Thin (111) oriented CoFe2O4 and Co3O4 films prepared by decomposition of layered cobaltates

Abstract

The formation and structural characterization of highly (111)-oriented Co3O4 and CoFe2O4 films prepared by a novel procedure from 00l-oriented NaCoO2 and Na(CoFe)O2 is reported. The Na(CoFe)O2 films were deposited on MgO, SrTiO3, LaAlO3, and Zr(Y)O2 single crystals with (100) and (111) orientations by chemical solution deposition method and crystallized at 700°C. Subsequently they were transformed into (111)-oriented spinel phase during post-growth annealing at 800–1000°C. Morphology and structure of the films was investigated by means of scanning electron microscopy and X-ray diffraction. While all spinel films exhibit pronounced out-of-plane orientation irrespective of substrate, the rate of in-plane orientation strongly depend on lattice misfit values. Different epitaxial phenomena ranging from true one-to-one epitaxy to the existence of many-to-one epitaxy involving two or more orientations were determined by full 3D texture analysis.