OPTICAL, INFRARED AND ELECTRICAL-CONDUCTIVITY OF GLASSES IN THE TEO2B2O3 SYSTEM

Infrared (IR) and optical absorption spectra were measured in order to study the structure of some tellurite glasses containing boric oxide. The compositions (mol%) were (100-X) TeO2, XB(2)O(3) where X = 5, 10, 20, 25, 30. The optical spectra were measured at room temperature in the wavelength range 350-450 nm, and the results show that the fundame ntal absorption edge is a function of composition, with the optical ab sorption due to indirect transitions. The optical band gap increases w ith increasing B2O3 content. The validity of the Urbach rule was inves tigated. The IR results prove the distribution of the TeO4 polyhedra w hich determines the network and the basic oscillations of the building units in the tellurite glasses. The IR results also prove the distrib ution of the boroxal group. The electrical conductivity was measured a s a function of temperature in the temperature range (300-573 K). Both the conductivity and activation energy were found to be a function of added oxide type.