The morphologies of the as-received ZrO2 and the synthesized CaZrO3 powders from the reacted mass heated for 5 h at 1050°C are shown in Fig. 4. The shape of the CaZrO3 grains (rounded/angular) was similar to that of the ZrO2 powder, although their size (0.5–1.0 μm) was greater than the ZrO2 (0.2–0.5 μm).