The effect of emergent dislocations on the kinetics of decomposition of solid surfaces under conditions of chemical reaction control

Abstract

Using a simplified model of an oxide surface containing emergent dislocations, it has been shown that the overall chemical reaction rate constant for the reduction of an iron oxide reaction surface varies during the initial period of oxygen removal due to the increase in the number of reaction sites. The removal of any effective barrier to ledge formation ensures that the maximum number of reaction sites eventually becomes active,i.e., the maximum chemical reaction rate constant is achieved. The transient time or time to achieve the maximum rate constant has been shown to depend on the ledge velocity, which is directly related to the chemical reaction rate per reaction site, and the number of dislocation sources per unit area on the surface. The form of the transient and the transient time are estimated using a simple nucleation and growth model.