Polymorph evolution during crystal growth studied by 3D electron diffraction
Edward T. Broadhurst,
Hongyi Xu,
Max T. B. Clabbers,
Molly Lightowler,
Fabio Nudelman,
Xiaodong Zou,
Simon Parsons
Affiliations
Edward T. Broadhurst
EaStCHEM School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3FJ, UK
Hongyi Xu
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-106 91, Sweden
Max T. B. Clabbers
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-106 91, Sweden
Molly Lightowler
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-106 91, Sweden
Fabio Nudelman
EaStCHEM School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3FJ, UK
Xiaodong Zou
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm SE-106 91, Sweden
Simon Parsons
EaStCHEM School of Chemistry and Centre for Science at Extreme Conditions, The University of Edinburgh, King's Buildings, West Mains Road, Edinburgh EH9 3FJ, UK
3D electron diffraction (3DED) has been used to follow polymorph evolution in the crystallization of glycine from aqueous solution. The three polymorphs of glycine which exist under ambient conditions follow the stability order β < α < γ. The least stable β polymorph forms within the first 3 min, but this begins to yield the α-form after only 1 min more. Both structures could be determined from continuous rotation electron diffraction data collected in less than 20 s on crystals of thickness ∼100 nm. Even though the γ-form is thermodynamically the most stable polymorph, kinetics favour the α-form, which dominates after prolonged standing. In the same sample, some β and one crystallite of the γ polymorph were also observed.
