Mössbauer investigation of iron impurities in vitreous germanium selenide

Films of vitreous germanium selenide GeSe modified with iron impurities are investigated using 57Fe Mössbauer spectroscopy. It is found that, at low temperatures T < 295 K, the iron impurity centers are stabilized in three structurally nonequivalent positions, more specifically, the Fe3+ impurity centers are stabilized in octahedral and tetrahedral positions, whereas the Fe2+ impurity centers are stabilized in octahedral positions. At higher temperatures T > 295 K, the iron impurity centers located in octahedral and tetrahedral positions undergo a rapid electron exchange, which leads to the formation of an “averaged” iron state.