Effect of MgO segregation and solubilization on the morphology of ZrO2 powders during synthesis by the Pechini's method

Studies carried out in several ceramic oxide systems have shown that segregation of ions during synthesis of ceramic materials by the Pechini's method has important morphology consequences for the powder. The aim of this paper is to establish the influence of the MgO segregation/solubilization on the morphology of ZrO2 powders. The study was performed in powders prepared by chemical synthesis derived from the Pechini's method at 500 ºC for 15 h. It is observed that MgO concentrations up to the solubility limit promote ZrO2 particle coarsening and a reduction of specific surface area by increasing the diffusion coefficient. However, MgO amounts higher than the solubility limit increase the specific surface area due to the segregation of Mg ions onto powder surfaces, and the decrease of surface energy. MgO concentrations as high as 60 mol % were used and specific surface areas about 120 m²/g were achieved. However, only zirconia solid solution crystalline phase was observed, without MgO crystalline phases.

zirconia; Pechini; segregation; surface energy; sintering