Determination of parameters of surface mass transport of Ni on sapphire from the kinetics of morphological change of beaded films caused by evaporation

Basic parameters of surface mass transport of Ni on alumina - the surface diffusion length of adatoms, lambda(s), the surface diffusion coefficient, D-s' and the surface reaction rate coefficient, beta(s)' are determined in the temperature range 1298-1443 K, Measuring simultaneously the time dependence of the effective thickness, H-eff(t), the lateral shift of the boundary, y(t) of beaded films (BF) and using vapour pressure data we concluded that the process is controlled by surface reaction at the perimeters of beads. Supposing Arrhenius-type temperature dependence of D-s', beta(s)' and lambda(s) the activation energies and preexponential factors have been calculated.