THERMAL, ELECTRICAL AND XPS STUDIES OF AG2O-CENTER-DOT-TEO2-CENTER-DOT-P2O5 GLASSES

A series of silver ion conducting glasses have been synthesized by pro gressive replacement of P2O5 by TeO2 in the 0.50 Ag2O . 0.50[xTeO(2) . (1 - x)P2O5] system. A wide glass-forming region extending from x = 0 to x = 0.9 was found. The glass of composition corresponding to x = 0. 4 was found to have the highest T-g = 196.7 +/- 0.1 degrees C. The ion ic conductivity was found to increase by about two orders of magnitude with increase in TeO2 content. While sigma(25 degrees C) = (1.93 +/- 0.43) x 10(-6) S cm(-1), the electronic conductivity was found to be ( 3.11 +/- 0.14) x 10(-10) S cm(-1) for the composition 0.50Ag(2)O . 0.3 0TeO(2) . 0.20P(2)O(5). X-ray photoelectron spectroscopy studies of th ese glasses reveal information about the structural modifications lead ing to the creation of bridging oxygens and non-bridging oxygens. The detailed analysis of the Te 3d XPS spectrum of the binary and ternary systems shows the existence of different Te-based structural units lik e TeO4, TeO3-, TeO32- and Ag-Te bond. The results from the ternary sys tem suggest the unique role played by P2O5 in the conversion of TeO, u nits leading to the creation of Ag-Te bond and TeO32- units.