Phase stability and thermoelectric properties of TiCoSb-TiM2Sn (M = Ni, Fe) Heusler composites
Phase stability and thermoelectric properties of TiCoSb-TiM2Sn (M = Ni, Fe) Heusler composites
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DOI：
10.1016/j.jssc.2019.04.041
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发表时间：
2019-08
影响因子：
3.3
通讯作者：
M. Asaad;J. Buckman;Ronald I. Smith;J. Bos
中科院分区：
文献类型：
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作者：
M. Asaad;J. Buckman;Ronald I. Smith;J. Bos
Heusler复合材料作为一种通过降低晶格热导率和载流子过滤效应来提高热电优值（ZT）的新途径已经引起了人们的极大关注。本工作通过研究TiCoSb-TiM_2Sn（M = Ni，Fe）复合材料扩展了这一领域。所有端元都是稳定相，但没有观察到半和全Heusler相的干净分离。相反，对于M = Ni，Co亚晶格上的部分取代和n型掺杂发生，结合Ni 3Sn 2和全Heusler相的形成。对于M = Fe，在Co位点上发生取代，导致p型导电。中子粉末衍射数据的Rietveld分析表明，没有证据表明在空的四面体位置上存在金属，这表明没有嵌入式Heusler夹杂物。这两个系列的热电性能随组成系统地变化。对于n型（M = Ni）和p型（M = Fe）系列，最高测量功率因数S2/ρ均为0.8 mW m− 1 K − 2，导致ZT在713 K时为0.12。这项工作扩展了关于TiCoSb基Heusler复合材料的相稳定性和热电性能的知识。
Heusler composites have attracted significant attention as a new route towards improving the thermoelectric figure of merit (ZT) through reduction of the lattice thermal conductivity and carrier filtering effects. This work extends this field by investigating TiCoSb-TiM2Sn (M = Ni, Fe) composites. All end-members are stable phases but no clean segregation into half- and full-Heusler phases was observed. Instead, for M = Ni, partial substitution on the Co sublattice and n-type doping occurs, combined with the formation of Ni3Sn2and full-Heusler phases. For M = Fe, substitution on the Co site occurs, leading to p-type conduction. Rietveld analysis of neutron powder diffraction data reveals no evidence for the presence of metals on the vacant tetrahedral site, signalling the absence of embedded Heusler inclusions. The thermoelectric properties of both series vary systematically with composition. For both n-type (M = Ni) and p-type (M = Fe) series, the highest measured power factors S2/ρ ∼ 0.8 mW m−1K−2leading to ZT ∼ 0.12 at 713 K. This work extends knowledge regarding the phase stability and thermoelectric properties of TiCoSb-based Heusler composites.