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Kohara, Shinji*; Suzuya, Kentaro; Takeuchi, Ken*; Loong, C.-K.*; Grimsditch, M.*; Weber, J. K. R.*; Tangeman, J. A.*; Key, T. S.*
Science, 303(5664), p.1649 - 1652, 2004/03
Times Cited Count：159 Percentile：96.06(Multidisciplinary Sciences)Inorganic glasses normally exhibit a network of interconncted covalent-bonded structural elements that has no long-range order. In silicate glasses the network formers are based on SiO
-tetrahedra interconnected via oxygen atoms at the corners. Conventional wisdom then implies that alkaline and alkaline-earth orthosilicate materials cannot be vitrified because they do not contain sufficient network forming SiO
to establish the needed interconnectivity. We have studied a bulk magnesium orthosilicate glass obtained by containerless melting-and-cooling. We find that the role of network former is 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 novel glassy phases may be found in the containerless environment of interstellar space.
SiO
Weber, J. K. R.*; Tangeman, J. A.*; Key, T. S.*; Loong, C.-K.*; Takeuchi, Ken*; Suzuya, Kentaro
Physics and Chemistry of Glasses, Vol.43C 2002, p.68 - 70, 2002/00
The structure of olivine-composition glasses is of considerable interest in both geology and glass-science. Olivine is one of the most common minerals in the Earth's upper mantle, and properties of olivine-rich melts are relevant to a variety of petrologic problems. Despite their prevalence and novelty, such glasses has not been studied thoroughly due to difficulties associated with their synthesis. Recently, Weber et al successfully prepared bulk olivine glass with the forsterite-composition MgSiO using a containerless technique and initiated a neutron-diffraction investigation of the short-range structure of the glass. In this study, we present a result of the pulsed neutron diffraction experiment on the forsterite-composition glass. The neutron diffraction analysis suggests that highly distorted MgO
polyhedra are the major networking structural units in the forsterite-composition glass.
