Morphology and microstructural properties of TiO₂ nanopowders doped with trivalent Al and Ga cations

The effects of doping on the morphological and microstructural properties of TiO₂ nanopowders produced by laser pyrolysis were investigated mainly by x-ray diffraction (XRD) and electron microscopy. Samples of TiO₂ powders were prepared by doping with different trivalent cations (Al and Ga). The powders were calcined at different temperatures in the range 400–1000 °C for 18 h, as well as at constant T = 700 °C up to 160 h. After each thermal treatment, XRD patterns were collected. The analysis of XRD patterns allowed us to estimate the microstrains and average crystallite size and to observe the evolution of the microstructural parameters with temperature. Both Al and Ga inhibited the crystallite growth of TiO₂ anatase and the rutile phases, this effect being larger in the Al-doped powders.