Deducing primary nucleation parameters from metastable zone width and induction time data determined with simulation

Abstract

Metastable zone widths (MSZWs) and induction times were determined with numerical simulations on an unseeded aqueous solution. The simulated MSZWs and induction times were significantly affected by secondary nucleation caused by nuclei grown crystals. However, this secondary nucleation-mediated effect on the MSZWs and induction times was negligibly small at high cooling rates and at high supercoolings, respectively. The primary nucleation parameters k_b1 and b1 in the rate expression B₁ = k_b1(ΔT)^b1, where B₁ is the nucleation rate and ΔT is supercooling, were deduced by applying mathematical Kubota models to the determined MSZWs and induction times, respectively. Correct primary nucleation parameters (i.e., the same values as those input for the simulations) were deduced only under the condition of neglected secondary nucleation. The simulation results suggest that, in actual experiments, the proper primary nucleation parameters b1 and k_b1 can be deduced from the MSZWs and induction times if these were measured under the condition of neglected secondary nucleation. In addition, an experiment with a slow stirrer speed (low secondary nucleation rate) and with a high sensitivity detector (earlier detection of the MSZW and induction time) were recommended for the deduction of correct primary nucleation parameters.