Novel phase transformation in ZnO nanowires under tensile loading.

We predict a previously unknown phase transformation from wurtzite to a graphitelike (P6(3)/mmc) hexagonal structure in [0110]-oriented ZnO nanowires under uniaxial tensile loading. Molecular dynamics simulations and first principles calculations show that this structure corresponds to a distinct minimum on the enthalpy surfaces of ZnO for such loading conditions. This transformation is reversible with a low level of hysteretic dissipation of 0.16 J/m3 and, along with elastic stretching, endows the nanowires with the ability to recover pseudoelastic strains up to 15%.