Dresden 2017 – wissenschaftliches Programm
CPP 37.8: Vortrag
Mittwoch, 22. März 2017, 12:30–12:45, ZEU 255
Incipient Ferroelectricity of Nano-Confined Water Molecules — Boris Gorshunov1,2, Elena Zhukova1,2, Mikhail Belyanchikov2, Victor Thomas3, Pavel Tomas4, Maxim Savinov5, Christelle Kadlec5, and •Martin Dressel1 — 11. Phys. Inst., Univ. Stuttgart, Germany — 2MIPT, Dolgoprudny, Russia — 3Inst. Geol. Mineral., Novosibirsk, Russia — 4Indep. Univ. Moscow, Russia — 5Czech Acad. Sci., Praha, Czech Republic
Although H2O molecules exhibit an extremely large electrical dipole moment, neither liquid water nor ice are ferroelectric since short-range hydrogen bonds screen the long-range intermolecular dipole-dipole coupling. The situation changes drastically when water is confined on the nanoscale. Though theoretically predicted and simulated, the H2O ferroelectric ordering has never been clearly observed experimentally.
We have placed H2O in the matrix of a beryl crystal lattice where the single water molecules are separated far enough from each other to avoid hydrogen bonds, but close enough to retain the dipole-dipole interaction. Using broad-band dielectric spectroscopy we demonstrate incipient ferroelectricity within the ensemble of interacting water molecules: on cooling, the static permittivity increases according to the Curie-Weiss law as a ferroelectric soft mode develops in the THz frequency range. At low temperatures quantum fluctuations eventually suppress the ferroelectric phase transition and lead to a saturation of the soft mode parameters and of the static permittivity. We model the results with the approach of a ferroelectric orientational phase transition.