Thermal Properties and Phase Transformation of 2mol% Y2O3-PSZ Nanopowders Prepared by a Co-precipitation Process

Two mol% Y2O3-PSZ precursor powders for dental applications were synthesized using ZrOCl2ADT8H2O and Y(NO3)3ADT6H2O by a co-precipitation process at pH 7 and 348K for 2h. The thermal properties and phase transformation of 2Y-PSZ nanocrystallite powder have been investigated using a thermogravimetric and difference scanning calorimeter (TG/DSC), Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy (TEM), selected area electron diffraction and dilatometric analysis. Two weaker broad exothermic peaks appear at around 618 and 718K were explored in DSC results. The TG analysis shows that minor weight loss occurs from 298 to 348K, followed by three major weight losses at 610, 630 and 773K. Calcinated at 773 and 1273K, the crystallized phases are composed of the major phase of tetragonal ZrO2 and minor phase of monoclinic ZrO2. TEM reveals that the tetragonal ZrO2 with an average size of less than 20.0nm is mainly aggregated into the secondary aggregates with a size of small than 30.0nm. The sintering curve of the compact pellet has a significant shrinkage with a linear rate of 18.5% at about 1341K. Maximum densification rate happened at 1473K, demonstrating the good low temperature sinterability for dental applications.