水静压作用下氧化锆结构稳定性的第一性原理研究

First-principles Study of the Structural Stability of Zirconia under Hydrostatic Pressure

采用第一性原理计算了立方氧化锆（ZrO2）总的自由能、态密度、晶格常数随不同水静压的变化。计算表明单位晶胞总能量和晶格常数随水静压的增大而增大，晶格常数随水静压的增大而减小。在2．0GPa左右，单位晶胞总能和晶格常数随水静压的变化出现反常。对总态密度和Zr与O原子的分态密度分析表明，在低的水静压（0-5GPa）作用时，Zr与O原子的各轨道的布居数没有发生变化，水静压力的作用主要体现在各轨道之间的分布变化，单位晶胞总能量和晶格常数出现的反常对应于Zr原子p轨道中的态密度分布变化。当水静压超过5CPa时（5—30CPa），Zr原子中的s和p轨道占有数减少，d轨道占有数增多。

The total energy, density of states and lattice constant as functions of hydrostatic pressure for cubic ziroonia were calculated by a first - principles method. The calculated results show that the total energy of one unit increased with increasing of hydrostatic pressure, while the lattice constant decreased. The evolution of total energy of one unit and lattice constant has an anomaly when the external hydrostatic pressure is around 2.0 GPa. It is found that the total atomic populations of Zr and O has no change in the area of low hydrostatic pressure （0 -5 GPa）, only the distribution of each orbit itself has small change. The anomaly of total energy of one unit and lattice constant is related to the variation of p orbit of Zr under the small hydrostatic pressure. When the extemal hydrostatic exceeded 5 GPa, the total atomic populations of s and p orbits decreased, while the total atomic populations of and d orbits increased.