Dielectric phase transition and symmetry change of constituent molecules in proton–deuteron mixed crystals of squaric acid
In: The Journal of Chemical Physics, Jg. 95 (1991), Heft 4, S. 2244-2251
Online
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Zugriff:
We have investigated effects of random substitution of proton sites with deuterons on the temperature- and pressure-induced phase transitions in squaric acid crystal, which consists of ferroelectrically ordered molecular sheets of [C4O4]2−(SQ2−) skeletons and intervening protons or deuterons. In the isotopically mixed crystals (H1−xDx )2SQ, the critical temperature Tc for the dielectric phase transition was found to increase linearly with the deuterium concentration x, while the critical pressure Pc increases nonlinearly with x at 300 K. Around the pressure ∼20 kbar above Pc, the constituent SQ2− skeletons in the paraelectric phase show a symmetry change from the asymmetric (C1h ) to centrosymmetric (C4h ) form, which is likely caused by the deformation of the correlated proton (deuteron) potential.
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Dielectric phase transition and symmetry change of constituent molecules in proton–deuteron mixed crystals of squaric acid
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Autor/in / Beteiligte Person: | Moritomo, Y. ; Katsufuji, T. ; Tokura, Y. |
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Zeitschrift: | The Journal of Chemical Physics, Jg. 95 (1991), Heft 4, S. 2244-2251 |
Veröffentlichung: | AIP Publishing, 1991 |
Medientyp: | academicJournal |
ISSN: | 0021-9606 |
DOI: | 10.1063/1.460980 |
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