Estimation of ionic conductivity of CuI through tarnishing studies of copper in iodine atmosphere

The conductivity values of isolated CuI crystal has been reported by a large number of investigators. But the conductivity be-haviour of a growing CuI film on copper has not been explored yet. An attempt has been made in this investigation to provide ionic conductivity values of growing CuI films from the kinetics studies of the film growth process. The conductivity value has been found to be proportional to the square of the partial pressure of iodine in the thinner film range while it is approximately proportional to the square root of the partial pressure in the thicker range. Estimation has been based on the fundamental parabolic equation of Wagner relating the rate constant and conductivity. An analysis of the experimental results indicate that the conductivity value of the growing CuI is of higher magnitude for thicker films than that for the thinner ones.