Effects of Sulfate Ion on Gas Sensitive Properties of α-Fe₂O₃ Ceramics

Abstract

Alpha hematite (α-Fe 2 O 3 ) has been considered to have only a poor sensitivity to reducing gases. However remarkable gas sensitive properties were observed in the α-Fe 2 O 3 prepared from iron salts containing sulfate ion (SO 4 - ) by hydrolysis and precipitation. The sulfate ion remains in the α-Fe 2 O 3 but vaporizes at near 760°C. The vaporization causes crystallization of the α-Fe 2 O 3 and consequently results in a decrease in gas sensitivity. The sulfate ion is an extremely important factor in controlling the microstructure and plays a significant role in the gas sensitive properties of the α-Fe 2 O 3 ceramics.