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Bismuth doping of induction furnace synthesized Mg2Si, Mg2Sn and Mg2Ge thermoelectric compounds
Intermetallics ( IF 4.4 ) Pub Date : 2020-05-01 , DOI: 10.1016/j.intermet.2020.106767
Meital Cahana , Yaniv Gelbstein

Abstract Silicides and especially Mg2X (X = Si, Sn, Ge) are considered as attractive thermoelectric materials, which are capable of an efficient heat to electricity energy conversion. They have low density, abundant and affordable raw constituents, and good mechanical properties. Yet, the synthesis of such Mg- based compounds is usually very challenging due to the reactivity, volatility and oxidation tendency of Mg. These challenges led many of the researchers exploring these materials, to low temperature synthesis routes, where, the most common is a solid-state mechanical alloying, using ball milling. In such synthesis approaches, Mg volatility was compensated upon the introduction of excess Mg into the source materials, beyond the stoichiometric composition. In the current research a novel synthesis route based on an induction melting in a closed Ta chamber is proposed. Using this technique undoped and Bi-doped Mg2X (X = Si, Sn, Ge) compounds were synthesized and analyzed. Phase separation into Mg2X- and Mg3Bi2-rich phases was observed for the Bi-doped compositions, with an associated significant reduction of the lattice thermal conductivity.

中文翻译:

感应炉铋掺杂合成Mg2Si、Mg2Sn和Mg2Ge热电化合物

摘要 硅化物,尤其是 Mg2X (X = Si, Sn, Ge) 被认为是有吸引力的热电材料,能够有效地将热能转化为电能。它们具有低密度、丰富且负担得起的原始成分以及良好的机械性能。然而,由于镁的反应性、挥发性和氧化倾向,这种镁基化合物的合成通常非常具有挑战性。这些挑战导致许多研究人员探索这些材料,采用低温合成路线,其中最常见的是使用球磨进行固态机械合金化。在这样的合成方法中,在超过化学计量组成的过量镁引入源材料后,镁挥发性得到补偿。在目前的研究中,提出了一种基于在封闭 Ta 室中感应熔化的新合成路线。使用这种技术合成和分析了未掺杂和掺杂 Bi 的 Mg2X(X = Si、Sn、Ge)化合物。对于掺杂 Bi 的组合物,观察到相分离成富含 Mg2X 和 Mg3Bi2 的相,伴随着晶格热导率的显着降低。
更新日期:2020-05-01
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