First-principles investigations on the elastic and thermodynamic properties of cubicZrO2under high pressure

We have investigated the elastic and thermodynamic properties ofZrO2under pressure up to 120 Gpa by the plane wave pseudopotential density functional theory with the generalized gradient approximation (GGA) method. The elastic constants ofZrO2are calculated and meet the generalized stability criteria, suggesting thatZrO2is mechanically stable within this pressure range. The pressure effects on the elastic properties reveal that the elastic modulusB, shear modulusGand Young's modulusYincrease linearly with the pressure increasing, implying that the resistance to deformation is enhanced. In addition, by analyzing the Poisson's ratio ν and the value ofB/G, we notice thatZrO2is regarded as being a ductile material under high pressure and the ductility can be improved by the pressure increasing. Then, we employ the quasi-harmonic Debye model considering the phononic effects to obtain the thermodynamic properties ofZrO2. Debye temperatureΘD, thermal expansion coefficient α, heat capacityCpand Grüneisen parameter γ are systematically explored at pressure of 0–80 Gpa and temperature of 0–1000 K. Our results have provided fundamental facts and evidences for further experimental and theoretical researches.