联系人：王家成（69163661） 

　　报告摘要： 

　　Transition-metal oxides show lots of intriguing and useful properties. The wide variety of their crystal structures gives rise to various electronic structures, which lead to interesting physical and chemical properties. We are focusing on the fundamental physics and chemistry of such transition-metal oxides and seeking new materials with new functional properties. In searches for new oxide materials, we use high-pressure synthesis and epitaxial thin film growth in addition to the ordinary solid state reaction processes. These techniques open up possibility for getting new materials including meta-stable phases. 

　　In the presentation, we first focus on some ordered perovskite-structure oxides, in which transition-metal ions are included at the A and B sites in perovskite ABO₃ in ordered manners like A₂BB’O₆, AA’₃B₄O₁₂ and AA’₃B₂B’₂O₁₂. In these compounds, A-A, A-B, and B-B interactions compete and/or cooperate with each other and play important roles in giving rise to drastic changes in physical and chemical properties. Examples include the negative thermal expansion LaCu₃Fe₄O₁₂, and the half-metallic CaCu₃Fe₂Re₂O₁₂, both of which are prepared by high-pressure synthesis technique.  

　　The second topic focuses on the arrangement of oxygen ions at heterointerfaces of transition-metal oxide thin films. We have found significant modification of oxygen coordination at the interface between SrFeO_2.5 and DyScO₃. When the brown millerite-structure SrFeO_2.5 film grows epitaxially on a perovskite DyScO₃ substrate, the alternately ordered arrangement of oxygen is significantly disturbed and reconstructed in the heterointerface region to accommodate structural mismatch. The oxygen incorporation/release behaviors and possible oxide-ion conduction in the thin films will also be discussed. 

　　报告人简介: 

　　Prof. Yuichi Shimakawa is the Vice-Director of Institute for Chemical Research, Kyoto University, who focus on Solid state chemistry and Materials science. His scientific interests concern transition-metal oxides which show lots of interesting and useful properties. They include ferroelectrics, ferromagnets, conductors, batteries, and so on. The wide variety of their crystal structures gives rise to various electronic structures, which lead to interesting and useful physical and chemical properties. He is focusing on the fundamental physics and chemistry of these "functional oxides" and seeking new materials with new functions.