Effect of Ce Substitution on Mechanical and Thermal Properties of Tetragonal YSZ: First-Principles Calculations

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The effect of impurity Ce on the mechanical and thermal properties of tetragonal ZrO2 stabilized by rare earth element Y (YSZ) have been studied using first principles density functional theory within generalized gradient approximation (GGA) for the exchange correlation potential. The predicted elastic constants indicate that YSZ and Ce doped YSZ (CeYSZ) are mechanically stable structures. And then the numerical estimates of bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, sound velocity and minimum thermal conductivity were performed using the calculated elastic constants and analyzed for the first time. The values of sound velocity from different orientations are also reported. The agreement between the results of the available experiments and our calculations was satisfactory. Our calculated results indicate that Young’s modulus, hardness, mean sound velocity and minimum thermal conductivity of YSZ can be decreased by Ce substitution. The reasons are from the “softened” Ce-O bond strength using bond population and relative volume change under external hydrostatic pressure. Chemical bonding nature was also analyzed from the density of states and electron density difference.