Growth mechanism and magnetic properties of highly crystalline NiO nanocubes and nanorods fabricated by evaporation

A new approach to the preparation of regularly shaped NiO nanocubes and nanorods by an infrared heating evaporation method is presented. The growth model is proposed to be a vapor−solid mechanism. The morphology of the nanocrystals can be tuned by the carrier gas flow rate. The samples consist of nanocrystals that are highly crystallized with atomic-scale smooth surfaces. This novel method could be extended to nanocrystal growth of other oxides with low volatility or high melting points. The results of magnetic characterization indicate that the NiO nanorods and nanocubes grown from a mixed target both show weak ferromagnetic states at low and room temperature due to uncompensated spins at the surfaces of the nanocrystals.