P-type Mg3Sb2 semiconductor material with high density and high conductivity as well as preparation method and application of p-type Mg3Sb2 semiconductor material

Abstract

The invention discloses a p-type Mg3Sb2 semiconductor material with high density and high conductivity and a preparation method and application of the p-type Mg3Sb2 semiconductor material. Magnesium powder and antimony powder are calculated and weighed according to the substance amount ratio of Mg3Sb2 and then put into a ball milling tank, the ball milling tank is put into a transition bin of a glove box for gas washing, the ball milling tank is filled with argon in the glove box, and then the ball milling tank is rapidly sealed; and carrying out mechanical alloying reaction by adopting a high-energy ball milling method, and then carrying out hot pressed sintering and abrasive paper polishing to obtain the p-type Mg3Sb2 semiconductor material with high density and high conductivity. The method has the characteristics of easily available raw materials and equipment, simple process and low energy consumption.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor material synthesis, and in particular relates to a p-type Mg3Sb2 semiconductor material with high density and high conductivity, a preparation method thereof, and an application thereof. Background Art

[0002] Density and conductivity are two important parameters for measuring semiconductor performance. Studies have shown that increasing the compaction density of powder materials will reduce the gaps between particles, forming a more continuous conductive network and significantly improving the conductivity.

[0003] Hefei Guoxuan High-Tech Power Energy Co., Ltd. has developed a high-density, low-resistance lithium iron phosphate and its preparation method: CN202010152179.8[P].2022-05-06; this technology is relatively cumbersome, with long sintering time and high energy consumption, and low pressure, resulting in a large number of pores on the sample surface, affecting further optimization of density and conductivity.

[0004] In recent years, with the continuous development of semiconductor materials, magnesium-based semiconductors, especially binary magnesium-based compounds, have been widely used in semiconductor optoelectronic devices and electronic devices due to their unique electrical properties, low price, high abundance of elements and environmental friendliness.

[0005] As a typical Zintl phase semiconductor material, Mg3Sb2 has attracted widespread attention in recent years in the fields of energy conversion, optoelectronics, and quantum technology due to its unique electronic structure and environmentally friendly properties. For undoped Mg3Sb2, due to the negative charge of thermally activated vacancies, it exhibits intrinsic p-type characteristics. The high vapor pressure and high chemical activity of Mg easily lead to Mg vacancy defects, resulting in a conductivity of Mg3Sb2 of about 2000s / m and a theoretical density of about 4.088g / cm 3 (Shuai J,Wang Y,KimH S,et al.Thermoelectric properties of Na-doped Zintl compound:Mg 3-x Na x Sb2[J]. Acta Materialia, 2015, 93: 187-193.), the inherent low electrical conductivity limits the application of this material in the semiconductor field. The high vapor pressure and high chemical activity of Mg make it difficult to control the actual chemical composition and microstructure of Mg3Sb2 semiconductor materials during the preparation process, and it is impossible to obtain high-density and high-conductivity Mg3Sb2 semiconductor materials. Bhardwaj et al. prepared Mg3Sb2 by low-speed mechanical grinding, mortar grinding and spark plasma sintering, and the sample density was 3.94g / cm 3, which is about 96% of the theoretical density, and its maximum conductivity at around 773K is about 2400s / m (Bhardwaj A, Misra DK. Enhancing thermoelectric properties of a p-type Mg3Sb2-based Zintl phase compound by Pb substitution in the anionic framework[J]. Rsc Advances, 2014, 4(65): 34552-34560.); Minati et al. prepared Mg3Sb2 by ball milling and hot pressing sintering. The density of the sample was about 98% of the theoretical density. However, due to the preparation in air and the lack of argon protection, the maximum conductivity at around 773K was about 2500s / m (Tiadi M, Battabyal M, Jain PK, et al. Enhancing thethermoelectric efficiency in p-type Mg3Sb2 via Mg site co-doping[J]. Sustainable Energy & Fuels, 2021,5(16):4104-4114.).

[0006] The p-type Mg3Sb2 semiconductor materials prepared by the above methods are difficult to achieve both high density and high conductivity at the same time, which limits the application of Mg3Sb2 semiconductor materials in optoelectronic, thermoelectric devices, catalytic chemistry, radiation detection, infrared sensing and other fields. Summary of the Invention

[0007] In order to overcome the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a p-type Mg3Sb2 semiconductor material with high density and high conductivity, a preparation method and application thereof, and the semiconductor material and its preparation method have the characteristics of easy availability of raw materials and equipment, simple process and low energy consumption.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A p-type Mg3Sb2 semiconductor material with high density and high conductivity, with a relative density of ≥99% at room temperature and a conductivity of 3200-3400 S / m at around 773K;

[0010] The tightly stacked layered structure in the microscopic morphology of the p-type Mg3Sb2 semiconductor material constructs a conductive channel, conducts current transmission within and between layers, and improves carrier mobility, thereby obtaining a p-type Mg3Sb2 semiconductor material with both high density and high conductivity.

[0011] A method for preparing a p-type Mg3Sb2 semiconductor material with high density and high conductivity comprises the following steps:

[0012] Calculate and weigh the magnesium powder and antimony powder according to the molar ratio of Mg3Sb2, then load them into a ball mill, place the ball mill in the transition chamber of a glove box for air washing, fill the ball mill with argon in the glove box, and then quickly seal the ball mill.

[0013] A p-type Mg3Sb2 semiconductor material with high density and high conductivity was obtained by mechanical alloying through high-energy ball milling, followed by hot pressing, sintering, and sandpaper polishing. The experimental raw materials involved only magnesium and antimony powders, and no grinding aids, additives, or lubricants were added during the preparation process.

[0014] Preferably, the purity of the magnesium powder is ≥99.5%, and the purity of the antimony powder is 99.9%.

[0015] Preferably, the purity of the argon gas is ≥99.999%.

[0016] Preferably, the ball milling conditions are: the ball mill speed is 1000-1500 r / min, the ball milling time is 6-10 h, and the ball-to-material ratio is 10:1-15:1. The ball milling conditions can make the raw materials react fully to obtain a powder containing the main crystal phase Mg3Sb2 and a small amount of secondary crystal phase Sb.

[0017] Preferably, the current for hot pressing sintering is AC, the rated voltage of the hot pressing furnace is three-phase, 380V, 50Hz, and the rated power is 15KW.

[0018] Preferably, the vacuum degree of hot pressing sintering is 1.0×10 -2 Pa~8.0×10 -2 Pa.

[0019] The sintering temperature of hot pressing sintering is 600-650° C., the sintering heating rate is 5-10° C. / min, and the holding time is 2-5 min.

[0020] Preferably, the heating and cooling process of hot pressing sintering is mainly divided into three stages. The first stage adopts manual heating, the voltage is adjusted to 2~4V, the current is adjusted to 0.3~0.5KA, and the temperature is raised from room temperature to 180℃~220℃; the second stage adopts automatic heating, and the temperature is continued to rise to 580℃~620℃, and kept warm for 2~5min; the third stage adopts automatic cooling, and the machine's own circulating water cooling system is used for cooling, and the temperature is cooled to 80℃~100℃ and the instrument is turned off.

[0021] Preferably, the sintering pressure is applied between 300℃ and 350℃, with a pressure growth rate of 2Mpa / min. When the temperature reaches 600℃, the pressure reaches 60Mpa, and then the pressure is maintained for 1 to 2 hours, and then the hydraulic button is turned off. This hot pressing condition can make the sample have a denser structure.

[0022] Preferably, the grinding conditions are: first use 280-500 mesh sandpaper for coarse grinding, and then use 2000-2500 mesh sandpaper for fine grinding.

[0023] A p-type Mg3Sb2 semiconductor material with high density and high conductivity can be used in infrared detectors, low-power magnetic storage, radiation detectors, self-powered sensors and thermoelectric energy converters.

[0024] Beneficial effects of the present invention:

[0025] The present invention prepares a p-type Mg3Sb2 semiconductor material with good crystallinity, dense structure, strong repeatability and high conductivity through a simple mechanical alloying, ball milling and vacuum hot pressing sintering method. Its relative density reaches 99.07% and the conductivity is as high as 3311s / m.

[0026] This vacuum hot-pressing process uses a step-by-step heating process and slow extrusion. This avoids the drawback of rapid volatilization of the Mg element due to rapid heating. This allows for sufficient bonding between the elements of the compound, resulting in a denser structure and significantly improved material stability. Furthermore, the tightly packed layered structure facilitates the formation of conductive pathways, enabling current transfer within and between layers, increasing carrier mobility and optimizing electrical conductivity, thus enhancing the service performance of p-type Mg3Sb2 semiconductor materials to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the XRD pattern of Example 1 of the present invention.

[0028] Figure 2 This is the temperature-conductivity diagram of Example 1 of the present invention.

[0029] Figure 3 This is the SEM image of Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be described in further detail below with reference to the accompanying drawings.

[0031] The present invention provides a p-type Mg3Sb2 semiconductor material with high density and high conductivity, and a method for preparing the same. In the invention, the Mg3Sb2 sample is prepared without the addition of ball-milling aids such as stearic acid, allowing the high-density and high-conductivity sample to be produced through a simple process. In Mg3Sb2, magnesium atoms typically exhibit a +2 valence, while antimony atoms exhibit a -3 valence. This unique chemical bonding gives Mg3Sb2 its unique electronic structure and physical properties.

[0032] In the present invention, magnesium powder and antimony powder are washed and sealed in a glove box, and then ball-milled to obtain a mixed powder. The mixed powder is then vacuum hot-pressed and sintered to obtain the p-type Mg3Sb2 semiconductor material.

[0033] The present invention does not specifically limit the sources of the magnesium powder and antimony powder; commercially available products familiar to those skilled in the art may be used. In an embodiment of the present invention, the Mg powder preferably has a purity of ≥99.5%, is preferably supplied by Shanghai Aladdin Biochemical Technology Co., Ltd., and is preferably stored in a glove box. The Sb powder preferably has a purity of 99.9%, is preferably supplied by Shanghai McLean Biochemical Technology Co., Ltd., and is preferably stored in a glove box.

[0034] In the present invention, the inert atmosphere is preferably high-purity argon in a glove box, more preferably high-purity argon with a water and oxygen content of less than 1 ppm, and most preferably high-purity argon with a water and oxygen content of less than 0.1 ppm. In the present invention, sealing the raw materials in an inert atmosphere reduces their contact with air, preventing oxidation, thereby improving the density and electrical properties of the product.

[0035] In the present invention, the ball milling method is preferably a high-energy vibration ball mill. The ball mill is preferably a Kejing MSK-SFM-3 high-speed vibration ball mill. The ball mill speed is preferably 1000-1500 rpm, more preferably 1200 rpm. The power of the ball mill is preferably 160-200 W, more preferably 180 W. The ball mill timing range is 0-30 minutes, more preferably 30 minutes. By limiting the ball milling parameters, the present invention ensures the ball milling effect and allows all raw materials to fully contact and react.

[0036] In the embodiments of the present invention, preferably 6-10 g of raw material is weighed each time and placed in an 80-100 mL stainless steel ball mill, and the ball-to-material ratio is preferably 10:1. The present invention improves material properties by controlling the amount of raw material ball milled each time to avoid uneven milling due to insufficient ball milling or agglomeration of raw materials due to excessive ball milling, thereby reducing the ball milling effect.

[0037] In the present invention, the ball milling time is preferably 6 to 10 hours, more preferably 8 hours. In the present invention, the powder adhering to the wall of the ball mill is preferably scraped off every 4 hours until the ball milling is completed. In the present invention, the ball milling effect is improved by controlling the process parameters of the ball milling process, ensuring sufficient contact between the particles of each element.

[0038] After ball milling, the present invention preferably crushes and grinds the ball milled product. The grinding time is preferably 10 minutes, and the grinding container is preferably an agate mortar. By grinding the ball milled powder, the present invention can further reduce the powder particle size, avoid the formation of large particles, and lay the foundation for subsequent sintering.

[0039] After obtaining the ground powder, the present invention applies a mold to the powder, wherein the aperture of the mold is preferably 11 to 14 mm, more preferably 12.7 mm. The mass of the powder is preferably 1.5 to 2.5 g, and the powder is wrapped with carbon paper.

[0040] In the present invention, the sintering method is preferably vacuum hot pressing sintering, the current of hot pressing sintering is AC, the rated voltage of the hot pressing furnace is three-phase, 380V, 50Hz, and the rated power is 15KW. The vacuum degree of sintering is preferably 6.0×10 -2 Pa. The present invention limits the sintering method to fully compress the sample and increase the density.

[0041] In the present invention, the sintering temperature is preferably 600° C., the heating rate is preferably 10° C. / min, the holding time is preferably 2 min, and the holding time is preferably 1.5 h.

[0042] The sandpaper in the present invention is preferably Eagle brand sandpaper, preferably 320 mesh for coarse grinding and 2000 mesh for fine grinding.

[0043] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0044] Example 1

[0045] The p-type Mg3Sb2 semiconductor material with high density and high conductivity has a chemical formula of Mg3Sb2 and a preparation method comprising the following steps:

[0046] Weigh 1.7965 g of magnesium powder and 6.0000 g of antimony powder, wash them in a glove box, seal the can, and use high-energy ball milling for 8 h at a speed of 1200 r / min and a ball-to-material ratio of 10:1 to obtain Mg3Sb2 powder.

[0047] The Mg3Sb2 powder was placed in a vacuum hot pressing sintering mold and the vacuum degree was adjusted to 6.0×10 -2 Pa, the sintering temperature is 600℃, the heating rate is 10℃ / min, the holding time is 2min, and the pressure holding time is 1.5h, and finally the bulk Mg3Sb2 material is obtained.

[0048] Then use 320-mesh and 2000-mesh sandpaper for coarse grinding and fine grinding in sequence to obtain p-type Mg3Sb2 semiconductor material.

[0049] Example 2

[0050] The p-type Mg3Sb2 semiconductor material with high density and high conductivity has a chemical formula of Mg3Sb2 and a preparation method comprising the following steps:

[0051] Weigh 1.4971 g of magnesium powder and 5.0000 g of antimony powder, wash them in a glove box, seal the can, and use high-energy ball milling for 8 h at a speed of 1200 r / min and a ball-to-material ratio of 10:1 to obtain Mg3Sb2 powder.

[0052] The Mg3Sb2 powder was placed in a vacuum hot pressing sintering mold and the vacuum degree was adjusted to 6.0×10 -2 Pa, the sintering temperature is 600℃, the heating rate is 10℃ / min, the holding time is 2min, and the pressure holding time is 1.5h, and finally the bulk Mg3Sb2 material is obtained.

[0053] Then use 320-mesh and 2000-mesh sandpaper for coarse grinding and fine grinding in sequence to obtain p-type Mg3Sb2 semiconductor material.

[0054] Example 3

[0055] The p-type Mg3Sb2 semiconductor material with high density and high conductivity has a chemical formula of Mg3Sb2 and a preparation method comprising the following steps:

[0056] Weigh 1.1977 g of magnesium powder and 4.0000 g of antimony powder, wash them in a glove box, seal the can, and use high-energy ball milling for 8 h at a speed of 1200 r / min and a ball-to-material ratio of 10:1 to obtain Mg3Sb2 powder.

[0057] The Mg3Sb2 powder was placed in a vacuum hot pressing sintering mold and the vacuum degree was adjusted to 6.0×10 -2 Pa, the sintering temperature is 600℃, the heating rate is 10℃ / min, the holding time is 2min, and the pressure holding time is 1.5h, and finally the bulk Mg3Sb2 material is obtained.

[0058] Then use 320-mesh and 2000-mesh sandpaper for coarse grinding and fine grinding in sequence to obtain p-type Mg3Sb2 semiconductor material.

[0059] Table 1: Density change table of Example 1

[0060]

[0061] Note: The theoretical density of Mg3Sb2 is 4.088 g cm -3

[0062] Table 1 is a table showing the density changes of the samples in Example 1. It can be seen from Table 1 that the density of the Mg3Sb2 semiconductor material prepared under the conditions of 8h high-energy ball milling and hot pressing at 600℃ and 60MPa is 4.05g / cm3 as measured by the Archimedean drainage method. 3 , which is about 99.07% of the theoretical density.

[0063] Figure 1 is the XRD pattern of the sample in Example 1. Figure 1 It can be seen that the sample has synthesized the main crystal phase Mg3Sb2, but there is a smaller secondary crystal phase Sb near 28°.

[0064] Figure 2 is the temperature-conductivity diagram of the sample in Example 1, from Figure 2 It can be seen that the conductivity of the sample can reach 3311S / m at around 773K.

[0065] Figure 3 is the SEM image of the sample in Example 1. Figure 3 It can be seen that the microscopic morphology of the sample has a tightly stacked layered structure, few surface defects, and a dense sample.

[0066] The above content is only for explaining the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A p-type Mg3Sb2 semiconductor material with high density and high conductivity, characterized in that: The relative density at room temperature is ≥99%, and the electrical conductivity reaches 3200-3400S / m at around 773K; The tightly stacked layered structure in the microscopic morphology of the p-type Mg3Sb2 semiconductor material constructs a conductive channel, conducts current transmission within and between layers, and improves carrier mobility.

2. A method for preparing a p-type Mg3Sb2 semiconductor material with high density and high conductivity, characterized in that: The following steps are included: Calculate and weigh the magnesium powder and antimony powder according to the molar ratio of Mg3Sb2, then load them into a ball mill, place the ball mill in the transition chamber of a glove box for air washing, fill the ball mill with argon in the glove box, and then quickly seal the ball mill. A p-type Mg3Sb2 semiconductor material with high density and high conductivity is obtained by mechanical alloying reaction using high-energy ball milling, hot pressing sintering, and sandpaper polishing.

3. The method for preparing a p-type Mg3Sb2 semiconductor material with high density and high conductivity according to claim 2, characterized in that: The purity of the magnesium powder is ≥99.5%, and the purity of the antimony powder is 99.9%; The purity of the argon gas is ≥99.999%.

4. The method for preparing a p-type Mg3Sb2 semiconductor material with high density and high conductivity according to claim 2, characterized in that: The ball milling conditions are as follows: the rotation speed of the ball mill is 1000-1500 r / min, the ball milling time is 6-10 hours, and the ball-to-material ratio is 10:1-15:

1.

5. The method for preparing a p-type Mg3Sb2 semiconductor material with high density and high conductivity according to claim 2, characterized in that: The current for hot pressing sintering is AC, the rated voltage of the hot pressing furnace is three-phase, 380V, 50Hz, and the rated power is 15KW.

6. The method for preparing a p-type Mg3Sb2 semiconductor material with high density and high conductivity according to claim 2, characterized in that: The vacuum degree of hot pressing sintering is 1.0×10 -2 Pa~8.0×10 -2 Pa; The sintering temperature of hot pressing sintering is 600-650° C., the sintering heating rate is 5-10° C. / min, and the holding time is 2-5 min.

7. The method for preparing a p-type Mg3Sb2 semiconductor material with high density and high conductivity according to claim 6, characterized in that: The heating and cooling process of hot pressing sintering is mainly divided into three stages. The first stage uses manual heating, with the voltage adjusted to 2~4V and the current adjusted to 0.3~0.5KA, from room temperature to 180℃~220℃; the second stage uses automatic heating, and continues to heat up to 580℃~620℃, and keeps warm for 2~5min; the third stage uses automatic cooling, using the machine's built-in circulating water cooling system to cool down, and the instrument is turned off when the temperature drops to 80℃~100℃.

8. The method for preparing a p-type Mg3Sb2 semiconductor material with high density and high conductivity according to claim 7, characterized in that: The sintering pressure is applied starting from 300℃~350℃, with a pressure growth rate of 2Mpa / min. When the temperature reaches 600℃, the pressure reaches 60Mpa, and then the pressure is maintained for 1~2h.

9. The method for preparing a p-type Mg3Sb2 semiconductor material with high density and high conductivity according to claim 2, characterized in that: The grinding conditions are as follows: firstly, using 280-500 mesh sandpaper for coarse grinding, and then using 2000-2500 mesh sandpaper for fine grinding.

10. Application of a p-type Mg3Sb2 semiconductor material with high density and high conductivity according to any one of claims 1 to 9, characterized in that: A p-type Mg3Sb2 semiconductor material with high density and high conductivity is used in infrared detectors, low-power magnetic storage, radiation detectors, self-powered sensors, and thermoelectric energy converters.

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