Semiconducting iron-tellurite and iron-aluminium-tellurite glasses were prepared by a press-quenching technique of the melt, and the helium gas-sensing behaviour of these was investigated. The glasses were n-type semiconductors. For powder-sintered pellet glass samples, the d.c. conductivity was larger in helium than in air and oxygen for the temperature range 463-598 K, and the conduction was confirmed to be due to small polaron hopping of electrons. In periodic switching of helium and air at 598 K, dynamic changes in conductivity were observed for both glasses, and the variations in conductivity were found to be reproducible. A helium gas sensitivity of 10.6 and 9.3 was obtained for both glasses, respectively. The dynamic changes in conductivity could be explained by a helium diffusion model. (C) 2001 Kluwer Academic Publishers. [References: 22]
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