THE MECHANISM of crystal dissolution involving the movements of monatomic height ledges on a crystal surface was first presented by Burton, Cabrera and Frank.1 This mechanistic approach to the rate of crystal dissolution was further extended by Cabrera and Levine2 and Ives and Hirth3 who considered the rate-determining step to be the nucleation of dissolution ledges (a) at screw dislocations, (b) at edge dislocations, or (c) on perfect singular surfaces. The thermodynamic driving force, represented by the solution undersaturation required for nucleation of ledges at the above sources, increases in the order listed. Dissolution proceeds by the transfer of atoms from kink sites along dissolution ledges into the environment, resulting in a recession of monatomic ledges across a crystalline surface. This mechanistic approach relates the dissolution rate to the velocity of ledge propagation and to the ledge spacing (y).
Based on the classical concepts of Volmer,4...
