Effect of Prefiring Condition on the In-Plane Orientation of Epitaxial Oxide Films in Coating-Pyrolysis Process

Epitaxial -Fe₂O₃ films were obtained by using iron 2-ethylhexanoate as a starting material. A coating solution was spun on -Al₂O₃ single-crystal substrates, and prefiring and final heat-treatment at various temperatures in air or low oxygen partial pressure were carried out. The degree of in-plane orientation was estimated in terms of full width at half maximum of X-ray diffraction (XRD) -scans. The results of TG-DTA, IR, and XRD suggested that the optimum prefiring condition for obtaining highly epitaxial films is in the range 200–300°C which corresponds to removal of most of the organic component from the precursor, prior to crystallite formation of metal oxide. When the films were prefired at higher temperatures, different atmospheres in prefiring and final heat-treatment lowered the in-plane orientation of the films.