We have studied how different growth conditions, namely, oxygen flow rate, annealing temperature and annealing time affect the diameter, aspect ratio and number density of CuO nanorods using scanning and transmission electron microscopy. CuO nanorods are synthesized by thermal annealing of thin copper foil. It is observed that while the diameter and number density of nanorods depend critically on the oxygen flow rate and annealing temperature, the aspect ratio and dispersion in diameter of nanorods can mostly be improved by thermal annealing for extended time periods. The growth mechanism of the nanorods is inferred from the evolution of observed microstructural changes. It is proposed that the growth of nanorods takes place from triangular shaped pyramids due to the relaxation of stress accumulated in oxide film during the process of oxidation and annealing.

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Hematite (α-Fe2O3) nanowires have been synthesized on a large surface area by thermal oxidation of iron foil in an ozone-rich environment. The effects of annealing time, temperature, and oxidizing environment on the growth of nanowires have been systematically studied. The samples were characterized using scanning electron microscope (SEM), transmission electron microscope (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). It was found that annealing in ozone-rich environment for 2–4 h at 700 °C yielded the best results in terms of number density and diameter of nanowires. The average diameter of the nanowires was found to be 85 nm. It was found that nanowires are bicrystal in nature with a length around 4 μm, which grows uniquely along the [110] direction.

A study of silver, chromium, stainless-steel, and indium thin films prepared by subnanosecond laser deposition in vacuum is reported. We compare the laser ablation in vacuum at the weak- and tight-focusing conditions of a Ti:sapphire laser beam and analyze the nanoparticles synthesized in the latter case using absorption spectroscopy, x-ray fluorescence, atomic force microscopy, and scanning electron microscopy. Our results show that the nanoparticle formation can be accomplished using long laser pulses under tight-focusing conditions.

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