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Journal Articles

Structure of Mg $_{2}$ SiO $_{4}$ glass made by a method for containerless supercooled-liquid-phase processing at high temperatures

Kohara, Shinji*; Suzuya, Kentaro; Takeuchi, Ken*

Mirai Zairyo, 5(4), p.28 - 33, 2005/04

http://ci.nii.ac.jp/naid/40006719359

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.

Journal Articles

Unusual structure in vitreous forsterite synthesized by an aero-acoustic levitation technique

Kohara, Shinji*; Suzuya, Kentaro; Takeuchi, Ken*

Nihon Maikurogurabiti Oyo Gakkai-Shi, 22(2), p.100 - 104, 2005/04

Forsterite Mg $_{2}$ SiO $_{4}$ exhibits an orthorhombic structure consisted of two kinds of MgO $_{6}$ octahedra. Given only 33.3 mol% of SiO $_{2}$ in the material, the SiO $_{4}$ tetrahedra are isolated within the framework, sharing the O-O bonds with the common edges of the MgO $_{6}$ octahedra. If forsterite can be vitrified, an interesting question concerning the glass structure arises because there is insufficient glass forming SiO $_{2}$ to establish the corner-sharing SiO $_{4}$ tetrahedral network needed in conventional silicate glasses. A bulk Mg $_{2}$ SiO $_{4}$ 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.