EPR, optical absorption amd microstructures of xV 2O 5.(1-x)As 2O 3 glasses

Abstract

EPR, optical absorption and electron microscopic investigation have been performed on xV 2O 5. (1-x)As 2O 3 glasses with O< x ⩽ 0.40. The EPR spectra are characteristic of the V 4+ ion with the 3d 1 electron localized on a single 51V(I = 7 2 ) nucleus in the glass network. The effect of the V 2O 5 content, of the parameters of the preparation process and of the heat treatment on the microvicinity of V 4+ is discussed. A correlation of EPR and optical data has been made using the molecular orbital (MO) theory. The values of MO coefficients indicate a high degree of covalency in the vanadium-oxygen bonds. The electron microscopic investigation reveals a glass-glass type phase separation in some of the samples.