High oxygen pressures and the stabilization of the highest oxidation states of transition metals - Mössbauer spectroscopic characterization of the induced electronic phenomena

Abstract

High oxygen pressures are a fruitful tool for the stabilization of the highest formal oxidation states of transition metals (Mn+) leading to the strongest chemical bonds; the improvement of the Mn+-O bond covalency induces different electronic phenomena. Among the physical characterizations applied to investigate such phenomena, 57Fe and 119Sn Mössbauer spectra are evaluated for studying unusual electronic configurations, orbital ordering, charge disproportionation and insulator-metal transitions in the perovskites series of 57Fe doped RENiO3 nickelates (RE = rare earths, Y and Tl) and 119Sn doped AEFeO3 ferrates (AE = Ca, Sr). © 2006 Verlag der Zeitschrift für Naturforschung.