Pase decomposition in zirconia ceramics

研究了ZrO_2-CeO_2和ZrO_2-R_2O_3 （R：稀土）体系的立方-四方（c-t）两相平衡及其相关现象。所得结果总结如下：(1)近化学计量ZrO_2-CeO_2的c-t相变被认为是一个二级相变。(2)在非化学计量（Zr, Ce） O_2-x中，-氧离子以立方形式有规律地向<111>方向移位。由于立方萤石结构的位移，在衍射图中出现了多种禁反射。(3)非化学计量（Zr, Ce） O_2-x中的c-t相变具有一级相变性质。(4) ZrO_2-R_2O_3体系中的c-t两相场与R^<3+>离子的类型有关。在c-t变换为二阶型的假设下，热力学评价成功地描述了各种ZrO_2-R_2O_3体系中观察到的两相场。(5)采用机械合金制备ZrO_2-ZrN固溶体是可能的；

The cubic-tetragonal (c-t) two-phase equilibria in ZrO_2-CeO_2 and ZrO_2-R_2O_3 (R : rare earths) systems and related phenomena were examined. The results obtained are summarized as follows.(1) The c-t transformation in near-stoichiometric ZrO_2-CeO_2 is regarded as a second-order phase transition.(2) In nonstoichiometric (Zr, Ce) O_2-x, -oxygen ions are regularly displaced in the <111> direction in a cubic form. A variety of forbidden reflections appear in the diffraction patterns by the displacement in cubic fluorite structure.(3) The c-t transformation in nonstoichiometric (Zr, Ce) O_2-x has a nature of first-order phase transition.(4) The c-t two-phase field in ZrO_2-R_2O_3 systems is dependent on the type of R^<3+> ions. Thermodynamic assessment is successful to describe the observed two-phase fields in vaious ZrO_2-R_2O_3 systems on the assumption that the c-t transformation is of a second-order type.(5) It is possible to obtain ZrO_2-ZrN solid solutions by mechanical alloyins,