Development of synchrotron Mössbauer diffractometer and its possible application to industry

Mössbauer diffraction is a technique to measure a site-selective spectrum, which may enable us to obtain precise hyperfine parameters. The information about the electronic state, spin state, and local structure of constituent atoms will lead to fabricate novel materials and new functional materials. Here we review our development of a synchrotron ⁵⁷Fe Mössbauer diffractometer at BL11XU SPring-8 and its application to functional materials. In order to collect only the nuclear resonant scattering, which is relevant to a site-selective spectrum, we have proposed three methods: the 45º method, polarization analyzer method, and pure nuclear method. Thus, we have succeeded in obtaining the crystal-site-selective spectra of some multi-Fe-sites oxides, such as Fe₃O₄, Fe₃BO₆, and Y₃Fe₅O₁₂. At present, the apparatus is equipped by a four-circle diffractometer instead of the former θ-2θ goniometer, and has high sensitivity to measure the signals even from the natural iron specimens. In this paper, we also report our recent results on the crystal-site-selective spectra of the high temperature phase of Fe₃O₄, the examination of the charge ordered state of the low temperature phase of Fe₃O₄, and the crystal-site-selective spectra of Y₃Fe₅O₁₂.