High-resolution electron micrographs were presented of a specimen of TiO1.9966, which had been heated at 750C in an electron microscope, in order to dissolve extended defects. This revealed the size and distribution of the small (⪅ 1nm diameter) defects produced following dissolution of crystallographic shear planes, and also during cooling of the specimen to room temperature. The observed dissolution and re-precipitation phenomena were explained in terms of new models for the small defects, traditionally cation interstitial and/or oxygen vacancy defects, responsible for the non-stoichiometric phase TiO2-x. Asymmetry between precipitation and dissolution mechanisms was expected to lead to temperature hysteresis.

Extended versus Small Defect Equilibria in Non-Stoichiometric Rutile. II. Structural Mechanisms for Dissolution and Reprecipitation of Extended Defects. Blanchin, M.G., Bursill, L.A.: Physica Status Solidi A, 1984, 86[2], 491-8

Table 16

Diffusion of O vacancies in reduced rutile