A Density Functional Study of Zinc Oxide Elastic Properties Under High Pressure

Abstract

AbstractZinc Oxide (ZnO) material has been widely used in piezoelectric devices, electro-optic devices, and biomedical sensors, etc. Among three crystal phases, ZnO with wurtzite structure (B4) is most common; thus it usually exists in natural ZnO materials. ZnO with zinc blend structure (B3) is another common crystal phase, which is metastable in nature. As observed by researchers, ZnO materials synthesized by chemical vapor deposition (CVD), which is one of the most popular methods to synthesize nanomaterials, have both B3 and B4 structures. In this paper, we discussed the elasticity and crystal structure of ZnO with the two structures under high pressure from 0 to 10 GPa. The CAmbridge Serial Total Energy Package (CASTEP) based on density functional theory (DFT) was used to perform the calculations. Both local density approximation (LDA) and generalized gradient approximation (GGA) were employed for comparison. We found that all the lattice constants decreased with the increasing pressure, and the relationship was linear, while the bulk moduli increased with the increasing environment pressure. However, the elastic constants (including C11, C12 and C44 for B3; C11, C12, C13, C33 and C44 for B4) showed a more sophisticated trend, which could be attributed to the particular symmetry of the crystal structure. The elastic constants denoting the elasticity of longitudinal directions would become larger with the increasing pressure, while the others show irregular trends. The results in this paper will be helpful in widening the application of devices based on ZnO nanomaterials.KeywordsZnOElastic propertiesDensity functional theory (DFT)Multi-scale simulation