Stabilization of elements in unusual oxidation states and temperature-reversible dynamics of electron pairs in oxide glasses. EPR-investigation

Abstract

Binary, three-component and multi-component borate, phosphate, germanate and silicate glasses, as well as barium-aluminophosphate glasses containing oxide of metals of (I–V) B groups, metals of the first transition series from titanium to nickel, niobium, tantalum, molybdenum and tungsten are investigated by EPR and optical spectroscopy at 77 and 300 K. The formation of metal ions in unusual oxidation states, such as Ag0, Zn1+, Cd1+, Hg1+, Ga2+, Tl2+, Ge3+, Sn3+, Pb3+, Sb4+, Bi4+, Nb4+, Ti3+, Ni1+, Mo5+, Cr3+, and Cr5+ was established. They were stabilized in the aforementioned glasses at specific compositions of components for an unlimited time at 300 K. It is shown that the reversible low temperature effect of disproportionation on atoms such as Nb, Ti, V, Mo, and W proves that in glass under ionizing gamma-radiation and temperature the reactions of disproportionation occur together with the reconstruction of conformation, the electron density transfer, the atomic displacement and the change (reversible or not) of a local structure of glass. It is shown that the formation of metal clusters in glass is connected with reaction of disproportionation.