High-pressure synthesis of silicide thermoelectric material

近年来，热电材料的研究十分活跃，因为热电材料可以将余热回收为电能。硅化镁(Mg2Si)有望成为一种生态友好的半导体材料。我们利用高压(TP)技术研究了新型功能材料。在本研究中，我们在同步辐射装置上进行了高能X射线衍射仪，在活塞筒装置上进行了高能合成，并进行了热电测试。在此基础上，研制了小样品热电测量装置。HP-X射线衍射分析结果表明，在加压条件下，镁硅粉难以用镁替代银。镁、硅和银粉的混合物在镁的熔点以下反应。因此，将混合物用于HP合成，在1 GPa12小时内进行。热电测试结果表明，热压技术将使镁硅的导电类型由n型向本征转变。

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.