Evidence of multisite exchange in AgI–AgPO3 glasses: 109Ag NMR hole-burning spectra

A narrow 109Ag NMR spectrum of superionic conductor glass containing AgI exhibits strong broadening at low temperature or at low concentration of AgI. This broadening of the spectrum is attributed to the inhomogeneity of the local structure around Ag+ ions in the glass. The temperature and composition dependence of the spectra can be well explained by a multisite exchange (MSE) model. The existence of the local inhomogeneity and the exchange of Ag+ ions among them can be detected by site-selective hole-burning NMR technique. In this paper, the first measurement of the NMR hole-burning spectra of a superionic conductor glass of AgI–AgPO3 is reported. A clear hole is observed below −20 °C, which diffuses to the higher-frequency region corresponding to AgI-rich sites, where the exchange rate is faster. This technique is very useful to investigate site exchange of ions in disordered systems.