摘要
晶粒细化是提高Bi_(0.5)Sb_(1.5)Te_(3)合金力学性能的有效途径,但是粉末冶金过程中晶粒细化导致的类施主效应会严重劣化材料热电性能,制约了Bi_(0.5)Sb_(1.5)Te_(3)基合金在微型热电器件中的应用。本研究围绕p型Bi_(0.5)Sb_(1.5)Te_(3)基合金,采用实验结合理论计算系统研究了粉末冶金制备过程中研磨和脱附气氛对烧结样品中类施主效应和电热输运性能的影响规律和机制。Bi_(0.5)Sb_(1.5)Te_(3)基合金破碎研磨过程中粉体表面产生缺陷V_(Te)^(··)和V_(Sb)^(")并物理吸附空气中的O_(2),在烧结过程中与吸附的O_(2)发生缺陷化学反应,产生大量V_(Te)空位和自由电子,导致类施主效应,使空穴浓度大幅降低。在保护气氛下(Ar气氛)研磨避免接触空气或在空气中研磨后放置在保护气氛下脱附O_(2),都可以有效抑制类施主效应,使样品保持较高的载流子浓度和电导率,且性能在473 K下保持稳定。在空气中研磨后直接烧结的样品和放置在空气中粉体烧结的样品表现出明显的类施主效应,样品的载流子浓度从保护气氛处理样品的4.49×10^(19)cm^(−3)下降至3.21×10^(19)cm^(−3),采用保护气氛处理的粉体烧结样品在402 K下获得最高的热电优值ZT为1.03,平均ZTave为0.92。该研究为调控p型多晶Bi_(2)Te_(3)基化合物的类施主效应和优化其热电性能提供了新思路。
Grain refinement is an effective way to improve the mechanical properties of Bi_(0.5)Sb_(1.5)Te_(3)based alloys.However,the donor-like effect caused by the grain refinement during powder metallurgy severely degrades the thermoelectric properties of the material,which limits the application of Bi_(0.5)Sb_(1.5)Te_(3)-based alloys in micro thermoelectric devices.Therefore,in this study,focusing on p-type Bi0.5Sb1.5Te3-base alloy,the impact of grinding and desorption atmosphere on donor-like effect and thermoelectric transport properties of sintered samples during powder metallurgy process were systematically studied through experiments combined with theoretical calculations.Surface defects V_(Te)and V_(Sb),generated by the grinding process of Bi_(0.5)Sb_(1.5)Te_(3)-based alloy,reacts with the adsorbed O_(2)during sintering process.This generates a large number of V_(Te)vacancies and free electrons,leading to a donor-like effect and a significant decrease in carrier concentration.The use of protective atmosphere(Ar atmosphere)during grinding to avoid exposure to air or O_(2)desorption under protective atmosphere after grinding effectively suppresses the donor-like effect,maintaining high carrier concentration and electrical conductivity of the sample.Moreover,the performance is stable up to 473 K.The samples treated in air or sintered using powder placed in air exhibit a significant donor-like effect,and the carrier concentration decreases from 4.49×10^(19)cm^(–3)to 3.21×10^(19)cm^(–3).The maximum thermoelectric ZT of 1.03 is obtained at 402 K for the samples sintered with the powders treated under protective atmosphere,and the overall average ZTave reaches 0.92.This study provides a new avenue to regulate the donor-like effect of p-type polycrystalline Bi_(2)Te_(3)-based compounds and to optimize their thermoelectric properties.
作者
鲁志强
刘可可
李强
胡芹
冯利萍
张清杰
吴劲松
苏贤礼
唐新峰
LU Zhiqiang;LIU Keke;LI Qiang;HU Qin;FENG Liping;ZHANG Qingjie;WU Jinsong;SU Xianli;TANG Xinfeng(Longzhong Laboratory in Hubei Province,Xiangyang Demonstration Zone of Wuhan University of Technology,Xiangyang 441000,China;State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology,Wuhan 430070,China;Nanostructure Research Center,Wuhan University of Technology,Wuhan 430070,China)
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2023年第11期1331-1337,I0012,I0013,共9页
Journal of Inorganic Materials
基金
国家自然科学基金(52122108,51972256)
国家重点研发计划(2018YFB0703600)
湖北隆中实验室自主创新项目(2022ZZ-07)。
