Synthesis of nanosized ceramic oxide powders by microwave plasma reactions

Abstract This paper describes a novel process using a microwave plasma as a source of energy to synthesize ceramic oxide powders with mean particle size in the range of 5 to 30 nm. The process works without solvents by evaporation of chlorides of the elements used in ceramics. The process was demonstrated by the synthesis of alumina-, titania- and zirconia-based ceramic powders. Air or one of the noble gases mixed with any amount of oxygen and water was used as process gas. Electron microscopy revealed that through proper selection of synthesis conditions, it is possible to obtain nanocrystalline powders. Due to the extreme conditions during synthesis it is possible to prepare non-equilibrium phases or solid solutions in systems exhibiting no equilibrium solubility.