多元素掺杂优化SnTe的热电性能  

Optimization of Thermoelectric Properties of SnTe via Multi-element Doping

作　　者：苏浩健 周敏[1] 李来风[1] SU Haojian;ZHOU Min;LI Laifeng(Key Laboratory of Cryogenic Science and Technology,Technical Institute of Physics and Chemistry,Chinese Academy of Sciences,Beijing 100190,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院理化技术研究所,低温科学与技术重点实验室,北京100190 [2]中国科学院大学材料科学与光电技术学院,北京100049

出　　处：《无机材料学报》2024年第10期1159-1166,共8页Journal of Inorganic Materials

基　　金：低温科学与技术重点实验室课题(CRYO20230203);国家自然科学基金(51872299)。

摘　　要：热电材料可实现热能和电能的直接相互转换,在温差发电和半导体制冷领域具有广阔的应用前景。SnTe作为PbTe的无毒同族类似物,是一种极具潜力的中温区热电材料。本研究采用超重力场辅助燃烧合成(HG-CS)技术,结合放电等离子体烧结(SPS)制备多元素掺杂的SnTe基热电材料,系统研究了多元素掺杂对SnTe热电性能的影响规律和作用机制。在SnTe的阳离子位引入等价离子Ge^(2+)和Pb^(2+),阴离子位引入S^(2-)和Se^(2-),多元素掺杂引起大量晶格畸变点缺陷。同时,在超重力场下快速凝固带来的塑性变形引入了应力场和大量位错,从而形成了多级微观结构缺陷,强烈散射中高频声子,室温热导率从7.28 W·m^(-1)·K^(-1)(未掺杂SnTe)大幅下降到2.74 W·m^(-1)·K^(-1)(Sn_(0.70)Ge_(0.15)Pb_(0.15)Te_(0.80)Se_(0.10)S_(0.10)),在873 K时,其最小热导率仅为1.38 W·m^(-1)·K^(-1)。这些微结构缺陷散射声子的同时也散射载流子,导致载流子迁移率和电导率降低。值得一提的是,掺杂使SnTe的带隙减小,Seebeck系数提高,因此掺杂后材料的功率因子仍保持较高值。实验得到Sn_(0.70)Ge_(0.15)Pb_(0.15)Te_(0.80)Se_(0.10)S_(0.10)的最大热电优值(ZT)达到1.02(873 K),与未掺杂的SnTe相比得到大幅提高。Thermoelectric materials can realize the direct conversion of heat and electric energy,and have broad application prospects in the fields of thermoelectric power generation and semiconductor refrigeration.Both SnTe and PbTe thermoelectric materials belong to theⅣ-Ⅵgroup,and have the same NaCl-type crystal structure,but SnTe possesses poor thermoelectric properties.In this work,SnTe-based thermoelectric materials were prepared by a fast method,known as self-propagating high-temperature synthesis under high-gravity field(HG-CS)combined with spark plasma sintering(SPS).The effect and mechanism of multi-element doping on the thermoelectric properties of SnTe compounds were also studied.Multi-element doping,equivalent ions Ge^(2+)and Pb^(2+)in cation of SnTe and anionic S^(2-)and Se^(2-),causes a large number of lattice distortion point defects.At the same time,rapid solidification under the supergravity field brings about plastic deformation and introduces a stress field and a large number of dislocations,which results in the formation of multilevel microstructural defects and strong scattering of medium-and high-frequency phonons.As a result,the room-temperature thermal conductivity decreases dramatically from 7.28 W·m^(-1)·K^(-1)(undoped SnTe)to 2.74 W·m^(-1)·K^(-1)(Sn_(0.70)Ge_(0.15)Pb_(0.15)Te_(0.80)Se_(0.10)S_(0.10)),with a minimum thermal conductivity of only 1.38 W·m^(-1)·K^(-1) at 873 K.These microstructural defects scatter phonons and carriers,leading to a decrease in carrier mobility and conductivity.It is worth mentioning that doping decreases the bandgap of SnTe and increases the Seebeck coefficient,so that the power factor PF of the doped material remains at a high value.Finally,the peak thermoelectric figure of merit ZT of Sn_(0.70)Ge_(0.15)Pb_(0.15)Te_(0.80)Se_(0.10)S_(0.10) sample is greatly improved to 1.02(873 K).

关 键 词：碲化锡 热电材料 熵工程 超重力场辅助燃烧合成 

分 类 号：TB34[一般工业技术—材料科学与工程]