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Evolution of ferroelectricity in tetrathiafulvalene-p-chloranil as a function of pressure and temperature

Journal Article · · Journal of Chemical Physics
DOI:https://doi.org/10.1063/1.4884964· OSTI ID:22311389
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  1. 1. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart (Germany)
The neutral-to-ionic phase transition in the mixed-stack charge-transfer complex tetrathiafulvalene-p-chloranil (TTF-CA) has been studied by pressure-dependent infrared spectroscopy up to p = 11 kbar and down to low temperatures, T = 10 K. By tracking the C=O antisymmetric stretching mode of CA molecules, we accurately determine the ionicity of TTF-CA in the pressure-temperature phase diagram. At any point, the TTF-CA crystal bears only a single ionicity; there is no coexistence region or an exotic high-pressure phase. Our findings shed new light on the role of electron-phonon interaction in the neutral-ionic transition.
OSTI ID:
22311389
Journal Information:
Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 24 Vol. 140; ISSN JCPSA6; ISSN 0021-9606
Country of Publication:
United States
Language:
English