<sup>193</sup>Ir Synchrotron-Radiation-Based Mössbauer Spectroscopy for Ir Valence Disproportionation in Ca<sub>5</sub>Ir<sub>3</sub>O<sub>12</sub>
Satoshi Tsutsui, Hiroki Hanate, Yoshitaka Yoda, Kazuyuki Matsuhira
Abstract
Synchrotron-radiation-based (SR-based) Mössbauer spectroscopy for the 73 keV transition in 193Ir nuclei was successful. 193Ir SR-based Mössbauer spectra of Ca5Ir3O12, as well as those of Ir metal and IrO2 were measured. The results for Ir metal and IrO2 agree with those reported previously. On the other hand, the spectra of Ca5Ir3O12 exhibit temperature dependence. Differences in the observed spectra between 90 and 110 K reflect a change in electronic state at the Ir sites, which correlates with the phase transition reported at 105 K. The results reported in the present work also demonstrate that 193Ir SR-based Mössbauer spectroscopy is a powerful tool for investigating microscopic electronic states in Ir-containing compounds.