Mechanics Modeling and the Structural Relaxation Effect on ZnO Nanowires

Molecular dynamics simulations of ZnO nanowires (NWs) [22] show that the structural relaxation (SR) leads to the distribution of Young's modulus (Y) different from the assumption of the core-shell (C-S) model. It is thus of interest to validate the C-S model in measuring the equivalent Young's modulus and evaluate the effect of SR on the piezoelectric potential of bent ZnO NWs. To this end, a layer-wise model with the actual Y- distribution is developed and compared with the C-S model in the virtual experiments performed via the finite-element simulations. It is found that, in the tensile test, the C-S model can still be used to predict the Young's modulus as it happens to reflect a quadratic polynomial law of the SR-induced excess strain energy density. In addition, the strong effect of SR is achieved for the piezoelectric potential of the bent NWs, where the redistributed piezoelectric property plays a predominant role.