Analysis of Electron Conduction Band of Electro-conductive Ceramics by X-ray Absorption

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Electron conduction bands of electro-conductive ceramics, such as MgIn_2O_<4-delta> and BaPb_<1-x>Bi_xO_<3-delta>, were analyzed mainly by X-ray absorption. The former is the newly discovered transparent conductor, and the latter is classical superconducting oxide.1. Transparent thin film of MgIn_2O_<4-delta> was successfully prepared for the first time. Large progress not only for application but for fundamental research could be made.2. X-ray absorption of the thin film of MgIn_2O_<4-delta> was measured and pre-edge peak was observed in In-L absorption edge. It was revealed that conduction band consisted mainly of In 5s orbital.3. Relationship between crystal structure and electronic conduction behavior of BaPb_<1-x>Bi_xO_<3.00> was revealed by X-ray diffraction and electron conduction measurement. Measured X-ray absorption spectroscopy consisted with electronic structure of conduction band, which was deduced from the above clarified relationship.4. In order to clarify the influence … More of oxygen deficiency on electronic band structure of BaPb_<0.75>Bi_<0.25>O_<3-delta>, X-ray absorption spectroscopes were measured on the samples with various oxygen deficiency, delta. There were little variation in line shape of X-ray absorption by delta, which suggested that variations of electron carrier concentration and orbitals which composed the conduction band were negligible.5. Besides X-ray absorption, thermobalance, electronic conduction at high temperature and Seebeck coefficient of BaPb_<0.75>Bi_<0.25>O_<3-delta> were measured. It was revealed that oxygen deficiency worked as scattering center rather than electron carrier generation. These results consisted with that of X-ray absorption spectroscopy.6. Coexistence of electrons with large mobility and holes with low mobility in BaPb_<0.75>Bi_<0.25>O_<3-delta> was revealed from the measurement of temperature dependence of Seebeck coefficients. This information might be useful for the analysis of superconducting transition mechanism. Less