DIRECT-CURRENT CONDUCTIVITY AND OXYGEN GAS-SENSING PROPERTIES OF IRON-ANTIMONY-TELLURITE GLASSES

Iron tellurite glasses in the system Fe2O3-Sb-TeO2 have been prepared by the melt-quenching technique. The glass forming region for the abov e system has been determined. A comparative study of the direct curren t electrical conductivity, sigma, of the 15Fe(2)O(3)-5Sb-80TeO(2) (mol %) glass together with 15Fe(2)O(3)-5Sb(2)O(3)-80TeO(2) and the binary 15Fe(2)O(3)-85TeO(2) glass has been made in the temperature range 463- 598 K. The 15Fe(2)O(3)-5Sb-80TeO(2) glass was found to be most conduct ive (sigma = 1.39 x 10(-5) S cm(-1) at 503 K) in this series. The semi conducting behavior of these glasses could be explained by the small p olaron hopping model. The oxygen gas-sensing property of the 15Fe(2)O( 3)-5Sb-80TeO(2) glass was investigated. The O-2 gas sensitivity at 598 K was found to be 8.1. The variation in conductivity on alternate swi tching of gas atmospheres between oxygen and argon was found to be rep roducible. An attempt has been made to clarify the mechanism of conduc tivity response considering the phenomenon of surface adsorption follo wed by bulk diffusion. From the investigation of the gas-sensing behav ior, the present glass was found to be a potential candidate for an ox ygen gas sensor. (C) 1997 American Institute of Physics.