Gas-sensing properties of needle-shaped Ni-doped SnO2 nanocrystals prepared by a simple sol-gel chemical precipitation method.

The preparation of needle-shaped SnO(2) nanocrystals doped with different concentration of nickel by a simple sol-gel chemical precipitation method is demonstrated. By varying the Ni-dopant concentration from 0 to 5 wt%, the phase purity and morphology of the SnO(2) nanocrystals are significantly changed. Powder XRD results reveal that the SnO(2) doped with a nickel concentration of up to 1 wt% shows a single crystalline tetragonal rutile phase, whereas a slight change in the crystallite structure is observed for samples with nickel above 1wt%. High resolution scanning electron microscopy (HRSEM) results reveal the change in morphology of the materials from spherical, for SnO(2), to very fine needle-like nanocrystals, for Ni-doped SnO(2), annealed at different temperatures. The gas sensing properties of the SnO(2) nanocrystals are significantly enhanced after the nickel doping.