Liu, Huiyu and Zhang, Weiguo and Halasyamani, P. Shiv and Stokes, Harold T. and Campbell, Branton J. and Evans, John S. O. and Evans, Ivana Radosavljevic (2018) 'Understanding the behaviour of the above-room-temperature molecular ferroelectric 5,6-dichloro-2-methylbenzimidazole using symmetry adapted distortion mode analysis.', Journal of the American Chemical Society., 140 (41). pp. 13441-13448.
The exploitable properties of many functional materials are intimately linked with symmetry-changing phase transitions. These include properties such as ferroelectricity, second harmonic generation, conductivity, magnetism and many others. We describe a new symmetry-inspired method for systematic and exhaustive evaluation of the symmetry changes possible in molecular systems using molecular distortion modes, and how different models can be automatically tested against diffraction data. The method produces a quantitative structural landscape from which the most appropriate structural description of a child phase can be chosen. It can be applied to any molecular or molecular-fragment containing material where a (semi) rigid molecule description is appropriate. We exemplify the method on 5,6-dichloro-2-methylbenzimidazole (DC-MBI), an important molecular ferroelectric. We show that DC-MBI undergoes an unusual symmetry-lowering transition on warming from orthorhombic Pca21 (T ≲ 400 K) to monoclinic Pc. Contrary to expectations, the high temperature phase of DC-MBI remains polar.
|Full text:||(AM) Accepted Manuscript|
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|Publisher Web site:||https://doi.org/10.1021/jacs.8b08591|
|Publisher statement:||This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/jacs.8b08591.|
|Date accepted:||19 September 2018|
|Date deposited:||16 October 2018|
|Date of first online publication:||19 September 2018|
|Date first made open access:||19 September 2019|
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