Toshihiro Okajima

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The properties of ceramic materials are strongly influenced by the presence of ultradilute impurities (dopants). Near-edge X-ray absorption fine structure (NEXAFS) measurements using third-generation synchotron sources can be used to identify ultradilute dopants, provided that a good theoretical tool is available to interpret the spectra. Here, we use(More)
Proton-coupled electron-transfer oxidation of a Ru(II) -OH2 complex, having an N-heterocyclic carbene ligand, gives a Ru(III) -O(.) species, which has an electronically equivalent structure of the Ru(IV) =O species, in an acidic aqueous solution. The Ru(III) -O(.) complex was characterized by spectroscopic methods and DFT calculations. The oxidation state(More)
In this study, we focused on the origin on the selective deposition of rutile and anatase TiO2 thin films during the sputtering process. The observation on microstructural evolution of the TiO2 films by transmission electron microscopy revealed the coexistence of rutile and anatase TiO2 phases in the initial stage under the preferential growth conditions(More)
The thermal stability and dielectric and structural properties of ferroelectric Ba1-xCaxTi2O5 (0 ≤ x ≤ 0.30) prepared by crystallization from glass are investigated. The Ba1-xCaxTi2O5 compounds with x < 0.10 are thermally stable phases, while those with x ≥ 0.10 are metastable phases. The ferroelectric transition temperature drastically decreases from 470(More)
Three types of functional ceramic materials, (1) dilute magnetic semiconductor, (2) phosphor and (3) electrolyte of a solid fuel cell, are fabricated by the conventional solid state reaction method. Local environments of dopants in these ceramic materials here synthesized are systematically investigated by using the x-ray absorption near-edge structure(More)
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