ULTRAFINE OXIDE POWDERS PRODUCED BY RAPID THERMAL DECOMPOSITION OF PRECURSORS IN SOLUTION

ABSTRACT The Rapid Thermal Decomposition of precursors in Solution (RTDS) process is described as an approach to nanoscale particle production. The RTDS method involves a brief (< 2 sec) exposure of an aqueous solution containing dissolved metal oxide precursors to hydrothermal conditions amenable to particle nucleation and growth. Particle growth is terminated by passing the solution through a pressure restrictor and into a cooled collection region. Initial RTDS results involving the production of iron, titanium, and zirconium oxide powders from aqueous solutions are described. Powders generated were characterized using transmission electron microscopy, powder X-ray diffraction, BET surface area analysis, and Mossbauer spectroscopy. Iron oxide (hematite phase) having crystallite sizes ranging from a few nanometers to tens-of-nanometers was produced (rom 0.1 M Fe(NO3) 3 and Fe(NH4)(SO4) 2 solutions. Crystallite size in the hematite powders was found to be dependent on the temperature to which the solution...