Defect microstructures of TiO2 rutile due to Zr4+ dissolution and expulsion

Defect microstructure of Zr-dissolved TiO2 polycrystals, homogenized as rutile structure at 1600 °C and then aged at 900 °C for 2–200 h in air, was characterized by analytical electron microscopy. Diffuse diffractions occurred at 1/2(211) as a result of Zr4+ substitution for Ti4+ with volume/charge compensating defect clusters. Upon annealing at 900 °C, plate-like Guinier and Preston (G.P.) zone appeared with the plate surface parallel to (100) and (010) and in association with dislocations. Commensurate superstructures with apparent triple {101} and {111} periodicity also occurred as metastable intermediates, which are presumably the precursor of the equilibrium ZrTi2O6 precipitate.