Abstract
We presented a detailed study on the structure, mechanical properties, and phase stability for three zirconia crystals under hydrostatic pressure of 0-100 GPa by using density functional theory within the generalized gradient approximation. It is found that m-ZrO2 presents three phase transitions with increasing pressure, while t-ZrO2 and c-ZrO2 do not. As the pressure increases, the band gap of m-ZrO2 presents three abrupt changes. The band gap of t-ZrO2 firstly decreases and then increases slowly. The band gap of c-ZrO2 increases monotonically. An analysis of elastic constants shows that the three oxides are anisotropic under compression with increasing pressure. As the pressure increases, their fracture strength and plastic strength are improved and they are all ductile. The calculated formation enthalpies suggest that the elements (Zr + O-2) are able to form m-ZrO2, t-ZrO2, or c-ZrO2 in the whole pressure range, indicating that zirconium and its alloys are easy to be oxidized.