Study of crystallization behavior and kinetics of ZrO 2 -3Y 2 O 3 - x SrO (1≤ x ≤3) precursor powders using an isothermal process

Abstract Zirconium nitrate (Zr(NO3)4·xH2O), yttrium nitrate (Y(NO3)3·6H2O) and strontium nitrate (Sr(NO3)2) were used as the starting materials for synthesized ZrO2-3Y2O3-xSrO (1≤x≤3) precursor powders. The isothermal crystallization behavior and kinetics were investigated using an isothermal process. The characterization used X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), nano-beam electron diffraction (NBED) and high-resolution TEM (HRTEM). The XRD results show that all patterns only contain the single phase of tetragonal ZrO2 (t-ZrO2) for ZrO2-3Y2O3-xSrO precursor powders after calcination between 773 and 923 K for various durations. When the ZrO2-3Y2O3-1SrO precursor powders were calcined at 923 K, the crystallinity of t-ZrO2 increased from 29.98% to 81.64% with rose calcined time from 15 min to 120 min. When calcination time was held at 60 min, the crystallinity of t-ZrO2 increased from 52.49% to 73.41% of ZrO2-3Y2O3-1SrO precursor powders with increasing calcination temperature from 773 K to 923 K. Moreover, when the precursor powders were maintained at the same calcination temperature and duration, the crystallinity of t-ZrO2 decreased with increasing addition of SrO. The activation energy and kinetics formula for t-ZrO2 crystallization of ZrO2-3Y2O3-xSrO precursor powders by an isothermal method were obtained.