Growth habit of rutile and α-Al2O3 crystals

The growth habits of TiO2 and alpha-Al2O3 crystals are observed on the synthetic crystals in the hydrothermal or glycothermal solutions by means of TEM and ED analysis. It is concluded that the habit of alpha-Al2O3 crystal should be the hexagonal platy {0 0 0 1} with the {1 1 (2) over bar 3} faces; the growth habit of rutile is an elongated prism, bounded by {1 1 0}, {1 0 0} and {1 0 1} forms. These results are successfully explained by a new rule concerning growth habit proposed by Wen-Jun Li et al. (J. Crystal Growth, 1999, to be published). Moreover, the growth habit of rutile is related to the concentration of precursor (TiCl4 solution). When the concentration of TiCl4 solution increases from 0.25 to 1 mol/l, the morphology of particles is changed from prismatic form to elongated prismatic form. Its habit change is analyzed through the study of the growth mechanism of rutile. (C) 2000 Elsevier Science B.V. All rights reserved.