Metastable Retention of a High-Pressure Phase of Zirconia

A high‐pressure phase of zirconia, stable above 3.3 GPa at room temperature, can be retained metastably, at ambient room conditions of pressure and temperature by appropriate thermal/pressure treatments. The amount of high pressure phase retained depends on the thermal treatment, hydrostatic environment, and particle size of the starting powder. The results support the idea that the high‐pressure transformation in zirconia is initiated at nucleation centers whose population can be minimized by appropriate thermal treatments. The results also point out the importance of high pressure as a source of controllable driving force to induce the transformation in zirconia, thus permitting the use of annealing treatments to change the population of defects involved in nucleating the transition.