EFFECT OF SIO2, NACL, AL2O3, AND FECL3 ON PHASE-CHANGE BEHAVIOR OF SUPPORTED AND UNSUPPORTED TIO2

The anatase-rutile phase change temperatures in TiO2 powders precipitated from aqueous TiCl4 and the same deposited on muscovite and phlogopite micas were investigated. Doping with Al2O3, NaCl, and SiO2 increased the phase change temperature of supported and unsupported TiO2, but doping with FeCl3 · 6H2O decreased the beginning temperature of the phase change on unsupported TiO2. The difference in phase change dependence on temperature between undoped TiO2 supported by micas and unsupported TiO2 was caused by diffusion of aluminum, silicon, and sodium ions from the mica substrate during the calcination step. © 1993 Academic Press. All rights reserved.