Synthesis of ultrafine single-component oxide particles by the spray-ICP technique

Abstract

Ultrafine oxide particles were synthesized by introducing aqueous solutions of metal salts into a high-temperature r.f. inductively coupled plasma (the spray-ICP technique). The particles synthesized were spherical for ZrO2, Y2O3, Sm2O3, La2O3, δ-Al2O3, TiO2 (anatase), β-Bi2O3 and CuO, plate-like for Nd3O2, Cr2O3 and Pr2O3, polyhedral for PrO2, CeO2 and γ-Fe2O3, cubical for NiO, MgO, CaO, Co3O4 and Mn3O4, bar-like for SnO2 and ZnO, and foil-like for β-PbO and MoO3. The products of the alkaline earth group except for magnesium, were hydroxides and/or carbonates, spoiled by atmospheric H2O and/or CO2. The particle morphology suggests that particle growth is controlled predominantly by the gas-solid reaction occurring on the surface of nuclei condensed from the gas phase. Some of the oxides revealed a particle morphology characteristic of their crystal structures.