Preparation and properties of gamma Fe2O3 and Y2O3 doped gamma-Fe2O3 by a sol-gel process

Ultra-fine gamma-Fe2O3 powders with average particle size of 10 nm were pre pared by a complexing sol-gel process. Thermal analysis, X-ray diffraction and FT-IR were employed to study the microstructure and thermal stability. The as-prepared gamma-Fe2O3 has high response to reducing gases. gamma-Fe2O 3 doped with Y2O3 to form a solid solution can raise its phase transition t emperature to as high as 775 degrees C and improve the resistance stability of the sensors without great change of their response and selectivity. The lifetime problem of gas sensors based on gamma-Fe2O3 is expected to be bas ically solved by doping method. (C) 1999 Elsevier Science S.A. All rights r eserved.