n型Pb_(1+x)SeTe_(x)固溶体的自蔓延高温合成及热电性能调控

Enhanced Thermoelectric Performance of n-Type Pb_(1+x)SeTe_(x) Prepared by Self-Propagating High Temperature Synthesis

热电材料能实现热能与电能之间的直接转化,因而受到广泛关注。铅基硫属化合物是一类具有较高热电转化效率的材料,其中,PbSe和PbTe是这类材料的代表。与Te相比,Se元素的地壳丰度高、成本低,所以PbSe更具研究价值和应用潜力。但PbSe的晶格热导相对较高,载流子浓度较低,抑制了热电性能的提升。而固溶能有效降低晶格热导率,提升热电性能,且PbTe和PbSe具有相似的能带结构,能简化输运研究,因此将PbTe与PbSe固溶,有望获得较高的热电性能。另外,在目前的研究中,PbSe的合成通常采用机械合金化、熔融退火等方式,耗费大量的时间和能量,生产成本高,不利于实际使用。本文使用自蔓延高温合成与放电等离子体烧结相结合的方式,快速制备了n型Pb_(1+x)SeTe_(x)固溶体。同时,由于载流子浓度的优化及合金散射的作用,电学性能和热学性能得到了提升,晶格热导率在773 K时降低到0.67W/(m·K),相较于纯PbSe降低了35%,无量纲优值ZT值在773 K时达到了1.1,相较于纯PbSe提升了83%。以上研究为自蔓延制备工艺在热电领域的广泛应用提供了参考。

Thermoelectric materials have attracted much attention because they can realize the direct conversion between heat and elec⁃tric energy.Lead-based sulfur compounds are a class of materials with high thermoelectric conversion efficiency,and PbSe and PbTe are the representatives of this class of materials.Compared to PbTe,PbSe has more significant research value and application potential due to the higher abundance and lower cost of Se.However,its relatively high lattice thermal conductivity and low carrier concentration restrain the thermoelectric performance of PbSe.Forming solid solution can effectively reduce the lattice thermal conductivity and im⁃prove the thermoelectric properties.Besides,the energy band structure of PbTe and PbSe is similar,which can simplify the transport re⁃search.Therefore,the solid solution of PbTe and PbSe is expected to obtain higher thermoelectric properties.Current synthesis methods of PbSe,such as mechanical alloying and melt annealing,require substantial time and energy,leading to high production costs,which are not conducive to practical use.In this paper,n-type Pb_(1+x)SeTe_(x) solid solutions were rapidly prepared by combining self-propagating high-temperature synthesis(SHS)with spark plasma sintering(SPS).Due to the optimization of carrier concentration and the effect of al⁃loy scattering,both electrical and thermal properties were improved.The lattice thermal conductivity reduced to 0.67 W/(m·K)at 773 K,which was 35% lower than that of pure PbSe,and figure of merit(ZT)value reached 1.1 at 773 K,which was 83% higher than that of pure PbSe.This work provided a reference for the wide application of self-propagating preparation technology in thermoelectric field.