Synthesis and growth twinning of γ-Al2O3 nanowires by simple evaporation of Al-Si alloy powder

In this study, single-crystalline gamma-Al2O3 nanowires were synthesized by simple evaporation of Al-Si alloy source powder at 1070 degrees C under different working pressures. The structures and growth mechanisms of the nanowires were examined. Under a low working pressure of 0.5 torr, uniform nanowires with a catalyst particle were synthesized by a vapor-liquid-solid mechanism and grew along a [2-20] direction. Twinning occurred parallel to nanowire growth direction and a twin angle of 15.5 degrees/164.5 degrees was identified. As the pressure increased, zigzag nanowires without a catalyst grew along a [-1-11] direction alternatively via a vapor-solid route. Twinning also formed with an angle of 15.5 degrees/164.5 degrees. Perpendicular twinning planes to the growth direction induced the deflected feature of the nanowires.