Influence of Sb/Fe ratio and heating temperature on microstructure and gas-sensing property of Sb2O3Fe2O3 complex oxide semiconductors

The preparation, characterization and gas-sensing properties of the Sb 2 O 3 Fe 2 O 3 complex oxide system have been investigated. Raw powders (with Sb/Fe = 0.2–1.0) of this system have been obtained by chemical coprecipitation. Effects of the Sb/Fe ratio and calcining temperature on the phase constituents and microstructure are characterized by thermal gravimetric-differential thermal analysis, X-ray diffraction and transmission electron microscopy. In the Sb 2 O 3 Fe 2 O 3 system, Fe 2 Sb 2 O 7 can be used as a new type of gas-sensing material, which has a fair sensitivity to reducing gases. However, of all the samples the powder with Sb/Fe = 0.5 calcined below 800°C, composed of 50% α-Fe 2 O 3 and 50% Fe 2 Sb 2 O 7 , exhibits the highest sensitivity to some hydrocarbon gases such as C 2 H 2 , petrol and liquid petroleum gas (LPG). This is attributed to both very fine crystallites and the amorphous phase of α-Fe 2 O 3 existing in the sample.