A DFT+U study on the thermodynamic properties of defective Gd2Zr2O7 pyrochlore

Abstract

With many technologies and applications downscaling to nanometer dimensions, single point defects can modify the physical properties of compounds significantly, and advancing the fundamental understanding is critical to defect engineering and control of material properties. In the present study, first-principles calculations based on density functional theory (DFT) are carried out to study how the presence of point defects (vacancy, interstitial and antisite) affects the mechanical and thermal properties of Gd2Zr2O7 pyrochlore. As compared with the pure Gd2Zr2O7, the defective states exhibit smaller elastic moduli and better ductility. The Debye temperatures for the defective Gd2Zr2O7 are generally lower than those for pristine compound, indicating that the defective states have larger thermal expansion coefficient. This study suggests that under irradiation the thermomechanical properties of pyrochlores are influenced significantly, and intentional controlling of the point defects may benefit to improve their mechanical stability.