EPR investigation and thermal study of yA2O-(1-y)[0.25(WO3)2-0.75(P2O5)] (A=Li, Na) glasses

Glasses belonging to the series yA(2)O-(1-y)[0.25(WO3)(2-)0.75P(2)O(5)] (y=0.10-0.60) are elaborated. DTA experiments reveal that the glass-network of the glasses are broken with increasing of modifier content. EPR spectra show the presence of two signals due to W5+ and Mo5+, as impuritie. The intensity of these EPR centres decreases when the concentration of A(2)O increases. The variation of T-g upon the modifier content is ascribed to structural changes occurring in the matrix of these glasses.