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.

On the Grain Boundary and Defect Structure of Nanocrystalline Titanium Oxide. Rickerby, D.G.: Philosophical Magazine B, 1997, 76[4], 573-83