Key points are not available for this paper at this time.
We present in-situ observations of the epitaxial nucleation of the metastable polymorph of a steroid on specific faces of the stable form in different solutions using optical microscopy. The polar morphology of the crystals allows for the determination of the specific face where the epitaxial nucleation takes place. The observations prove that there is a different barrier for 2D epitaxial nucleation of the metastable polymorph on the opposite polar faces. In-situ Raman measurements are used to confirm the structure of the epitaxially growing crystals. The metastable zone width and the role of the solvent in this process are discussed. The relatively large lifetime of the metastable polymorph in ethanol solutions is exploited to determine the solubility curves of the bulk phases of both polymorphs. The relation between the solubility of the two polymorphs in different solvents and the polymorphic transformation rate is discussed.
Stoica et al. (Sat,) studied this question.