Kinetic laws of thermal transformations in nickel nanofilms

Transformations in nickel nanofilms as a function of thickness (d = 3–60 nm) and temperature of heat treatment (T = 373–873 K) are studied via optical spectroscopy, microscopy, and gravimetry. It is found that, depending on the thickness of nickel films and temperature of heat treatment, the kinetic curves of the degree of transformation are satisfactorily described in terms of the linear, inverse logarithmic, cubic, and logarithmic laws. The contact potential difference for Ni and NiO films and the photovoltage for Ni-NiO systems are measured. An energy band diagram for Ni-NiO systems is constructed. A model of the thermal transformation of Ni films, including the stages of oxygen adsorption, charge carrier redistribution in a Ni-NiO contact field, and the formation of nickel(II) oxide, is proposed.