| Co-Investigator(Kenkyū-buntansha) |
YODA Yoshitaka Japan Synchrotron Radiation Research Institute, Materials Science Division, Dr. Researcher, 材料科学グループ, 副主幹研究員
TERAI Takayuki Graduate School of Engineering, Professor, 大学院・工学系研究科, 教授 (90175472)
SAWADA Tsuguo Graduate School of Frontier Sciences, Professor, 大学院・新領域創成研究科, 教授 (90011105)
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| Research Abstract |
1) The properties of YAP scintillation detector with fast response installed into new Mossbauer spectrometer were clarified.
2) Measurement system for ^<57>Fe Mossbauer resonant scintillation movable counter, was established. In the emission Mossbauer spectra (EMS), the efficiency of S/N was 400%. Even the 1/10 radioactivity of conventional source could be found to measure Mossbauer spectra with the better energy resolution than a conventional method.
3) Nuclear resonant inelastic scattering (NIS) was carried out in SPring 8 facility. It was confirmed that NIS spectra were obtained in 90 min using 8 detectors of APD with less than 1 ns time resolution. The program was developed for partial phonon density of states estimated from the nuclear inelastic scattering spectra. Lamb-Mossbauer factors at various temperatures, which are indispensable for quantitative analysis, were obtained from phonon density of states on the base of Debye model.
4) NIS spectra of various perovskite such as (Ba, Sr)(Fe, Co)O_<3-δ> and (Sr, Ca) (Fe,Co)O_<3-δ> were measured. It was found that the phonon peak of 8 meV was observed in brownmillerite with δ=0.5, but not in perovskite. NIS is very effective for analysis of the vibrational densities of states from 2 meV to 60 meV.
5) The surface and interface of stainless steel oxidized were characterized by selecting die electron energy using a conversion electron Mossbauer detector developed. It is found from the analysis of hyperfine distribution that the interface of ferrite stainless steel was affected by the diffusion of Cr to the surface. The stainless steel film as deposited by sputtering austenitic stainless steel was consisted of ferritic phase. The inner magnetic fields increased by heating., and the ferritic phase was converted into paramagnetic austenitic phase at 500℃. The states of thin oxide films with 10 nm in thickness produced at various temperatures were also estimated.
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