Characterization of Ni nanowires after annealing

The effect of Ni nanowires, fabricated by electrodeposition in self-ordered AAO templates, was studied. NiO and Ni2O3 nanofibers were fabricated by simple heat-treatment in air and in an atmosphere of pure O2. Ni nanowires after vacuum annealing exhibit pronounced preferential orientation of Ni (111) at 600 °C. Grain growth resulted in size effects and induced the transformation of NiO to Ni2O3 during annealing in air. Ni was oxidized to Ni2O3 (∼ 500 °C) in an atmosphere of pure O2. The stable Ni-oxides Ni2O3 are formed during annealing at a higher temperature (∼ 900 °C) in air and in an atmosphere of pure O2.