Direct Laser Synthesis of Fe2O3 modified TiO2

Abstract

A very fast, selective CO2 laser line scan direct synthesis method is presented and has been applied here to study phase and defect formation within an irradiated mixture of powdered oxides, as a proof‐of‐principle. A nominal composition interval of 0<x<0.03 was conveniently chosen for the TiO2+xFe2O3 system herein reported. X‐ray diffraction analyses were used to determine the main crystalline phase composition. Thus, for 3% mol. Fe2O3, pseudobrookite crystals were found to coexist with rutile‐type MO2‐δ (M=Ti, Fe) with extended defects. These are composed mainly of (121)r and (132)r crystallographic shear planes (CSP`s), where the r sub‐index refers to the rutile subcell. For samples with a lower Fe2O3 content (2, 1, 0.5% mol) only iron‐doped rutile phases were observed, with complex microstructure arising from the presence of multi‐twinned (011)r and (110)r crystals and isolated and/or ordered CSP`s at short length scale. The diverse microstructures observed in the CO2 laser produced samples correlate with the conditions imposed during the laser treatment, which include intrinsically high solidification rates and steep temperature gradients.