Single-particle and collective excitations of polar water molecules confined in nano-pores within a cordierite crystal lattice. Issue 11 (7th March 2022)

• Record Type: Journal Article
• Authors: Belyanchikov, M. A.; Bedran, Z. V.; Savinov, M.; Bednyakov, P.; Proschek, P.; Prokleska, J.; Abalmasov, V. A.; Zhukova, E. S.; Thomas, V. G.; Dudka, A.; Zhugayevych, A.; Petzelt, J.; Prokhorov, A. S.; Anzin, V. B.; Kremer, R. K.; Fischer, J. K. H.; Lunkenheimer, P.; Loidl, A.; Uykur, E.; Dressel, M.; Gorshunov, B.
• Is Part Of: Physical chemistry chemical physics. Volume 24:Issue 11(2022)
• Page Start: 6890
• Page End: 6904
• Publication Date: 2022-03-07
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d1cp05338h
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : Dielectric spectroscopy along with MD and MC simulations was used to study the excitations of nanoconfined water molecules in cordierite nanocages. Abstract : Recently, the low-temperature phase of water molecules confined within nanocages formed by the crystalline lattice of water-containing cordierite crystals has been reported to comprise domains with ferroelectrically ordered dipoles within the a, b -planes which are antiferroelectrically alternating along the c -axis. In the present work, comprehensive broad-band dielectric spectroscopy is combined with specific heat studies and molecular dynamics and Monte Carlo simulations in order to investigate in more detail the collective modes and single-particle excitations of nanoconfined water molecules. From DFT-MD simulations we reconstruct the potential-energy landscape experienced by the H2 O molecules. A rich set of anisotropic temperature-dependent excitations is observed in the terahertz frequency range. Their origin is associated with the complex rotational/translational vibrations of confined H2 O molecules. A strongly temperature dependent relaxational excitation, observed at radio-microwave frequencies for the electric field parallel to the crystallographic a -axis, E || a is analyzed in detail. The temperature dependences of loss-peak frequency and dielectric strength of the excitation together with specific heat data confirm a ferroelectric order–disorder phase transition at T 0 ≈ 3 K in the network of H2 O dipoles. Additional dielectric data are also provided for polarization E || b, too. Overall, these combined experimental investigations enable detailed conclusions concerning the dynamics of the confined water molecules that develop within their microscopic energy landscapes.