二氧化铈固体的力学和热物理性质研究

Theoretical Study on Mechanical and Thermophysical Properties for Solid Cerium Oxide

采用基于第一性原理的赝势平面波方法系统地计算了二氧化铈固体基态的晶格结构,体积模量和弹性系数。与实验数据比较表明,Wu-Cohen广义密度梯度近似理论预测出的晶格常数比局部密度近似和Perdew-Wang广义密度梯度近似的更为准确。我们利用Wu-Cohen近似计算出的结构参数和力学常数,确定了Debye温度,并采用IDebye模型预测了二氧化铈固体的热膨胀系数和等压热容。与实验数据比较表明,理论预测出的热膨胀系数和热容与实验数据吻合得较好。

Structural parameter, bulk modulus and elastic constants of solid cerium oxide were calculated using the first-principles pseudopotential total energy method. The comparisons of calculated results with corresponding experimental data show that the lattice constant from the generalized gradient approximation （GGA） of Wu and Cohen is better than that from the local density approximation or Perdew-Wang generalized-gradient approximation. The Debye temperature was determined using the structural parameters and elastic constants from Wu-Cohen approximation, and then the thermal expansion coefficients and heat capacity at constant pressure were predicted using the Debye model. The predicted thermal expansion coefficients and heat capacities of cerium oxide are in good agreement with the experimental values.