Electrical conduction of composites of tin oxide and zinc oxide in hydrogen

A composite of tin oxide and zinc oxide was examined for possible application as a hydrogen gas sensor. The conduction mechanism of the composite was investigated in an atmosphere of hydrogen and air. For the composite, the temperature dependence of electric resistance suggests that the conduction mechanism in air differs from that in hydrogen. The electrical conduction in hydrogen was predominated by the hopping between tin dioxide grains and that in air was predominated by the conduction at the zinc oxide grain interface. The sensitivity of the composite to hydrogen gas was maximum at 460 K. The mechanical property of the specimen estimated from fracture strength was improved by adding zinc oxide to the composite.