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 above system has been determined. A comparative study of the direct current electrical conductivity, σ, of the 15Fe2O3–5Sb–80TeO2 (mol%) glass together with 15Fe2O3–5Sb2O3–80TeO2 and the binary 15Fe2O3–85TeO2 glass has been made in the temperature range 463–598 K. The 15Fe2O3–5Sb–80TeO2 glass was found to be most conductive (σ=1.39×10−5 S cm−1 at 503 K) in this series. The semiconducting behavior of these glasses could be explained by the small polaron hopping model. The oxygen gas-sensing property of the 15Fe2O3–5Sb–80TeO2 glass was investigated. The O2 gas sensitivity at 598 K was found to be 8.1. The variation in conductivity on alternate switching of gas atmospheres between oxygen and argon was found to be reproducible. An attempt has been made to clarify the mechanism of conductivity response considering the phenomenon of surface adsorption followed by bulk diffusion. From the investigation of the gas-sensing behavior, the present glass was found to be a potential candidate for an oxygen gas sensor.