Transmission electron microscopy was used to study the crystal size distribution, grain-boundary disorder and defect structure in nanocrystalline specimens which had been prepared by means of reactive sputtering. The average grain diameter, as determined by measurements of dark-field micrographs, was about 15nm. Evidence of both ordered and disordered grain-boundary regions was found, and planar defects which were observed within grain interiors were identified as being (011) deformation twins. The crystallographic shear defects, that could occur as a result of the aggregation of O vacancies in the hypo-stoichiometric oxide, were rarely present. No dislocations, apart from those required in order to accommodate misfit, were seen.

D.G.Rickerby: Philosophical Magazine B, 1997, 76[4], 573-83