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Updated: Mar 24, 2026

Orientational Transition in a Liquid Crystal Triggered by the Thermodynamic Growth of Interfacial Wetting Sheets
Published on: May 15, 2017
Symmetry Switching of Negative Thermal Expansion by Chemical Control
Mark S Senn1, Claire A Murray2, Xuan Luo3
1Department of Chemistry, University of Oxford , Inorganic Chemistry Laboratory, South Parks Road, Oxford, OX1 3QR, U.K.
Abstract:
The layered perovskite Ca3-xSrxMn2O7 is shown to exhibit a switching from a material exhibiting uniaxial negative to positive thermal expansion as a function of x. The switching is shown to be related to two closely competing phases with different symmetries. The negative thermal expansion (NTE) effect is maximized when the solid solution is tuned closest to this region of phase space but is switched off suddenly on passing though the transition. Our results show for the first time that, by understanding the symmetry of the competing phases alone, one may achieve unprecedented chemical control of this unusual property.
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