Preparation and characterization of nano-scale Y2O3-ZrO2 powder by heterogeneous precipitation

Calcined pure zirconia (main monoclinic) particles were coated with yttria by heterogeneous precipitation method, and 3 mol% Y2O3-ZrO2 nano-scale powder was prepared. During the preparation procedure, Y2O3 was initially enriched outside and around the ZrO2 particles. Auger electron spectroscopy (AES) of the powder surface showed that there was signal with the relative intensity due to Y element after the heterogeneous precipitation. Y2O3 on the surface of the pure ZrO2 particles intermingled into the crystal lattice of ZrO2 gradually and influenced the structure of ZrO2 during the calcination. Depending on the calcination temperature, the structure of zirconia changed from mixed monoclinic-tetragonal to tetragonal. TEM micrographs indicated that the as-prepared 3 mol% Y2O3-ZrO2 powder was not larger than 50 nm even calcined at 900degreesC. BET surface areas of the powder increased obviously after the coating attributed to the elimination of the aggregation of ZrO2.