Simulations of Crystal Dissolution Using Interacting Particles: Prediction of Stress Evolution and Rates at Defects and Application to Tricalcium Silicate

A kinetic Monte Carlo framework is employed to simulate dissolution at the site of screw dislocations at the nanoscale. The rate equations, which govern dissolution, combine together chemical potentials, interfacial free energy, and mechanical stresses arising from a position-dependent interaction potential. The simulations are applied to tricalcium silicate dissolution, over a range of solution saturations ranging from pure water to near-equilibrium conditions. The results predict the evolution of topography and stress field during dissolution as well as a sigmoidal relationship between dissolution rates and a solution saturation index, which is compared to experimental results from the literature. The simulations capture the experimentally observed transition between different dissolution mechanisms at a critical saturation index and link it to dissolution at terrace ledge defect sites. Additional results clarify how the critical saturation index depends on the solid-solution interfacial energy of tricalcium silicate. Best fitting of experimental results is achieved with an interfacial energy of 280-350 mJ/m(2), a standard state activation energy of 20-40 kJ/mol, and an apparent activation energy of 25-45 kJ/mol. With their ability to investigate chemomechanical effects, the simulations presented here can help to understand and engineer the dissolution rates of materials.