Zirconia

Zirconia, or zirconium dioxide (ZrO2), is a white ceramic material valued for its combination of hardness, wear resistance, and toughness. Although zirconia occurs in nature only as trace minerals, commercial zirconia is produced as a polycrystalline ceramic. It is most often stabilized in the tetragonal or cubic phase at room temperature by dopants such as yttria (Y2O3), producing what is known as yttria-stabilized zirconia (YSZ).

Zirconia undergoes phase transformations with temperature. Pure ZrO2 is monoclinic at room temperature and transforms to tetragonal and then cubic phases with heating. Stabilizers suppress these transformations at ambient conditions, enabling a tougher material through transformation toughening when stressed.

Properties include high hardness and strength, good fracture toughness for a ceramic, strong wear resistance, low thermal conductivity, and chemical inertness. Biocompatibility is well established, contributing to many medical and dental uses. The microstructure and stabilizer content strongly influence performance.

Applications span dental restorations (crowns, bridges, and implants), orthopedic and other medical components, and engineering ceramics in aerospace, automotive, and industrial tooling. Zirconia is also widely used as a ceramic barrier coating in gas turbines and as a solid electrolyte or sensor material in energy devices.

Note: zirconia refers to ZrO2 as a ceramic; it should not be confused with cubic zirconia (CZ), a synthetic gemstone that mimics diamond.