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.