Analysis of Ag K-EXAFS Data of Superionic α-AgI

Abstract

The EXAFS data of Ag K-absorption of superionic AgI obtained by Boyce et al. are analyzed in final-state momentum space to avoid occurrence of ambiguous artifacts frequently observed upon Fourier-transforming raw data into real space. For the analysis, the phase shift of X-ray excited photoelectrons is calculated theoretically by means of Hartree-Fock method. As a result of the analysis, it is concluded that the Ag ions in α-AgI locate at the d, h, and b sites with a ratio of occupation probabilities 7: 7: 1, respectively. The motion of Ag ions is strongly correlated with the vibration of anions and performs a jump-like diffusion among the 42 available sites.