible (the quartz crucible has a diameter of 30 mm, a length of 200 mm, a conical bottom, and a taper of 30°), and evacuate it to 10°C. -3 After purging with argon gas and cycling three times, the quartz crucible was sealed with an oxyhydrogen flame. The quartz crucible was then vertically placed into the melting zone of a vertical growth furnace for vertical melt growth. The melting zone was heated to 1000 °C at a heating rate of 2 °C / min and held for 12 h. The quartz crucible was then moved to the cooling zone below the melting zone. The initial temperature of the cooling zone was 900 °C, and the cooling gradient was 25 °C / cm. The quartz crucible was slowly moved in the cooling zone at a moving rate of 1.5 mm / h until all the melt crystallized completely. The quartz crucible was then moved to the annealing zone and held for 12 h at a temperature of 500 °C. After the holding period, AgBiSe2-based semiconductor crystals were produced with a diameter of 30 mm and a length of 100 mm.

[0046] Example 9: A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Weigh out elemental Ag, elemental Bi and elemental Se in a molar ratio of 1:1:2. The purity of elemental Ag, elemental Bi and elemental Se is greater than 99.9%. Place elemental Ag, elemental Bi and elemental Se into a quartz crucible and seal it under vacuum. Raise the temperature of the swing furnace to 900 ℃ and keep it at that temperature for 3 h to completely melt the elemental metals in the crucible. Then swing the crucible at a swing speed of 30 r / min for 0.5 h to mix the raw materials thoroughly and evenly. Cool the crucible to produce AgBiSe2 polycrystalline raw material. (2) Take 80 g of the above AgBiSe2 polycrystalline raw material and place it in a quartz crucible (the quartz crucible has a diameter of 30 mm, a length of 200 mm, a conical bottom, and a taper of 30°), and evacuate it to 10°C. -3After purging with argon gas and circulating three times, the quartz crucible was sealed with an oxyhydrogen flame. The quartz crucible was then vertically placed into the melting zone of a vertical growth furnace for vertical melt growth. The melting zone was heated to 1100 ℃ at a heating rate of 2.5 ℃ / min and held for 8 h. The quartz crucible was then moved to the cooling zone below the melting zone. The initial temperature of the cooling zone was 900 ℃, and the cooling gradient was 15 ℃ / cm. The quartz crucible was slowly moved in the cooling zone at a moving rate of 0.5 mm / h until all the melt crystallized completely. The quartz crucible was then moved to the annealing zone and held for 12 h at a temperature of 500 ℃. After the holding period, AgBiSe2-based semiconductor crystals were obtained with a diameter of 30 mm and a length of 100 mm.

[0047] Example 10 A method for preparing an AgBiSe2-based semiconductor crystal includes the following steps: (1) Weigh out elemental Ag, elemental Bi and elemental Se in a molar ratio of 1:1:2. The purity of elemental Ag, elemental Bi and elemental Se is greater than 99.9%. Place elemental Ag, elemental Bi and elemental Se into a quartz crucible and seal it under vacuum. Raise the temperature of the swing furnace to 1100 ℃ and keep it at that temperature for 0.5 h to completely melt the elemental metals in the crucible. Then swing the crucible at a swing speed of 10 r / min for 3 h to ensure that the raw materials are fully mixed and homogeneous. Cool the crucible to produce AgBiSe2 polycrystalline raw material. (2) Take 80 g of the above AgBiSe2 polycrystalline raw material and place it in a quartz crucible (the quartz crucible has a diameter of 30 mm, a length of 200 mm, a conical bottom, and a taper of 30°), and evacuate it to 10°C. -3 After purging with argon gas and circulating three times, the quartz crucible was sealed with an oxyhydrogen flame. The quartz crucible was then vertically placed into the melting zone of a vertical growth furnace for vertical melt growth. The melting zone was heated to 900 °C at a rate of 1 °C / min and held for 20 h. The quartz crucible was then moved to the cooling zone below the melting zone. The initial temperature of the cooling zone was 900 °C, and the cooling gradient was 30 °C / cm. The quartz crucible was slowly moved in the cooling zone at a rate of 3 mm / h until all the melt crystallized. The quartz crucible was then moved to the annealing zone and held for 12 h at a temperature of 500 °C. After the holding period, AgBiSe2-based semiconductor crystals were obtained with a diameter of 30 mm and a length of 100 mm.

[0048] Comparative Example 1: Comparative Example 1 uses the method disclosed in CN119836214A to prepare AgBiSe2-based semiconductor crystals.

[0049] Comparative Example 2: Comparative Example 2 uses the method disclosed in CN104404284B to prepare AgBiSe2-based semiconductor crystals.

[0050] Comparative Example 3: Comparative Example 3 uses the method disclosed in "High Thermoelectric and Reversible pnp Conduction Type Switching Integrated in Dimetal Chalcogenide" to prepare AgBiSe2-based semiconductor crystals.

[0051] Comparative Example 4: The difference between Comparative Example 4 and the Example 1 is that the cooling gradient is 40 °C / cm, and the moving speed of the quartz crucible in the cooling zone is 3.5 mm / h. All other conditions are the same as in Example 1.

[0052] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that the temperature gradient is 10 °C / cm and the moving speed of the quartz crucible in the cooling zone is 0.1 mm / h. All other conditions are the same as in Example 1.

[0053] Example of detection: The conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystals prepared in Examples 1-10 and Comparative Examples 1-5 were tested, and the test results are shown in [Figure number missing]. Figures 4-13 .

[0054] like Figures 4-13 As shown, Figure 4 The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystals prepared in Example 1 and Comparative Examples 1-5. As can be seen from the graphs, the conductivity of the AgBiSe2-based semiconductor crystal in Example 1 of this invention is 250-3000 S / m in the temperature range of 300-550 K. The conductivity first increases and then decreases with increasing temperature, and the rate of change of conductivity changes significantly with increasing temperature. The Seebeck coefficient of the AgBiSe2-based semiconductor crystal in the temperature range of 300-550 K is 450-550 μ / VK, and the Seebeck coefficient does not change significantly with increasing temperature. These results indicate that the AgBiSe2-based semiconductor crystal prepared in Example 1 of this invention exhibits conductivity within the temperature range of 300-550 K. The semiconductor exhibits high temperature sensitivity in the mid-to-low temperature range, and the Seebeck coefficient does not change significantly within this temperature range. This indicates that the semiconductor has stable thermoelectric conversion performance within this temperature range. The conductivity of the semiconductor can be controlled by adjusting the temperature, thereby controlling the thermoelectric conversion efficiency. At the same time, it can also avoid large fluctuations in conversion efficiency due to temperature changes, making the semiconductor crystal temperature controllable.

[0055] Comparative Example 1 is a conventional melt growth method for preparing AgBiSe2-based semiconductor crystals. The semiconductor crystals prepared by this method show no significant changes in conductivity and Seebeck coefficient within the temperature range of 300~550 K, indicating that the semiconductor crystals have low temperature sensitivity and stable thermoelectric conversion performance in the medium and low temperature range.

[0056] Comparative Example 2 is a technical scheme for preparing AgBiSe2-based semiconductor crystals by discharge plasma sintering. The semiconductor crystals prepared by this scheme showed significant changes in conductivity within the temperature range of 400~450 K, and their Seebeck coefficient also showed significant changes. This result indicates that although the semiconductor has high temperature sensitivity in the medium and low temperature range, it does not have temperature controllability. In addition, the semiconductor crystals prepared in the comparative example are of the N-type conductivity type.

[0057] Comparative Example 3 illustrates a technique for preparing AgBiSe2-based semiconductor crystals using a colloidal synthesis method. The semiconductor crystals prepared using this method exhibited significant changes in conductivity within the temperature range of 500–700 K, while the conductivity remained relatively constant within the temperature range of 300–500 K. This indicates that the semiconductor has low temperature sensitivity in the mid-to-low temperature range.

[0058] Comparative Examples 4 and 5 further explored the cooling gradient, and the results showed that both excessively high and excessively low cooling gradients would significantly reduce the rate of change of the semiconductor's conductivity, thereby reducing the semiconductor's temperature sensitivity.

[0059] Figures 5-13 The graphs show the conductivity and Seebeck coefficient of the AgBiSe2-based semiconductor crystals prepared in Examples 2-10. The results show that the conductivity and Seebeck coefficient of the semiconductor crystals prepared in Examples 2-8 exhibit the same trend as in Example 1 with increasing temperature. The conductivity of the semiconductor crystals prepared in Examples 9-10 also exhibits the same trend as in Example 1 with increasing temperature. However, the Seebeck coefficient of the semiconductor crystals prepared in Examples 9-10 shows a significant change with increasing temperature, and the stability of the Seebeck coefficient in the temperature range of 300-550K is significantly reduced. These results indicate that the cooling zone conditions of the vertical melt growth method have a significant impact on the Seebeck coefficient of the AgBiSe2-based semiconductor crystal. Only when the cooling gradient is 18-25℃ / cm and the crucible moving speed is 0.8-1.5 mm / h can the AgBiSe2-based semiconductor crystals prepared exhibit high temperature sensitivity and controllability in the temperature range of 300-550K.

[0060] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing AgBiSe2-based semiconductor crystals, characterized in that, Includes the following steps: (1) Place the elemental particles into a crucible, seal it under vacuum, and then melt it by shaking to produce polycrystalline raw materials; (2) Place the polycrystalline raw material in a crucible and seal it under vacuum. Place the crucible in a vertical crystal growth device for melt growth to produce AgBiSe2-based semiconductor crystals. The melt growth conditions include: a temperature gradient of 15~30 ℃ / cm in the cooling zone and a crucible moving speed of 0.2~3 mm / h in the cooling zone.

2. The preparation method according to claim 1, characterized in that, The melting and rocking conditions include: temperature of 900~1100℃, time of 0.5~3 h, rocking rate of 10~30 r / min, and holding time of 0.5~3 h.

3. The preparation method according to claim 1, characterized in that, The conditions for melt growth also include: a melt zone temperature of 900~1100 ℃, a melt zone heating rate of 1~2.5 ℃ / min, and a melt zone residence time of 8~20 h.

4. The method according to claim 1, characterized in that, The diameter of AgBiSe2-based semiconductor crystals is 10~40 mm; the length of AgBiSe2-based semiconductor crystals is 50~200 mm.

5. The method according to claim 1, characterized in that, AgBiSe2-based semiconductor crystals have a P-type conductivity.

6. The method according to claim 1, characterized in that, The Zebeck coefficient of AgBiSe2-based semiconductor crystals at 300–550 K is 450–550 μ / VK; the conductivity of AgBiSe2-based semiconductor crystals at 300–550 K is 100–3000 S / m.

7. The method according to claim 1, characterized in that, The bottom of the crucible is conical.

8. The method according to claim 1, characterized in that, The crucible is a quartz crucible.

9. The method according to claim 1, 7, or 8, characterized in that, The crucible has a taper of 15-44°, a diameter of 10-50 mm, and a length of 200-400 mm.

10. The method according to claim 1, characterized in that, The elemental particles are silver, bismuth, and selenium.

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