Polymorphism is the capacity of a solid material to exist in more than one crystal structure (where here we take this definition to include elemental polymorphism, or allotropy). Often changes in crystal structure can lead to new properties and the opening up of the range of potential applications of a single compound (e.g. two different polymorphs of BN can be used an an abrasive or a lubricant respectively). The number of naturally occurring metastable polymorphs for any one inorganic compound is relatively scarce and typically amounts to a handful of crystal structures at most. Synthesis of metastable inorganic polymorphs is also difficult, due the high temperatures typically employed in solid state inorganic synthesis which tends to produce the most thermodynamically stable crystal structure. High-pressure techniques provide a means to obtain new dense polymorphs, which are, however, often difficult to quench to ambient conditions.

Over the last few decades numerous theoretical predictions and new experimental synthesis (e.g. low temperature deposition [1], novel templating methods [2], degassing of high pressure phases [3]) have begun to expand the world of novel metastable polymorphs. Often the collaboration of both theoreticians and experimentalists has been crucial for these advances. In order to further encourage a productive cross fertilization of predictive theory and new experimental methods we propose a workshop where both groups can meet in order to facilitate the exchange and creation of new ideas. We hope that this meeting will help initiate collaborations among researchers with the necessary skills to push forward this exciting interdisciplinary field.

[1] Experimental Substantiation of the “Energy Landscape Concept” for Solids: Synthesis of a New Modification of LiBr, Y. Liebold-Ribeiro, D. Fischer, M. Jansen, Angew. Chem. Int. Ed. 47. 4428 (2008)
[2] Supramolecular self-assembled molecules as organic directing agent for synthesis of zeolites, A. Corma, F. Rey, J. Rius, M. J. Sabater, S. Valencia, Nature 431, 287-290 (2004).
[3] Synthesis of an open-framework allotrope of silicon, D. Y. Kim, S. Stefanoski, O. O. Kurakevych, T. A. Strobel, Nature Materials, 14, 169, (2015)