Is it “cubit” or “cubic” zirconium?
Neither. It’s “cubic zirconia”. Zirconium is a metallic element. Zirconia is the compound ZrO2, also called zirconium dioxide. ZrO2 can exists in monoclinic, tetragonal, or cubic crystal structures. The monoclinic form is the thermodynamically stable form of pure ZrO2 at temperatures up to ~1200C. Above that temperature, the tetragonal structure is stable. The cubic structure is produced by adding small quantities of another oxide (e.g., MgO or a rare-earth oxide) to the zirconia. This lowers the energy of the cubic structure relative to the tetragonal structure (at high temperature), and if such a sample is “quenched” from high temperature to room temperature, the cubic structure is “frozen in”, even though it is not stable relative to the monoclinic structure.
