Phase evolution, microstructure, and gas-sensing characteristics of the Sb2O3-Fe2O3 system prepared by coprecipitation

Precursor powders with antimony-to-iron (Sb/Fe) atomic ratios ranging from 0 to 2.0 were prepared by chemical coprecipitation. The origin of enhanced gas-sensing behavior at a higher calcining temperature was investigated, ba sed on phase evolution and microstructure characterized by means of thermal analysis, x-ray diffraction, Brunauer-Emmett-Teller surface area measureme nt, and electron microscopy. Only one iron-antimony oxide (i.e., FeSbO4) co uld be obtained under present experimental conditions. Pure FeSbO4 exhibite d a high gas sensitivity, only when calcining temperature was below 600 deg reesC. A rapid crystallite growth, as well as hard agglomeration, occurred in pure FeSbO4 powder calcined at 600-1000 degreesC, and thus led to poor g as-sensing behavior. However, there existed an optimal Sb/Fe ratio range (i .e., 0.25 to 0.65) in which crystallite growth of both alpha -Fe2O3 and FeS bO4 could be efficiently depressed up to 800 degreesC. The samples (with Sb /Fe ratio in the range 0.25-0.65) calcined at 600-800 degreesC displayed a high sensitivity to liquid petroleum gas due to their large specific surfac e area and poor crystallinity.