Quasi-one-dimensional water encapsulated inside single-walled carbon nanotubes, here referred to as nanotube water, was studied by neutron scattering. The results reveal an anomalously soft dynamics characterized by pliable hydrogen bonds, anharmonic intermolecular potentials, and large-amplitude motions in nanotube water. Molecular dynamics simulations consistently describe the observed phenomena and propose the structure of nanotube water, which comprises a square-ice sheet wrapped into a cylinder inside the carbon nanotube and interior molecules in a chainlike configuration.
Inorganic glasses normally exhibit a network of interconnected, covalent-bonded, structural elements that has no long-range order. In silicate glasses, the network formers are based on SiO4 tetrahedra interconnected through oxygen atoms at the corners. Conventional wisdom implies that alkaline and alkaline-earth orthosilicate materials cannot be vitrified, because they do not contain sufficient network-forming SiO2 to establish the needed interconnectivity. We studied a bulk magnesium orthosilicate glass obtained by containerless melting and cooling. We found that the role of network former was largely taken on by corner and edge sharing of highly distorted, ionic Mg-O species that adopt 4-, 5-, and 6-coordination with oxygen. The results suggest that similar glassy phases may be found in the containerless environment of interstellar space.
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