Heterogeneous 2D nucleation of the stable polymorphic form on the metastable form

For the determination of the metastable zone width, that is the supersaturation needed to observe nucleated crystals in a given time, it is essential to have control of which polymorph is formed. For heterogeneous nucleation, the metastable zone width can be significantly lowered. This paper discusses a special case of heterogeneous nucleation for which the stable phase of a steroid nucleates on specific faces of the metastable one. (C) 2004 Elsevier B. V. All rights reserved.