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 yA2O-(1-y)[0.25(WO3)2-0.75P2O5] ( 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 A2O increases. The variation of Tg upon the modifier content is ascribed to structural changes occurring in the matrix of these glasses. [ABSTRACT FROM AUTHOR]