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Updated: Feb 20, 2026
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Concomitant polymorphism and the martensitic-like transformation of an organic crystal
Michael T Ruggiero1, J Axel Zeitler2, Timothy M Korter3
1Department of Chemistry, Syracuse University, 1-014 Center for Science and Technology, Syracuse, NY 13244-4100, USA. tmkorter@syr.edu and Department of Chemical Engineering and Biotechnology, University of Cambridge, Philippa Fawcett Drive, Cambridge, CB3 0AS, UK.
Abstract:
Crystalline polymorphism is a phenomenon that occurs in many molecular solids, resulting in a diverse range of possible bulk structures. Temperature and pressure can often be used to thermodynamically control which crystal form is preferred, and the associated transitions between polymorphic phases are often discontinuous and complete. N-Methyl-4-carboxypyridinium chloride is a solid that undergoes an apparent continuous temperature-dependent phase transition from an orthorhombic to a monoclinic polymorph. However, a hybrid characterization approach using single-crystal X-ray diffraction, terahertz time-domain spectroscopy, and solid-state density functional theory reveals the transformation to be actually a slowly changing ratio of the two discrete polymorphic forms. The potential energy surface of this process can be directly accessed using terahertz radiation, and the data show that a very low barrier (43.3 J mol-1) exists along the polymorph transformation coordinate.
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