Mobility size development and the crystallization path during aerosol decomposition synthesis of TiO2 particles

Size and morphology transformation as well as the crystallization path of m onodisperse titanium dioxide particles were studied in aerosol flow reactor . Solid, hydrated titanium oxide particles were prepared from titanium alko xide by a droplet hydrolysis acid a subsequent size classification. The par ticles were carried to a reactor in air at temperature range of 20-1500 deg reesC. The inlet particle size of 100 and 200 nm gradually decreased 40% wi th increasing temperature as investigated by a tandem differential mobility analyzer (TDMA) system. The decrease was due to decomposition of the hydra ted Ti-O particles. densification of the forming TiO2 particles, and a phas e change from anatase to rutile. Above 1000 degreesC the mobility size incr eased due to crystal-habit formation that created faceted, elongated partic les and consequently an increased dynamic shape factor. Microstructure inve stigations with a transmission electron microscope (TEM) showed that nanocr ystalline anatase particles were present at 600 degreesC and transformed to rutile up to 1100 degreesC with simultaneous crystallite growth. Single-cr ystal rutile particles were observed at temperatures with the increased mob ility diameters. (C) 2001 Elsevier Science Ltd. All rights reserved.