Formation and microstructure of nickel oxide films

Abstract

The formation and microstructure of NiO films on different substrates were monitored using XRD, Raman, UV/Vis/NIR and FE–SEM/EDS techniques. The formation of NiO films on Ni plates in air atmosphere between 400 and 800°C was confirmed by XRD and Raman spectroscopy. The origin of Raman bands and corresponding Raman shifts in the samples are discussed. An increase in the size of NiO particles in the films from nano to micro dimensions was demonstrated. A change in the atomic ratio Ni:O with an increase in heating temperature was observed. Polished Ni plates coated with a thin Ni-acetate layer upon heating at high temperatures gave similar NiO microstructures on the surface like in the case of non-treated Ni plates. Glass substrates coated with thin Ni-acetate films upon heating between 400 and 800°C yielded pseudospherical NiO nanoparticles. The dominant Raman band as an indicator of NiO formation on a glass substrate was shown. The formation of NiO nanoparticles on glass substrates with maximum size distribution from 16 to 27nm in a broad temperature range from 400 to 800°C can be explained by the absence of a constant source of metallic nickel which was present in the case of Ni plates.