Improvement of Thermoelectric Properties and Development of Fabrication Processes for Environmental-friendly Half-Heusler Thermoelectric Materials

我们重点研究了半Heusler型化合物MniSn（M=Ti，Zr，Hf）作为环境友好的热电材料，它使我们的材料设计不依赖于有毒元素。MNiSn的热电性能作为其固有的物理性能进行评价，并且用相关的相平衡确定TiNiSn与ZrNiSn和HfNiSn的相分离，即相同的半Heusler有序结构之间的相分离。提出了基于Sn（液态）与TiNi（固态）反应以及SnO_2还原和Ti氧化的新制备工艺。研究了TiNiSn/Ti氧化物复合合金的热电性能。

We have focused on half-Heusler type compounds MNiSn (M=Ti, Zr, Hf) as environmental-friendly thermoelectric materials which allow us the materials design without depending on toxic elements. Thermoelectric properties of MNiSn were evaluated as their intrinsic physical properties, and the phase separation of TiNiSn from ZrNiSn and HfNiSn, i.e. between the same half-Heusler ordered structure, was determined with related phase equilibria. New fabrication processes were proposed based on the reaction between Sn (liquid) and TiNi (solid) as well as based on the reduction of SnO_2 and oxidization of Ti. Thermoelectric properties were evaluated for TiNiSn/Ti-oxides composite alloys.