tsirkooniumoksiid ZrO2; esineb kolmel kristallilisel kujul : monokliinne (kuni 1170 oC), tetragonaalne (1170-2370 oC) ja kuubiline (üle 2370 oC), oxide of zirconium ZrO2; three crystalline structures are known: monoclinic below 1170 oC, tetragonal between 1170 oC and 2370 oC, and cubic above 2370 oC; widely available, naturally occuring ceramic material