2 0 0 0 OA 単結晶中性子回折による地球深部含水鉱物の結晶構造解析
- 著者
- 奥地 拓生 プレジャブ ナランゴー 富岡 尚敬
- 出版者
- 日本結晶学会
- 雑誌
- 日本結晶学会誌 (ISSN:03694585)
- 巻号頁・発行日
- vol.59, no.6, pp.309-315, 2017-12-31 (Released:2017-12-31)
- 参考文献数
- 30
- 被引用文献数
- 1
Water in the Earth has been transported from the oceans into its deep interior, where it forms hydrous deep mantle minerals. Wadsleyite [(Mg,Fe)2SiO4] has been considered as one of the most important host minerals incorporating this type of water as hydroxyl groups. To constrain the capacity of water in its structure and also to understand the effect of such water on its physical properties, it is essential to quantitatively determine the hydrogenʼs site and occupancy in the wadsleyite structure. Here we conduct a neutron time-of-flight single-crystal Laue diffraction study of it. Single crystals, which have size and quality suitable for this method, were successfully synthesized by a slow-cooling method at the relevant high pressure and temperature condition. The results unambiguously demonstrate a unique incorporation mechanism of hydrogen into the wadsleyite structure.
1 0 0 0 OA 小惑星リュウグウ粒子の衝撃圧力推定
- 著者
- 富岡 尚敬 Phase 2キュレーション高知チーム
- 出版者
- 日本結晶学会
- 雑誌
- 日本結晶学会誌 (ISSN:03694585)
- 巻号頁・発行日
- vol.65, no.4, pp.216-217, 2023-12-15 (Released:2023-12-20)
- 参考文献数
- 9
1 0 0 0 OA 衝撃変成を受けた隕石中に発見された新鉱物:秋本石
- 著者
- 富岡 尚敬
- 出版者
- 一般社団法人 日本鉱物科学会
- 雑誌
- 岩石鉱物科学 (ISSN:1345630X)
- 巻号頁・発行日
- pp.231002, (Released:2023-10-16)
Akimotoite (IMA1997-044), (Mg,Fe)SiO3, a new silicate mineral of the ilmenite group, has been discovered in the shocked Tenham chondritic meteorite. It occurs as aggregates adjacent to clinoenstatite in host-rock fragments trapped into shock-induced melt veins. Chemical analysis gives the simplified formula to be (Mg0.79Fe0.21)SiO3, the same as for clinoenstatite. Selected-area electron diffraction (SAED) patterns correspond to the synthetic (Mg,Fe)SiO3 ilmenite phase with the space group R3. The lattice parameters estimated from the SAED patterns are a = 0.478(5) nm, c = 1.36(1) nm in the hexagonal setting. The calculated density is 4.0(1) g/cm3. In a shock-induced melt vein, akimotoite and clinoenstatite are intergrown with a topotaxial relationship in which close-packed oxygen layers of both phases are preserved. This occurrence suggests that the enstatite-akimotoite transition was caused by a shear transformation mechanism without long-range atomic diffusion.
- 著者
- 富岡 尚敬
- 出版者
- 日本惑星科学会
- 雑誌
- 遊・星・人 : 日本惑星科学会誌 (ISSN:0918273X)
- 巻号頁・発行日
- vol.20, no.2, pp.154-160, 2011-06-25
- 被引用文献数
- 1
コンドライト隕石が経験した衝撃圧力は,衝撃回収実験によるケイ酸塩鉱物の変形,再結晶,溶融,相転移の組織と隕石組織との比較をもとに見積もられてきた.しかし,天然の衝突現象と室内の衝撃実験とでは,衝突体のサイズに起因する圧力タイムスケールの大きな違いという本質的問題を抱えている.最近の静的高圧実験によるケイ酸塩の相転移実験の結果は,衝撃実験に基づく従来の圧力スケールは,コンドライトが実際に経験した圧力を過剰に見積っている可能性を示唆している.