Crystalline transformation of Ti-B-O, Al-Ti-B-O, Si-Ti-B-O and Al-Si-Ti-B-O by thermal treatments

Abstract

The thermal transformations of Ti-B-O, Al-Ti-B-O, Si-Ti-B-O and Al-Si-Ti-B-O have been investigated using the methods of thermal analysis and X-ray powder diffraction. The materials are a crystalline series of TiO2 with partial replacement of titanium by the elements, aluminium, boron and silicon. The anatase form of the materials was transformed to the rutile form at 520∼680 °C for Ti-B-O, 880∼950 °C for Al-Ti-B-O, 1080∼1280 °C for Si-Ti-B-O and 1180∼1330 °C for Al-Si-Ti-B-O. The rate constant for the anatase-rutile transformation of Ti-B-O was 6.908×10-3 min-1 under isothermal conditions at 680 °C. Analysis of the kinetic data obtained by differential thermal analysis (DTA) gave the activation energy for transformation of anatase into rutile as 663.7 Kcal mol-1 for Al-Ti-B-O. The lattice parameters for the compounds studied at various temperatures were calculated by least-squares fitting of the X-ray powder diffraction data. © 1993 Chapman & Hall.