Crystal Growth and Renucleation

ABSTRACT

Crystal Growth and Renucleation – Theory and Experiments

Ingo H. Leubner, Journal of Imaging Science and Technology, 37(5):510-516 (1993)

Renucleation is the formation of new crystals when the reactant addition rate during precipitations exceeds the maximum growth rate of a growing (‘seed’) crystal population. This condition is generally unwanted in crystal production, and knowledge of conditions that lead to renucleation is needed for precipitation control. The study of renucleation allows determining this maximum growth rate, which is the critical crystal property that controls renucleation.

A quantitative theory for renucleation was derived using the concepts of the BNG theory. It relates the number of renucleated crystals, Z, to the reactant addition rate, and to the number (amount), size, surface area, and morphology of the seed crystals. The model predicts that the number of renucleated crystals, Z, increases linearly with addition rate, and decreases linearly with the amount or number of seed crystals. The limiting reaction conditions where renucleation ends and the range of conditions where renucleation does not occur are also quantitatively predicted. From the transition condition where renucleation occurs, the maximum growth rate of the crystals is determined.

The model was experimentally confirmed with renucleation experiments on an octahedral AgBr system. The experimentally determined maximum growth rate was 12.4 A/s (std. Dev. 1.0 A/s) for the reaction conditions.