摘要
固溶结合掺杂是优化材料热电性能的有效途径。本研究采用固相反应结合等离子体活化烧结成功合成了一系列单相的Mo1-xWxSeTe(0≤x≤0.5)固溶体及其Nb掺杂产物。热电输运研究表明,W固溶结合Nb掺杂显著提高了Nb2yMo0.5-yW0.5-ySeTe固溶体的载流子浓度、载流子迁移率、电导率和功率因子,适当降低了样品的晶格热导率,进而显著提高了材料的热电优值ZT。随着Nb掺杂量的增加,掺杂引入的离散能级转变为连续的杂质能带,同步提升了载流子浓度和载流子迁移率。取向性研究发现,由于在平行方向晶格热导率较低,Nb2yMo0.5-yW0.5-ySeTe固溶体在平行烧结压力方向的ZT略优。最优组分Nb0.03Mo0.485W0.485SeTe在垂直于烧结压力和平行于烧结压力方向获得了最高ZT,分别达到0.31和0.36(@823 K),是目前MoSe2基热电材料获得的最好结果之一。后续通过优化掺杂元素来改善Seebeck系数和功率因子,将有望进一步提升MoSe2基化合物的ZT。
Solid solutions forming and doping is an effective approach to optimize the transport properties of thermoelectric materials.In this study,a series of single-phase Mo1–xWxSeTe(0≤x≤0.5)solid solutions and their Nb-doped products were successfully synthesized with solid-state reaction followed by rapid sintering utilizing a Plasma Assisted Sintering apparatus.Thermoelectric transport studies showed that the carrier concentration,carrier mobility,electrical conductivity and power factor of the Nb2yMo0.5–yW0.5–ySeTe solid solutions were significantly increased by W substitution and Nb doping,while their lattice thermal conductivity was reduced,leading to remarkably enhanced dimensionless figure of merit ZT.The simultaneous increment of carrier density and carrier mobility with the increasing Nb content is due to the transition from discrete energy levels to continuous impurity band through Nb doping.The study of anisotropy indicated that,Nb2yMo0.5–yW0.5–ySeTe solid solutions owned a higher ZT value along the//P direction as a result of the lower lattice thermal conductivity.The Nb0.03Mo0.485W0.485SeTe compound presented the highest ZT values among all samples,which were 0.31 and 0.36(@823 K)along the^P and//P directions,respectively,representing one of the best results based on MoSe2-based materials.The enhancement of the Seebeck coefficient and the power factor is expected to further improve the ZT values of MoSe2-based compounds by optimizing the doping elements.
作者
周星圆
柳伟
张程
华富强
张敏
苏贤礼
唐新峰
ZHOU Xingyuan;LIU Wei;ZHANG Cheng;HUA Fuqiang;ZHANG Min;SU Xianli;TANG Xinfeng(State Key Laboratory of Advanced Technology for Materials Synthesis and Processing,Wuhan University of Technology,Wuhan 430070,China)
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2020年第12期1373-1379,I0006-I0008,共10页
Journal of Inorganic Materials
基金
国家自然科学基金(51702246,51632006)。
