Processing of iron-doped titania powders in flame aerosol reactors

A flame aerosol reactor was used to synthesize Fe(III)-doped titania powder s. The processing conditions were controlled to obtain varying ratios of Fe :Ti in the as processed powders. The iron was incorporated into the titania lattice and promoted the conversion of the anatase to the rutile phase. Wi th an increase in the iron dopant concentration, a decrease in the crystal size of the resultant titania particles was observed, along with a conversi on to the amorphous state. The defect structure was further explored by Ram an spectroscopy, revealing an increased shift and broadening of the anatase peaks with an increasing iron dopant concentration, and was attributed to shrinkage in the grain size. Absorption spectra revealed a shift of the abs orption band toward the visible frequencies. Powders with Fe:Ti ratio excee ding 0.8 resulted in a binary mixture that had superparamagnetic characteri stics. (C) 2001 Elsevier Science S.A. All rights reserved.