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SiO
glass made by a method for containerless supercooled-liquid-phase processing at high temperaturesKohara, Shinji*; Suzuya, Kentaro; Takeuchi, Ken*
Mirai Zairyo, 5(4), p.28 - 33, 2005/04
We succeeded in producing highly pure glass made of "forsterite," contained in upper mantle of the Earth and meteorites. Although ordinary glass is made of silica network structure, this glass has an unsymmetrical network structure of magnesium oxide polyhedrons, which is deemed to destroy the silica network structure. We produced glass with extremely rare impurities by melting forsterite while floating it with inert gas and sound waves and then quenching it while holding it in an approximate microgravity condition equivalent to space. Development of a new optical fiber and improvement and cost reduction of operating equipment, such as operation laser, because high-purity glass can be produced using materials, which has been deemed to be appropriate.
Kohara, Shinji*; Suzuya, Kentaro; Takeuchi, Ken*
Nihon Maikurogurabiti Oyo Gakkai-Shi, 22(2), p.100 - 104, 2005/04
Forsterite MgSiO exhibits an orthorhombic structure consisted of two kinds of MgO
octahedra. Given only 33.3 mol% of SiO in the material, the SiO tetrahedra are isolated within the framework, sharing the O-O bonds with the common edges of the MgO octahedra. If forsterite can be vitrified, an interesting question concerning the glass structure arises because there is insufficient glass forming SiO to establish the corner-sharing SiO tetrahedral network needed in conventional silicate glasses. A bulk MgSiO glass was synthesized using an aero-acoustic levitation technique and to determine the short- to intermediate-range structure by a combined high-energy X-ray and neutron diffraction and reverse Monte Carlo computer simulation. Interestingly, we found that the role of network former is largely taken on by corner- and edge-sharing ionic magnesium species that adopt 4-, 5- and 6-coordination with oxygen.
SiOWeber, 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.
