Precise Structure Analyses of Perovskite-type Mixed Conductors

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In this study, we aimed at 1) developing a neutron diffractometry under fuel cell operating conditions and a crystal structure evaluation method at a nuclear density level, and 2) elucidating the relationship between the crystal structure at a nuclear (or an electron) density level and the electrical conduction properties of perovskite-type mixed conductors. In fiscal 2005, (La,Sr)MnO_3-based perovskite-type compounds were synthesized and the following measurements were carried out: an X-ray absorption fine structure (XAFS) measurement (at National Institute of Advanced Industrial Science and Technology (AIST)), an X-ray diffraction measurement (at AIST), a high-temperature neutron diffraction measurement (at Tokai R&D center, Japan Atomic Energy Agency (JAEA)). In addition, a sample heating apparatus for high temperature neutron diffraction measurements has been designed and fabricated, and then a test run was carried out. In fiscal 2006, (La,Sr)CoO_3-based perovskite-type compounds w … More ere synthesized and the following measurements were carried out: in-situ synchrotron XAFS measurement (at Spring-8), in-situ X-ray diffraction measurement (at AIST), and in-situ neutron diffraction measurement using the heating apparatus developed in this project (at Tokai R&D center, JAEA). On the basis of analysis results of the measured data, we found close relationships between the crystal structures at nuclear (or electron) density level and the electrical conduction properties (oxide-ion and hole conductivities) of perovskite-type mixed conductors.In the future, we are planning to conduct in-situ neutron diffraction measurements using the new sample heating apparatus developed in this project for different kinds of fuel cell related materials. For the diffraction data obtained, we will make structure analyses at a nuclear density level, and elucidate its relationships with electrical conductivity systematically. We are also planning to open the research results on the WEB site "Solid-State Conductors Database for Electrochemical Devices (SSCED)" (URL http: //riodbdev.ibase.aist.go.jp/ssced/en/index.html) of the research information database (RIO-DB), AIST. Less