Synthesis and characterization of silver borotellurite glasses

Abstract

The glass transition temperature, Tg; density, ρ; ionic conductivity, σi and X-ray photoelectron spectroscopy (XPS) studies were carried out on the (0.30)Ag2O(0.70)[xB2O3 · (1 - x)TeO2] system. Tg was found to increase as the B2O3 progressively substitutes for the TeO2 content while the modifier content [Ag2O] was kept constant. The observed increase in Tg was correlated to the corresponding increase in oxygen packing density. The mixed former effect has been observed in these glasses. The maximum value of the conductivity σ ionic was found to be 2.82 × 10 6 S cm-1 at 100°C for the composition (0.30)Ag2O(0.28)B2O3(0.42)TeO2. The electronic contribution to the total conductivity of this particular glass sample was found to be 1.75 × 10 11 S cm 1. The non-bridging oxygen (NBO) atoms were distinguished from the bridging (BO) atoms from the deconvoluted O 1s XPS spectrum. The contribution to the NBO atoms has been attributed to the various oxygen species like Te=O, Teax-O , Teeq-O and B-O . The deconvoluted Gaussian peaks of the Te 3d XPS spectrum shows the presence of various possible structural units of tellurium atoms like TeO4, TeO- 3, TeO2- 3 and the Ag-Te bond.