Substitution Versus Full-Heusler Segregation in TiCoSb
Substitution Versus Full-Heusler Segregation in TiCoSb
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DOI：
10.3390/met8110935
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发表时间：
2018-11
期刊：
影响因子：
2.9
通讯作者：
M. Asaad;J. Buckman;J. Bos
中科院分区：
文献类型：
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作者：
M. Asaad;J. Buckman;J. Bos
半赫斯勒热电材料是一种很有前途的热电材料，具有很大的组成灵活性。在这里，我们扩展工作的p型掺杂的TiCoSb使用丰富的元素。研究了标称p型电子计数为17.85的Ti0.7V0.3Co0.85Fe0.15Sb0.7Sn0.3样品。使用粉末冶金法制备的样品具有负的塞贝克值，S ≤ −120 µV K−1，而电弧熔化的成分是补偿半导体，S = −45至+30 µV K−1。热电响应的差异是由V（Co0.6Fe0.4）2Sn全Heusler和Sn相的偏析程度的变化引起的，其选择性地吸收V、Fe和Sn。偏析的微结构导致晶格热导率降低，在室温附近κlat = 4.5−7 W m−1 K−1。在800 K时，n型样品的功率因数最大，S2/ρ = 0.4 mW m−1 K−2，ZT = 0.06。该工作扩展了关于TiCoSb合适的p型掺杂剂的知识。
Half-Heuslers (HHs) are promising thermoelectric materials with great compositional flexibility. Here, we extend work on the p-type doping of TiCoSb using abundant elements. Ti0.7V0.3Co0.85Fe0.15Sb0.7Sn0.3 samples with nominal 17.85 p-type electron count were investigated. Samples prepared using powder metallurgy have negative Seebeck values, S ≤ −120 µV K−1, while arc-melted compositions are compensated semiconductors with S = −45 to +30 µV K−1. The difference in thermoelectric response is caused by variations in the degree of segregation of V(Co0.6Fe0.4)2Sn full-Heusler and Sn phases, which selectively absorb V, Fe, and Sn. The segregated microstructure leads to reduced lattice thermal conductivities, κlat = 4.5−7 W m−1 K−1 near room temperature. The largest power factor, S2/ρ = 0.4 mW m−1 K−2 and ZT = 0.06, is observed for the n-type samples at 800 K. This works extends knowledge regarding suitable p-type dopants for TiCoSb.