Crystallization behavior of tetragonal ZrO2 prepared in a silica bath

The synthesis of zirconia (ZrO2) precursor powders by a co-precipitation process is studied in this work, using a silica bath prepared at 348 K and pH = 7, with 10 min mixing using zirconium (IV) nitrate and tetraethylorthosilicate (TEOS, Si(OC2H5)4) as the starting materials. The XRD result show that only a single phase of tetragonal ZrO2 (t-ZrO2) appears when the freeze dried precursor powders are calcined between 1173 and 1473 K for 120 min. The activation energy of t-ZrO2 crystallization, as calculated by the Johnson–Mehl–Avrami (JMA) equation, is 643.0 ± 13.9 kJ/mol. The growth morphology parameter (n) and crystallization mechanism index (m) are approximated as 3.0, which indicates that bulk nucleation is dominant in the t-ZrO2 crystallization process, and that the material has a plate-like morphology.