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CN-121974696-A - In-situ composite BiCuSeO-based thermoelectric material and preparation method thereof

CN121974696ACN 121974696 ACN121974696 ACN 121974696ACN-121974696-A

Abstract

The invention discloses an in-situ composite BiCuSeO-based thermoelectric material and a preparation method thereof, belonging to the technical field of new energy conversion. And (3) weighing Bi 2 O 3 , bi, cu, se and PbO high-purity powder raw materials according to the stoichiometric ratio of BiCu 0.95 Pb x Se 1+x O (x is more than 0 and less than or equal to 0.03), grinding and mixing uniformly, vacuum packaging into a quartz tube for high-temperature solid-phase synthesis reaction, grinding the obtained ingot product into powder, filling into a graphite mold, and carrying out vacuum hot-pressing sintering to obtain a high-density block body, thereby obtaining the in-situ composite BiCuSeO-based thermoelectric material. The in-situ composite BiCuSeO-based thermoelectric material prepared by the invention can generate PbSe in situ in a matrix, effectively improve carrier concentration and mobility, optimize electrical conductivity and power factor, and simultaneously maintain thermal conductivity by in-situ composite PbSe, thereby improving final thermoelectric performance. The invention provides a good method for in-situ compounding and performance optimization of thermoelectric materials.

Inventors

  • LI ZHOU
  • XU QING
  • SONG JIMING
  • WANG SHUJUN
  • QIAN JUN
  • FANG XIANXIAN
  • GAO YAN
  • ZHOU WEI
  • WANG FAN

Assignees

  • 安徽大学

Dates

Publication Date
20260505
Application Date
20260309

Claims (7)

  1. 1. The in-situ composite BiCuSeO-based thermoelectric material is characterized by having a chemical general formula of BiCu 0.95 Pb x Se 1+x O, wherein BiCu 0.95 SeO is a base material, pbSe is a composite phase generated in situ, x represents the atomic ratio of the PbSe composite phase, and the value range is 0< x less than or equal to 0.03.
  2. 2. The in-situ composite BiCuSeO-based thermoelectric material according to claim 1, wherein when x is 0.005,0.01,0.03, namely the specific chemical formula of the in-situ composite BiCuSeO-based thermoelectric material is BiCu 0.95 Pb 0.005 Se 1.005 O、BiCu 0.95 Pb 0.01 Se 1.01 O、BiCu 0.95 Pb 0.03 Se 1.03 O, the electric conductivity is 4439-14270S m -1 , the Seebeck coefficient is 204-327 mu V K -1 , the power factor is 4.33-6.57 mu W cm -1 K -2 , the thermal conductivity is 0.41-0.98W m -1 K -1 , and the thermoelectric figure of merit is 0.17-1.29.
  3. 3. The in-situ composite BiCuSeO-based thermoelectric material according to claim 2, wherein the in-situ generated PbSe composite phase can effectively optimize carrier transport performance of a matrix, improve power factor and thermoelectric figure of merit, and compared with the BiCu 0.95 SeO base material, the in-situ composite PbSe BiCuSeO-based thermoelectric material has a room temperature carrier concentration increased from 7.36×10 18 cm -3 to 2.15×10 20 cm -3 and a room temperature carrier mobility increased from 3.38 cm 2 V -1 S -1 to 5.20 cm 2 V -1 S -1 and a room temperature carrier mobility increased from 3.38 to 54%, a maximum power factor increased from 4.49 μW cm -1 K -2 to 6.57 μW cm -1 K -2 in a range of 30-600 ℃, and a maximum ZT value increased from 0.75 to 1.29 in a range of 30-600 ℃ and a room temperature carrier mobility increased by 72%.
  4. 4. The in-situ composite BiCuSeO-based thermoelectric material according to claim 2, wherein the in-situ composite BiCuSeO-based thermoelectric material having the largest thermoelectric figure of merit has a chemical formula of BiCu 0.95 Pb 0.01 Se 1.01 O.
  5. 5. A method for preparing the in-situ composite BiCuSeO-based thermoelectric material according to any one of claims 1 to 4, comprising the steps of: (1) Weighing required Bi 2 O 3 , bi, cu, se and PbO raw materials according to the stoichiometric ratio of BiCu 0.95 Pb x Se 1+x O, fully grinding, vacuum packaging the ground and mixed raw material powder in a quartz tube for high-temperature solid-phase reaction to obtain an ingot product; (2) Grinding the ingot product obtained in the step (1) into powder, filling the powder into a graphite mold, and performing vacuum hot-pressing sintering to obtain the in-situ composite BiCuSeO-based thermoelectric material.
  6. 6. The method for preparing the in-situ composite BiCuSeO-based thermoelectric material according to claim 5, wherein the high-temperature solid phase reaction in the step (1) adopts a two-stage sintering process, namely, one-stage heating to 250-400 ℃, heat preservation for 650-800 min, and two-stage heating to 650-800 ℃ and heat preservation for 500-600 min.
  7. 7. The method for preparing the in-situ composite BiCuSeO-based thermoelectric material according to claim 5, wherein the vacuum hot-pressing sintering in the step (2) adopts a pressurizing-before-heating process, namely, axial pressure is firstly increased to 70-90 MPa at room temperature, then pressure is maintained and heated to 500-700 ℃, then the pressure is maintained and kept for 20-30 min, and finally, pressure is released and natural cooling is carried out to room temperature.

Description

In-situ composite BiCuSeO-based thermoelectric material and preparation method thereof Technical Field The invention belongs to the field of thermoelectric materials, and particularly relates to an in-situ composite BiCuSeO-based thermoelectric material and a preparation method thereof. Background Under the background that the global energy demand continues to increase and the environmental problem is increasingly severe, the thermoelectric material is used as a functional material capable of directly realizing the mutual conversion of heat energy and electric energy, and based on the Seebeck effect and the Peltier effect, the thermoelectric material has great application potential in the fields of industrial waste heat recovery, solid refrigeration, deep space exploration and the like, and has great significance in relieving energy crisis and reducing environmental pollution. The performance core of the thermoelectric material is measured by a thermoelectric figure of merit ZT, and the calculation formula is zt=s 2 σt/κ, where S is the seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity. To realize efficient thermoelectric conversion, the high seebeck coefficient, the high electrical conductivity and the low thermal conductivity are considered at the same time, but the mutual coupling relation exists among the three parameters, and how to realize the cooperative optimization of the three parameters is one of the core research difficulties in the field of the current thermoelectric materials. At present, the commercial thermoelectric material is mainly Bi2Te 3-based material, but Te element reserves are scarce, the cost is higher, the brittleness is large, and the large-scale application and scene expansion of the material are limited, so that the development of novel low-cost and high-performance thermoelectric material becomes urgent need of industry. BiCuSeO, which has been widely paid attention to as a novel oxide thermoelectric material since 2010, has a unique superlattice layered structure, and [ Bi 2O2]2+ layers and [ Cu 2Se2]2- layers are alternately arranged, and the structure gives the excellent intrinsic characteristics that the layered structure restricts electron movement so that the layered structure has a higher Seebeck coefficient, and that the interlayer weak interaction enhances phonon scattering so as to effectively reduce lattice thermal conductivity. Meanwhile, the material has the advantages of good chemical stability, low cost, environmental friendliness and the like, and is an ideal candidate material for thermoelectric application in a medium-high temperature area. However, the thermoelectric performance of the pure-phase BiCuSeO still cannot meet the practical application requirements, and the carrier mobility is low, the conductivity is insufficient, so that the thermoelectric figure of merit ZT is limited in improvement. In order to optimize the thermoelectric performance of BiCuSeO, the prior art mainly adopts strategies such as element doping, compounding and the like, wherein the compounding can simultaneously regulate and control electric transmission and phonon transmission, and the method becomes one of the most effective performance optimization means. PbSe is used as a traditional IV-VI semiconductor thermoelectric material, has high carrier mobility, adjustable conductivity type and good electric transmission performance, does not contain rare element Te, has relatively low cost, and is an ideal composite modified component. At present, research is attempted to compound and modify BiCuSeO and PbSe, but the existing compound method is mainly carried out after physical mixing and sintering, and belongs to non-in-situ compounding, and the preparation method has the defects that firstly, the interface compatibility of two components is poor, the phase separation phenomenon is easy to occur, the stable interface combination cannot be formed, the carrier is seriously scattered at the interface, the electric transmission efficiency is reduced, secondly, the uniform dispersion of PbSe in a BiCuSeO matrix is difficult to realize through physical mixing, the synergistic effect of the two components cannot be fully exerted, the carrier concentration or the mobility of a material is difficult to effectively improve, thirdly, the preparation process is complicated through multi-step high-temperature treatment, the energy consumption is high, the defects of the material are easy to occur, and the thermoelectric performance and the mechanical performance are further influenced. Therefore, developing a BiCuSeO and PbSe composite technology capable of solving the above problems has become a key to push BiCuSeO-based thermoelectric materials to practical applications. Disclosure of Invention The invention aims to solve the technical problem of providing an in-situ composite BiCuSeO-based thermoelectric material aiming at