Quantitative Analysis of Phase Compositions of MgO-, CaO- or Y_2O_3-doped ZrO_2

ZrO2 powder doped with 8mol% MgO, CaO or Y2O3 was prepared by co-precipitation technique. The densified and partially or fully stabilized ZrO2 ceramics were obtained by sintering the powder under 1550℃. The quantitative analyscs of phase compositions of ZrO2 ceramics were performed based on X-ray profile diffraction data and Rietveld inethod. The results show that ZrO2 ceramics stabilized by MgO, CaO or Y2O3 with the same starting composition possess the different phase contents. MgO partially stabilized ZrOz consists of cubic, tetragonal and monoclinic phases with the weight ratio of 17:57:26, CaO partially stabilized ZrO2 contains cubic and monoclinic phases with the weight ratio of 68:32, Y2O3-doped ZrO2 shows almost a pure cubic phase with only 3 wt% tetragonal one, however. In the paper, the influence of grain size on phase transformation of tetragonal to monoclinic of ZrO2 is also discussed.