TY - JOUR A1 - Schlegel, Moritz-Caspar A1 - Grzimek, V. A1 - Günther, G. A1 - Svetogorov, R. A1 - Veziri, C. M. A1 - Kapsi, M. A1 - Karanikolos, G. N. A1 - Prokhnenko, O. A1 - Bewley, R. A1 - Russina, M. T1 - Explaining water adsorption in one-dimensional channels in AlPO4-5 on molecular scale JF - Microporous and Mesoporous Materials N2 - The adsorption of water in one-dimensional channels in porous aluminophosphate material AlPO4-5 has been studied by a combination of gravimetric Analysis techniques, neutron and X-ray diffraction and Neutron spectroscopy. Molecular structure of AlPO4-5 consists of 12-membered rings of alternating, corner-sharing AlO4 and PO4 tetrahedra connected by oxygen bridges into sheets in the (a, b) plane. The sheets are connected by oxygen bridges along the c crystal axis and form onedimensional channels of which the largest, formed by the 12-membered rings, have a van der Waals Diameter of about 8.3 Å. Gradually increasing the amount of adsorbed water we could follow the evolution of the confined water mobility in a systematic way and identify the molecular mechanism of water adsorption. We focused particularly on the range of low and medium relative pressures up to p/p0=0.32, where a Change from a hydrophobic behavior to a steep, capillary condensation like water intake has been observed. At the Initial adsorption stages water occupies positions close to the pore walls causing the contraction of channels in the (a, b) plane and the prolongation of the channels along c axis in AlPO4-5. With the progressing intake water molecules form chains along the main channels. The cooperative interactions between water molecules lead to the onset of phonon-like cooperative modes and, surprisingly, to the increase of diffusive-like motion, which slow down only in the final adsorption stages when AlPO4-5 channels are completely filled. KW - AlPO4-5 KW - Water adsorption KW - Confined water KW - 1-dimensional, KW - Diffusion PY - 2018 DO - https://doi.org/10.1016/j.micromeso.2018.11.025 SN - 1387-1811 VL - 304 SP - 109201 PB - Elsevier Inc. AN - OPUS4-46798 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Russina, M. A1 - Gunther, G. A1 - Grzimek, V. A1 - Schlegel, Moritz-Caspar A1 - Veziri, C. M. A1 - Karanikolos, G. N. A1 - Yamada, T. A1 - Mezei, Ferenc T1 - Nanoscale Dynamics and Transport in Highly Ordered Low-Dimensional Water JF - The Journal of Physical Chemistry Letters N2 - Highly ordered and highly cooperative water with properties of both solid and liquid states has been observed by means of neutron scattering in hydrophobic one-dimensional channels with van der Waals diameter of 0.78 nm. We have found that in the initial stages of adsorption water molecules occupy niches close to pore walls, followed later by the filling of the central pore area. Intensified by confinement, intermolecular water interactions lead to the formation of well-ordered hydrogen-bonded water chains and to the onset of cooperative vibrations. On the other hand, the same intermolecular interactions lead to two relaxation processes, the faster of which is the spontaneous position exchange between two water molecules placed 3.2-4 A from each other. Self-diffusion in an axial pore direction is the result of those spontaneous random exchanges and is substantially slower than the self-diffusion in bulk water. KW - Hydrophobic confinement KW - Neutron scattering KW - Water dynamics PY - 2019 DO - https://doi.org/10.1021/acs.jpclett.9b02303 VL - 10 IS - 20 SP - 6339 EP - 6344 PB - ACS Publications AN - OPUS4-49257 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -