Mössbauer studies of microscopic disorder in solid electrolytes
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We implement for the first time Mössbauer Spectroscopy (MS) to investigate short-range properties of disorder in solid electrolytes. MS in129I and119Sn was carried out in RbAg4I5 and as impurity in Ag2Se, respectively. Measurements were performed both in the superionic and the normal phases. It is shown that localized cation hopping is an inherent feature of the α-AgI-type solid electrolytes. In RbAg4I5, at temperatures far belowTc, a small fraction of Ag is still locally mobile and atT>Tc, its concentration increases exponentially. A strong linear temperature dependence of the point-charge electric field gradient is observed and explained in terms of local hopping. With119Sn in Ag2Se we observe the onset of “local melting” of the Ag surrounding the SnSe4 cluster at 50 K below the bulk superionic phase transition. The characteristic features of MS related to microscopic studies of solid electrolytes are fully described.
KeywordsThin Film Phase Transition Characteristic Feature Microscopic Study Field Gradient
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