ZrO₂-Y₂O₃セラミックス系に出現する正方晶

抄録

The phase stability of the cubic and tetragonal phase in ZrO₂-2-6mol% Y₂O₃ is studied by X-ray diffraction method and transmission electron microscopy. Two kinds of tetragonal phase, t and t', and a cubic (t'') phase, are identified consistently. The t-phase is the equilibrium tetragonal phase, which transforms martensitically to the monoclinic phase on further cooling. The t'-phase has a thin plate or lamellar structure, and is formed in the decomposed structure of the cubic (t'') phase. The high resolution electron microscopy reveals that the fine domains (t''-phase) due to displacement of oxygen atoms appear dispersedly in the initial stage of decomposition, resulting in the tweed contrast.