title: Glass formation at the limit of insufficient network formers.
abstract: 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.
authors.affiliation: Japan Synchrotron Radiation Research Institute, Mikazuki, Sayo, Hyogo 679-5198, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Kohara
authors.forename: K
authors.initials: K
authors.lastname: Suzuya
authors.forename: K
authors.initials: K
authors.lastname: Takeuchi
authors.forename: C K
authors.initials: CK
authors.lastname: Loong
authors.forename: M
authors.initials: M
authors.lastname: Grimsditch
authors.forename: J K R
authors.initials: JK
authors.lastname: Weber
authors.forename: J A
authors.initials: JA
authors.lastname: Tangeman
authors.forename: T S
authors.initials: TS
authors.lastname: Key