The structure and defects of thin epitaxial Cr2O3(00•1) overlayers on Cr(110) films were investigated by means of grazing-incidence X-ray diffraction. The Cr(110) films were prepared via molecular beam epitaxy before exposure to a controlled O atmosphere at temperatures ranging from 400 to 800K. Experimental results for the entire temperature range revealed the same in-plane orientational relationship between Cr2O3(00•1) and Cr(110). This was a Nishiyama-Wassermann type alignment between the O sub-lattice and the Cr(110) surface. Out-of-plane measurements demonstrated the presence of growth and deformation faults within the Cr-ion and O-ion sub-lattices. At higher temperatures, mainly twin formation occurred whereas, at lower temperatures, random stacking of the Cr-ion layers predominated. It was suggested that the twin grain boundaries served as diffusion channels for Cr ions during oxidation.

Structure and Defects of Epitaxial Cr2O3(0001) Overlayers on Cr(110). A.Stierle, T.Koll, H.Zabel: Physical Review B, 1998, 58[8], 5062-9