Atomistic modeling of Phase transformation in ZnO nanorods

Molecular dynamic simulations are performed to systematically investigate the structural mechanical properties of ZnO nanorods (NRs) using the empirical Buckingham potential. The considered NRs have hexagonal cross-sections with lateral dimension ranging from 1-10nm and constant length 10.4 nm. Different from its bulky counterpart, the results show that ZnO NRs undergo a size dependent four-stage deformation process: elastic stretching of initial Wurtzite structure, Wurtzite to body-centered tetragonal (BCT-4) phase transformation, stretching of the resulting BCT-4 structure and eventually brittle fracture. The critical stress for phase transformation decreases while the critical strain increases with increasing the NR size. The analyses indicate that the size dependency of phase transformation is dominated by the size effect on the Young’s modulus.