SYNTHESIS AND CHARACTERIZATION OF SILVER BOROTELLURITE GLASSES

The glass transition temperature, T-g; density, rho; ionic conductivit y, sigma(i) and X-ray photoelectron spectroscopy (XPS) studies were ca rried out on the (0.30)Ag2O(0.70)[xB(2)O(3) . (1-x)TeO2] system. T-g w as found to increase as the B2O3 progressively substitutes for the TeO 2 content while the modifier content [Ag2O] was kept constant. The obs erved increase in T-g was correlated to the corresponding increase in oxygen packing density. The mixed former effect has been observed in t hese glasses. The maximum value of the conductivity sigma ionic was fo und to be 2.82 x 10(-6) S cm(-1) at 100 degrees C for the composition (0.30)Ag2O(0.28)B2O3(0.42)TeO2. The electronic contribution to the tot al conductivity of this particular glass sample was found to be 1.75 X 10(-11) S cm(-1). The non-bridging oxygen (NBO) atoms were distinguis hed from the bridging (BO) atoms from the deconvoluted O 1s XPS spectr um. The contribution to the NBO atoms has been attributed to the vario us oxygen species like Te=O, Te-ax-O-, Te-eq-O- and B-O-. The deconvol uted Gaussian peaks of the Te 3d XPS spectrum shows the presence of va rious possible structural units of tellurium atoms like TeO4, TeO3-, T eO32- and the Ag-Te bond.