Synthesis and characterization of spherical calcia stabilized zirconia nano-powders obtained by spray pyrolysis

Fine, spherical Ca0.15Zr0.85O1.85 nano-powders were prepared by spray pyrolysis, starting from a mixed aqueous and ethylic solution of zirconium acetylacetonate and calcium acetate. The influence of solution concentration, furnace temperature, mass flow of carrier gas and voltage of precipitator on microstructure, average particles size and recovery percentage were evaluated. The powders were synthesized without sintering, and for adequate preparation conditions, were mostly spherical, solid and narrowly size distributed. Average particle size ranges between 40 and 350 nm. Transmission electron micrographs showed that crystalline calcia stabilized zirconia particles were constituted by small crystallites, their size varying between 2 and 40 nm. X-ray diffraction analysis shows that powders obtained at low temperature were amorphous; for higher temperatures (∼800 °C), it is found the presence of the tetragonal and cubic phases.