EFFECTS OF Y-DOPING ON THE FORMATION, STRUCTURE AND PROPERTIES OF IRON-OXIDE

The effects of Y-doping on the phase formation in an FeSO4-Na2CO3 susp ension system were determined. The phase, microstructure and thermal s tability of the samples were studied by XRD, TEM and TG-DTA. It was fo und that Y appears to restrain the nucleation and growth of alpha-FeOO H, but facilitates the formation of gamma-FeOOH. Partly doe to Y-dopin g, tetragonal gamma-Fe2O3 from direct dehydration of gamma-FeOOH has h igh thermal stability, and the phase transition temperature of gamma-F e2O3 --> a.Fe2O3 is increased to 725 degrees C. The properties of cubi c gamma-Fe2O3 obtained from Y-doped alpha-FeOOH were also investigated .