High-pressure synthesis of silicide thermoelectric material

近年来，热电材料由于能够将废热能回收为电能而得到了积极的研究。硅化镁（Mg_2Si）是一种环境友好的半导体材料。我们利用高压（TP）技术研究了新型功能材料。在本研究中，我们利用同步辐射装置进行了高压X射线衍射（XRD），利用活塞圆筒装置进行了高压合成，并进行了热电测量。HP-XRD研究结果表明，Mg_2Si粉末在加压条件下很难用Mg取代Ag。Mg、Si和Ag粉末的混合物在低于Mg的熔点下反应。因此，将该混合物用于在IGPa下HP合成12小时。热电性能测试结果表明，HP技术可以使Mg_2Si的导电类型由n型转变为本征型。

Recently thermoelectric material has been studied actively because the material can recover waste heat energy as electric energy. Magnesium silicide (Mg2Si) is expected as an ecological friendly semiconductor. We have researched new functional material by using high-pressure (TP) technique. In this study, HP X-ray diffraction (XRD) at synchrotron radiation facility, HP synthesis by using piston cylinder equipment, and thermoelectric measurement were performed. Furthermore the equipment of thermoelectric measurement for small samples was developed.The result of HP-XRD study suggested it is difficult for the powder of Mg2Si to replace Ag with Mg under pressure. A mixture of Mg, Si, and Ag powders were reacted below melting point of Mg. Therefore, the mixture were used in the HP-synthesis at 1 GPa for 12 hrs. The result of thermoelectric measurements expects HP technique advance the conduction type of Mg2Si from n-type to intrinsic.