Impurity trapping during crystal growth

A computer simulation of dendritic crystal growth was developed and used to derive a relationship between solution-trapping and system and process parameters during crystal growth. The relation predicts that trapping will increase with increasing crystal growth velocity and decreasing positive and negative temperature gradients.
A flow crystallizer was used to experimentally study the growth of CaSoٖ₄, potassium aluminum sulfate, and NaCl from aqueous solution. Significant amounts of trapped water (up to 90 mole percent) were found in all systems. These data as well as data from the literature for organic, metallic, and inorganic systems were used to test the computer-derived relation which was found to correlate the data well.
The computer simulation was also used to simulate experiments for compounds that have been experimentally studied. The results for the constants in the predictive equation were within an order-of-magnitude of those obtained from experimental data.