KINK DENSITIES ALONG A CRYSTAL-SURFACE STEP AT LOW-TEMPERATURES AND UNDER NONEQUILIBRIUM CONDITIONS

The kink density along a (01) step on the (001) face of a Kossel crystal is derived from a kinetic steady state approach by considering the elementary events at the step. When the thermal energy kT is small compared with the kink formation energy ε{lunate}, the kink density, ρ{variant}, is found to be a function of the saturation ratio, S. For S>1, ρ{variant} = 2a-1S 1 2 exp(-ε{lunate}/kT), whil S <1, ρ{variant} = 2a-1 exp(-ε{lunate}/kT)/(2-S) 1 2. At S = 1, both equations reduce to the expression obtained by statistical thermodynam arguments. The limiting rate laws for growth and dissolution of a vicinal surface with steps originating from a screw dislocation are also obtained. The current finding may provide a theoretical background for interpreting the observed growth and dissolution kinetics for many sparingly soluble salts in aqueous solutions. © 1990.