Volume 09, No.3
May issue 2004
1. SPring-8の現状／PRESENT STATUS OF SPring-8
Call for the Beam Time Application for the Public Beamlines at SPring-8
Call for the Beam Time Application for Nanotechnology Experiments
The Experiments in the 12th Research Period (2003B) at the Public Beamlines of SPring-8
2. 最近の研究から／FROM LATEST RESEARCH
愛媛大学 地球深部ダイナミクス研究センター Geodynamics Research Center, Ehime University
- Carbonates are important constituents of marine sediments and play an important role in the long-term recycling of carbon in the Earth’s deep interior via subduction of oceanic plates. We studied the stability of magnesite, the major carbonate in the mantle, by in situ X-ray diffraction measurements using a combination of laser-heated diamond anvil cell (LHDAC) and synchrotron radiation at BL10XU. We found that magnesite is stable at pressure up to ~115 GPa, at temperatures of ~ 2100 - 2200K, whereas it transforms to a new phase at higher pressures. The diffraction data of the new phase, magnesiteⅡ, are reasonably indexed on the basis of an orthorhombic system, yielding a density of 5.2 g/cm3 at 119 GPa, at room temperature. The present results suggest that magnesite and its high-pressure form are the major hosts for carbon throughout the most parts of the Earth’s lower mantle.
A Study of an Unusual Glass Prepared by the Containerless Method – Glass Formation at the Limit of Insufficient Network Formers –
（財）高輝度光科学研究センター 利用研究促進部門Ⅰ Materials Science Division, JASRI、日本原子力研究所 中性子利用研究センター Neutron Science Research Center, Japan Atomic Energy Research Institute、東京理科大学 基礎工学部 Faculty of Industrial Science and Technology, Tokyo University of Science
- 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 of which the interconnectivity is realized by sharing the 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 SiO2 to establish the needed interconnectivity. We have studied a bulk magnesium orthosilicate glass obtained by levitation melting- and-cooling. We find 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.
Study on Element-and Site-Specific Vibrational Densities of States Using Nuclear Resonant Inelastic Scattering
3. 研究会等報告／WORKSHOP AND COMMITTEE REPORT
Activities of the SPring-8 Advisory Committee and the Others in the 2003 Fiscal Year