Papers by Author: Soichiro Okamura

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Authors: Hiroaki Takeda, Soichiro Okamura, Tadashi Shiosaki
Authors: Hiroaki Takeda, C. Fujioka, Soichiro Okamura, Tadashi Shiosaki
Authors: Hiroaki Takeda, Shintaro Izukawa, Soichiro Okamura, Tadashi Shiosaki
Authors: Kazuya Komagata, Soichiro Okamura, Hiroaki Takeda, Tadashi Shiosaki
Authors: Kiyotaka Tanaka, Yoshinori Tsukamoto, Soichiro Okamura, Yutaka Yoshida
Abstract: sup>57Fe-enriched BiFeO3 (BFO) thin films were fabricated on SiO2/Si substrates from a stoichiometric precursor solution by chemical solution deposition process. The Bi/Fe molar ratio of the thin films decreased from 0.95 to 0.80 with increase in the sintering temperature. A perovskite phase and flat surface were obtained in the BFO thin films sintered at 500 and 600 °C. However, the 57Fe Mössbauer spectra showed a mixture phase due to amorphous and/or Bi2Fe4O9 phases in the BFO thin films. The valence state of Fe ions of the BFO thin films was confirmed to be only Fe3+ by the Mössbauer spectra.
Authors: Mitsumasa Nakajima, Takashi Fujisawa, Ken Nishida, Takashi Yamamoto, Minoru Osada, Hiroshi Naganuma, Soichiro Okamura, Hiroshi Funakubo
Abstract: (100)/(001)-oriented PZT thick films were grown on SrRuO3//(100) SrTiO3 and (100) MgO substrates by matel organic chemical vapor deposition (MOCVD) with different volume fraction of (001) orientation, and were compared with (001) single-oriented epitaxial PZT thick films grown on SrRuO3//LaNiO3//(100) CaF2 by polarized Raman spectroscopy. The spectra from (100)-oriented domain and (001)-oriented domain can be individually observed for the films with the mixture orientation of (100)/(001). Raman analysis revealed the different strain state of (100)-oriented and (001)-oriented domains. Moreover, the rotation dependence of A1(1TO) mode could be explained by the calculation using the volume fraction of (001)-oriented domains obtained from X-ray reciprocal space mapping analysis for the films with the mixture orientation of (100)/(001). These results suggest the local structure characterized by Raman spectroscopy almost agreed with the structure characterized by XRD analysis for the films with the mixture orientation of (100)/(001).
Authors: Kazuya Komagata, Hiroaki Takeda, Soichiro Okamura, Tadashi Shiosaki
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