Mechanism of the initial stage of silicate oligomerization.

The mechanism of the initial stage of silicate oligomerization from solution is still not well understood. Here we use an off-lattice kinetic Monte Carlo (kMC) approach called continuum kMC to model silicate oligomerization in water solution. The parameters required for kMC are obtained from density functional theory (DFT) calculations. The evolution of silicate oligomers and their role in the oligomerization process are investigated. Results reveal that near-neutral pH favors linear growth, while a higher pH facilitates ring closure. The silicate oligomerization rate is the fastest at pH 8. The temperature is found to increase the growth rate and alter the pathway of oligomerization. The proposed pH and temperature-dependent mechanism should lead to strategies for the synthesis of silicate-based materials.