Development of Magnetoelectric and Thermoelectric Devices Using Functionally Separated Nano Structures in Clathrate Compounds

本研究合成了多种笼形化合物，并对其热电性能和磁性能进行了研究。对于热电笼形化合物，p-Ba_8 Ga_ySn_ Ge_x（ZT=1.2）具有较高的无量纲热电优值<46-x-y>。本文根据第VIII型Ba_8Ga_Sn_3单晶和多晶的霍尔测量结果，讨论了载流子输运现象<16><30>。对于磁性包合物，IBa_8Fe_yGa_xGe_2和<46-x-y>III型Ba_6Fe_1Ga_xGe_3<24-x>表现出铁磁行为，居里温度达到室温，高于文献报道的居里温度。TC依赖于载流子浓度，这种载流子浓度依赖性可以用RKKY机制解释。我们还制备了这些笼形物的铁磁薄膜。

In this study, many kinds of clathrates were synthesized, and their thermoelectric and magnetic properties were investigated. For thermoelectric clathrates, their high values of the dimensionless thermoelectric figure of merit were obtained for p-Ba_8Ga_ySn_<46-x-y>Ge_x(ZT=1.2). The carrier transport phenomena were considered based on the results of Hall measurements of single- and poly-crystals of type-VIII Ba_8Ga_<16>Sn_<30>. For magnetic clathrates, type-IBa_8Fe_yGa_xGe_<46-x-y> and type-III Ba_6Fe_1Ga_xGe_<24-x> showed the ferromagnetic behavior, and their Curie temperature TC reached to room temperature, which was higher than the reported TC. The TC depended on the carrier concentration, and this carrier concentration dependence could be explained by the RKKY mechanism. We also prepared the ferromagnetic films of these clathrates.