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.