In Situ 3D Crystal Growth Measurement: Unravelling the Nature of Crystal Face-Specific Growth Rate Dispersion in α-Form l-Glutamic Acid

Obtaining 3D crystal morphology and its evolution during growth is beneficial for crystallization process design. A newly developed image analysis tool is used to reconstruct the complex 3D morphology (20 habit faces in 6 forms) of α form l-glutamic acid crystals from 2D transmission microscopy images captured in situ during the growth process. A digital crystallographically based polyhedral mesh is fitted to experimental images, enabling calculation of face-specific growth rates. Solution supersaturation during the growth process is estimated using the fitted crystal volume together with solubility and density data. The data reveals significant growth rate dispersion, reflecting differences in the local solution environment, with {110} and {100} faces growing fastest and {001} the slowest. For our experiments, mechanistic analysis is consistent with surface integration-limited growth, which aligns with the BCF model, except for the {111} and {001} surfaces, which are mass transfer limited under the B&S model.