Stress-induced wurtzite to hexagonal phase transformation in zinc oxide nanowires

The stress-induced wurtzite to hexagonal phase transformation in [011̄0] oriented zinc oxide nanowires were investigated using a molecular dynamics simulation and reactive force field potentials. The yield strength of the 2.13×1.93 nm wurtzite nanowires is 12 GPa at 50 K. The wurtzite to hexagonal phase transformation was successfully observed at stress plateaus (5-5.5 GPa at 50 K) located after the yield point of the wurtzite phase. The wurtzite to hexagonal phase transformation was a result of the propagation of {01̄11} twinning boundaries. During the phase transformation, the wurtzite and hexagonal phases were clearly separated by the {01̄11} twinning boundaries. To analyze the difference between ceramic and metallic systems, all the calculation data of wurtzite to hexagonal transformation were compared with stress-induced phase transformation in metallic nanowires such as CuZr and NiAl. As the result of the [011̄0] tensile loading of the ZnO nanowires, the hexagonal phase was obtained.