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CN-121976074-A - MgH is adopted2Quick preparation of high-performance n-type Mg by using powder instead of Mg powder3Sb2Method for preparing thermoelectric material

CN121976074ACN 121976074 ACN121976074 ACN 121976074ACN-121976074-A

Abstract

The invention relates to the technical field of new energy materials, in particular to a method for rapidly preparing a high-performance n-type Mg 3 Sb 2 -based thermoelectric material by adopting MgH 2 powder instead of Mg powder, wherein MgH 2 , sb and Te powder are poured into a mortar for manual grinding and fully mixed. And filling the obtained mixed powder into a graphite mold, and then adopting a Spark Plasma Sintering (SPS) technology to obtain the bulk Mg 3.5 Sb 1.97 Te 0.03 thermoelectric material. The Mg 3.5 Sb 1.97 Te 0.03 thermoelectric material prepared by introducing MgH 2 powder to replace Mg powder reduces the oxidation of Mg element, so that the conductivity of the thermoelectric material is obviously increased. The hydrogen decomposed by MgH 2 during sintering causes holes to appear in the sample, and in addition, excessive MgH 2 remains MgO nano particles which are uniformly dispersed after the grain boundary enrichment and decomposition. Holes in the sample and a large number of nano particles dispersed on the grain boundary enhance phonon scattering and obviously reduce lattice thermal conductivity. As a result, the Mg 3.5 Sb 1.97 Te 0.03 thermoelectric material prepared using MgH 2 powder as a raw material obtained a high ZT value of 1.60 at 800K, which was significantly higher than the Mg 3.5 Sb 1.97 Te 0.03 thermoelectric material prepared using Mg powder as a raw material.

Inventors

  • LIU ZHIYUAN
  • ZHA JIAWEI
  • ZHAO XIANGWEI
  • XIA AILIN

Assignees

  • 安徽工业大学

Dates

Publication Date
20260505
Application Date
20260210

Claims (5)

  1. 1. A method for rapidly preparing a high-performance n-type Mg 3 Sb 2 -based thermoelectric material by adopting MgH 2 powder to replace Mg powder is characterized by comprising the following steps: s1, grinding MgH 2 , sb and Te, fully mixing, and then filling into a graphite mold; S2, sintering the mixed powder filled in the graphite die in the step S1 under vacuum by adopting a discharge plasma sintering method to obtain the n-type Mg 3 Sb 2 -based thermoelectric material.
  2. 2. The method for rapidly preparing the high-performance n-type Mg 3 Sb 2 -based thermoelectric material by using MgH 2 powder instead of Mg powder according to claim 1, wherein in the step S1, the amounts of MgH 2 , sb and Te are weighed according to the nominal composition Mg 3.5 Sb 1.97 Te 0.03 .
  3. 3. The method for rapidly preparing the high-performance n-type Mg 3 Sb 2 -based thermoelectric material by adopting MgH 2 powder to replace Mg powder according to claim 1, wherein in the step S1, the grinding time is 15-20 min, and the grinding method is manual grinding.
  4. 4. The method for rapidly preparing the high-performance n-type Mg 3 Sb 2 -based thermoelectric material by using MgH 2 powder instead of Mg powder according to claim 1, wherein in the step S2, the vacuum condition is that the vacuum degree is less than 0.1MPa.
  5. 5. The method for rapidly preparing the high-performance n-type Mg 3 Sb 2 -based thermoelectric material by adopting MgH 2 powder to replace Mg powder according to claim 1, wherein in the step S2, the sintering temperature is 795-800 ℃, the sintering pressure is uniaxial pressure 50-60 MPa, and the sintering time is 5-10 min.

Description

Method for rapidly preparing high-performance n-type Mg 3Sb2 -based thermoelectric material by adopting MgH 2 powder to replace Mg powder Technical Field The invention relates to the technical field of new energy materials, in particular to a method for rapidly preparing a high-performance n-type Mg 3Sb2 -based thermoelectric material by adopting MgH 2 powder to replace Mg powder. Background In the global energy crisis background, the development of new energy is urgent. The thermoelectric material is a new energy functional material which realizes the mutual conversion between heat energy and electric energy by utilizing thermoelectric physical effect (Seebeek, peltier and Thomson effect). Compared with the traditional heat engine, the device made of the thermoelectric material has the advantages of no mechanical transmission part, no pollution, no noise, no vibration, small space occupation rate and the like, and plays an important role in the future energy utilization and thermal management. Especially has wide application prospect in the thermoelectric refrigeration and power generation fields. The conversion efficiency of thermoelectric materials is generally measured by dimensionless thermoelectric figure of meritTo evaluate the number of the groups of groups,WhereinFor the electrical conductivity of the material,For the Seebeck coefficient,The temperature is set to be the absolute temperature,Is the thermal conductivity. Wherein the method comprises the steps ofBy thermal conductivity of charge carriersAnd lattice thermal conductivityTwo-part composition. The ideal thermoelectric material should have a high electrical conductivity, a Seebeck coefficient, and a low thermal conductivity. However、AndThe three parameters are strongly coupled due to a scattering mechanism and an energy band structure, so that the three parameters are strongly associated with each other, and the cooperative regulation and control of the three parameters to further improve the zT value are hot spots of the basic research of the current thermoelectric materials. The Zintl phase compound is a crystal material composed of electropositive metal and electronegative metalloid/nonmetal, and is characterized in that the Zintl phase compound is a complex chemical bond network formed by a negative and positive ion framework, and has the characteristic of phonon glass-electron crystal (PGEC). Therefore, among the numerous thermoelectric materials, there is a great deal of attention from researchers. Mg 3Sb2 -based thermoelectric material is a typical Zintl-phase thermoelectric compound, has an inverse alpha-La 2O3 rhombohedral structure (space group: P3m 1), and is of great interest in the thermoelectric material in the medium temperature region due to its unique layered crystal structure, proper forbidden bandwidth and intrinsically low thermal conductivity. In the preparation of Mg 3Sb2 -based thermoelectric materials, oxidation of Mg has been a key factor in impeding the performance enhancement. Therefore, how to reduce the oxidation of Mg during sample preparation is a key challenge in enhancing Mg 3Sb2 -based thermoelectric materials. In addition, the traditional method for preparing the Mg 3Sb2 -based thermoelectric material needs long-time ball milling, and has longer preparation period and high cost. In view of the above drawbacks, the present inventors have finally achieved the present invention through long-time studies and practices. Disclosure of Invention The invention aims to solve the problem of how to reduce the oxidation of Mg in the preparation process of Mg 3Sb2 -based thermoelectric materials, and provides a method for rapidly preparing high-performance n-type Mg 3Sb2 -based thermoelectric materials by adopting MgH 2 powder to replace Mg powder at a lower sintering temperature. In order to achieve the above purpose, the invention discloses a method for rapidly preparing a high-performance n-type Mg 3Sb2 -based thermoelectric material by adopting MgH 2 powder to replace Mg powder, which comprises the following steps: s1, grinding MgH 2, sb and Te, fully mixing, and then filling into a graphite mold; S2, sintering the mixed powder filled in the graphite die in the step S1 under vacuum by adopting a discharge plasma sintering method to obtain the n-type Mg 3Sb2 -based thermoelectric material. In the step S1, the amounts of MgH 2, sb and Te are weighed according to the nominal composition Mg 3.5Sb1.97Te0.03. In the step S1, the grinding time is 15-20 min, and the grinding method is manual grinding. In the step S2, the vacuum condition is that the vacuum degree is less than 0.1MPa. In the step S2, the sintering temperature is 795-800 ℃, the sintering pressure is uniaxial pressure of 50-60 MPa, and the sintering time is 5-10 min. Compared with the prior art, the invention has the beneficial effects that the invention utilizes the characteristic that MgH 2 powder is not easy to oxidize compared with Mg powder under the sa