Partially Stabilized Zirconia

Zirconium oxide exists in monoclinic crystal at room temperature, and will be converted into square crystal phase as temperature rises to 1,170°C and then converted into cubic crystal phase as temperature rises to 2,370°C, while cubic crystal phase will be dissolved into liquid phase at 2,680°C, the conversion from square crystal into monoclinic crystal is a martensitic transformation, and such phase conversion may produce 3 – 5% volume change, resulting micro cracks. 

Effective dopants include Yttrium oxide (Y₂O₃), Magnesium oxide (MgO),  Calcium oxide (CaO) which stabilizing agents to make sure that zirconium oxide can maintain the high-temperature stable phase, that is cubic crystal phase, which is called the stabilized zirconium oxide; if yttrium oxide phase stabilizer is added to keep partial square crystal phase, it can be called partially stabilized zirconium oxide.