Extended versus small defect-equilibria in non-stoichiometric rutile. I. Dissolution and re-precipitation of extended defects observed by in-situ transmission electron microscopy

Extended defects accomodating non-stoichiometry in rutiles reduced slightly to compositions of TiO1.9966, TiO1.9979, and TiO1.9986 are seen to dissolve in situ in an electron microscope using a goniometer at temperatures of up to 1000 °C. This allows to determine as directly as possible the stoichiometry dependence of the dissolution temperature, and hence the phase limits of nonstoichiometric TiO2−x. The defect structures formed during dissolution, and also the reprecipitation of extended defects upon cooling of the specimens to room temperature, are also studied.