Effects of seeding on the crystallisation kinetics of air-calcined yttria-doped hydrous zirconia

Yttria-doped tetragonal zirconia (Y-TZP, 3 mol% Y2O3) amorphous precursors seeded with nanometric ic Y-TZP particles (10 wt%) were prepared by the sol-precipitation method. Solid-state reactions occurring during heating were studied by differential thermal analysis and X-ray diffraction. It was found that the seeding of Y-TZP amorphous precursors with 10 wt% crystalline Y-TZP nanometric particles considerably lowered the onset of the Y-TZP solid solution crystallisation temperature by nucleation and epitaxial growth. Thus, a complete Y-TZP solid solution was formed in the temperature range of 320-350 degrees C in air after a heat-treatment of 20 h, by seeding the Y-TZP amorphous precursors with 10 wt% of Y-TZP nanometric crystalline particles. The isothermal crystallisation kinetics for an unseeded and 10 wt% Y-TZP nanometric particles seeded Y-TZP precursors have been compared. The seeded Y-TZP precursors exhibited enhanced crystallisation kinetics (about one order of magnitude higher), and the activation energy for the Y-TZP solid solution crystallisation was reasonably lowered (from 184 kJ mol(-1) to 119 kJ mol(-1)). (C) 1997 Elsevier Science Limited.