Microstrain in nanostructured nickel oxide studied using isotropic and anisotropic models

Nanostructured nickel oxide, NiO is synthesized through a novel chemical route using nickel chloride and ethanol amine as starting materials. The prepared samples are annealed at higher temperatures, viz. 350 degrees C, 400 degrees C, 500 degrees C and 600 degrees C. The samples are characterized using XRD, TEM, antioxidant activity and DC conductivity measurements. The crystallite size and microstrain in the samples are studied using Williamson-Hall (W-H) analysis assuming uniform deformation model, uniform deformation stress model and uniform deformation energy density model. The results obtained using three models yield microstrain values which decreases with increase of crystallite size. The average crystallite size and the microstrain of the samples measured from modified W-H plot using uniform energy density model are found to be most suitable. The study shows that the microstrain in nanostructured NiO originates due to the presence of Ni2+ and O2- vacancies and it is confirmed by the measurement of antioxidant activity and dc conductivity of the samples in vacuum and air ambience. (C) 2013 Elsevier B.V. All rights reserved.