SYNTHESIS OF YTTRIA POWDERS BY ELECTROSPRAY PYROLYSIS

Electrospray atomization of high-concentration (similar to 400 g/L) chemical precursor solutions was applied to the synthesis of yttria powders, Conditions mere found which led to high-quality powders, composed of dense, spheroidal, submicrometer, and nanocrystalline oxide particles, The precursor solutions were hydrated yttrium nitrates dissolved in n-propyl alcohol at concentrations ranging from 44.1 to 455 g/L. Electrospray atomization produced submicrometer precursor droplets which were dispersed in air and carried through an electric furnace for thermal decomposition at 500 degrees C for several seconds residence time, X-ray powder diffraction patterns indicated the expected cubic phase, Transmission electron micrographs showed that the particle structure varied with solution composition, ranging from hollow, inflated spheres for 6-hydrated nitrates to dense spheroids for 5-hydrated nitrates, The use of 6-hydrated nitrates in the solutions appeared to form particle surfaces which mere impermeable to alcohol vapor evolved during thermal decomposition, leading to hollow, inflated spheres.