Preparation and Formation Process of Various Iron Oxide Films by Thermal Decomposition of Iron Naphthenate

Abstract

The iron naphthenate coated on a glass substrate thermally decomposed to Fe3O4, γ-Fe2O3 and α-Fe2O3 films by the calcination at a temperature range from 200 to 800°C. These iron oxide films were examined by X-ray diffractometry, colorimetric analysis and electron microscopy.The details of the change of iron oxides prepared on the films were as follows:1) The solid solution of Fe3O4-γ-Fe2O3 system crystallized at the temperature range from 250 to 400°C. The lattice constant of the solid solution continuously decreased and the degree of oxidation increased as the calcination temperature rose up to 400°C.2) The pure γ-Fe2O3(a0=8.338Å) crystallized at the temperature range from 450 to 500°C for 4h. This γ-Fe2O3 was stable on calcining over long time at this temperature range.3) The γ-Fe2O3 transformed to α-Fe2O3 above 500°C with the increase in the grain size. The amount of α-Fe2O3 increased with a rise in the calcination temperature and time.4) The color of the film obtained below 500°C was yellowish brown. The color changed to brownish red above 550°C, because the γ-Fe2O3 transformed to α-Fe2O3.5) The thickness of the film prepared above 400°C ranged between 2000-2500Å.