熵工程提高(GeTe)_(x)(AgSb_(0.5)Bi_(0.5)Te_(2))_(1-x)的热电性能和显微硬度  

Entropy engineering enhances the thermoelectric performance and microhardness of(GeTe)_(1-x)(AgSb_(0.5)Bi_(0.5)Te_(2))_(x)

作　　者：钟锦璇 梁格格 成家回 敖伟琴 张朝华 李钧钦 刘福生 张胜楠 胡利鹏 Jinxuan Zhong;Gege Liang;Jiahui Cheng;Weiqin Ao;Chaohua Zhang;Junqin Li;Fusheng Liu;Shengnan Zhang;Lipeng Hu(College of Materials Science and Engineering,Shenzhen Key Laboratory of Special Functional Materials,Guangdong Research Center for Interfacial Engineering of Functional Materials,Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization,Institute of Deep Earth Sciences and Green Energy,Shenzhen University,Shenzhen 518060,China;Superconducting Materials Research Center,Northwest Institute for Nonferrous Metal Research,Xi’an 710016,China)

机构地区：[1]College of Materials Science and Engineering,Shenzhen Key Laboratory of Special Functional Materials,Guangdong Research Center for Interfacial Engineering of Functional Materials,Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization,Institute of Deep Earth Sciences and Green Energy,Shenzhen University,Shenzhen 518060,China [2]Superconducting Materials Research Center,Northwest Institute for Nonferrous Metal Research,Xi’an 710016,China

出　　处：《Science China Materials》2023年第2期696-706,共11页中国科学(材料科学(英文版)

基　　金：supported by the National Natural Science Foundation of China(52071218);Shenzhen Science and Technology Innovation Commission(20200731215211001 and 20200814110413001);Guangdong Basic and Applied Basic Research Foundation(2022A1515012492)。

摘　　要：作为一种材料基因特性的内禀属性,构型熵是材料基因组中一个新兴的指征因子.设计具有高构型熵的多组元热电材料,可以通过严重的晶格畸变显著降低晶格热导率,并通过提高晶体对称性改善塞贝克系数.然而,高构型熵也造成了载流子迁移率的恶化,从而限制了zT值的改善.本文通过在众所周知的(GeTe)_(1-x)(AgSbTe_(2))_(x),即TAGS合金中用Bi取代一半的Sb,设计了(GeTe)_(1-x)(AgSb_(0.5)Bi_(0.5)Te_(2))_(x),又称TABGS合金,以证明熵工程的有效性.鉴于TAGS合金的载流子平均自由程较低,已接近Mott-Ioffe-Regel极限,进一步的Bi置换和构型熵增加不会再损害载流子迁移率.此外,通过高构型熵抑制菱方-立方相变和降低的载流子浓度有助于大幅提高Seebeck系数.而且,AgSb_(0.5)Bi_(0.5)Te_(2)合金化诱导的多尺度微观结构和减小的声速有效地抑制了晶格热导率.因此,(GeTe)_(0.80)(AgSb_(0.5)Bi_(0.5)Te_(2))_(0.20)的最高zT值在723 K达到了1.60,300到773 K之间的平均zTave值达到了1.23.同时,由于固溶硬化其室温维氏硬度达到了2.21 GPa.这些结果强调了熵工程在提高热电性能方面的有效性,特别是对大量具有本征低载流子迁移率的材料而言.As an endogenous material genetic property,entropy is an emerging fingerprint factor in the material genome.By designing multicomponent thermoelectric materials with high configuration entropy,the lattice thermal conductivity can be significantly reduced via severe lattice distortion,and the Seebeck coefficient can be improved by enhancing the crystal symmetry.However,high entropy also causes the deterioration of carrier mobility,restraining the improvement of the dimensionless figure of merit zT.Herein,we design the(GeTe)_(1-x)(AgSb_(0.5)Bi_(0.5)Te_(2))_(x),aka TABGS alloys,via replacing half of the Sb by Bi in the well-known(GeTe)_(1-x)-(AgSbTe_(2))_(x),aka TAGS alloys,to attest the efficacy of entropy engineering.In view of the low carrier mean free path of TAGS alloys approaching to the Mott-Ioffe-Regel limit,further Bi substitution and increased configuration entropy cannot impair the carrier mobility any longer.In addition,the suppressed rhombohedral-cubic phase transition via high configuration entropy and the reduced carrier concentration contribute to the substantially improved Seebeck coefficient.Furthermore,the elicited multiscale microstructures and the decreased sound velocity upon AgSb_(0.5)Bi_(0.5)Te_(2)alloying effectively restrain the lattice thermal conductivity.As a result,(GeTe)_(0.80)(AgSb_(0.5)Bi_(0.5)Te_(2))_(0.20)achieves a high zT of 1.60 at 723 K and an average zTaveof 1.23 from 300 to 773 K.Meantime,its room-temperature Vickers hardness reaches 2.21 GPa due to solid solution hardening.These results highlight the efficacy of entropy engineering in enhancing the thermoelectric performance,especially for numerous materials with intrinsically low carrier mobility.

关 键 词：载流子迁移率 固溶硬化 热电性能 晶格热导率 晶体对称性 平均自由程 塞贝克系数 材料基因组 

分 类 号：TM912[电气工程—电力电子与电力传动]