Nanocrystalline zirconia based powders synthesized by hydrothermal method

Nanocrystalline powders in the ZrO 2 -Y 2 O 3 -CeO 2 -CoO-Al 2 O 3 system with 1 and 10 mol% Al 2 O 3 were prepared via hydrothermal treatment in alkaline medium. The characteristics of nanocrystalline powders after heat treatment in the temperature range from 500 to 1200 °C were investigated by XRD phase analysis, scanning electron microscopy, petrography and BET measurements. It was found that hydrothermally treated powders contained metastable low-temperature cubic solid solution based on ZrO 2 and addition of Al 2 O 3 increased temperature of phase transformation of the metastable cubic- ZrO 2 to tetragonal-ZrO 2 . It was evidenced that both powders remained nanocrystalline after all processing steps with the average particle sizes from 8 to 20 nm. The addition of 0.3 mol% CoO allows one to obtain composites with good sinterability at 1200 °C