Structural behavior of nano iron hydroxide at the Earth surface

2016 Fiscal Year Final Research Report

• Project/Area Number: 26400511
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Petrology/Mineralogy/Economic geology
• Research Institution: University of Tsukuba
• Principal Investigator: KYONO Atsushi 筑波大学, 生命環境系, 講師 (40375431)
• Project Period (FY): 2014-04-01 – 2017-03-31
• Keywords: ナノ水酸化鉄 / フェリハイドライト / ヘマタイト / ラマン散乱 / X線散乱 / 高圧

Outline of Final Research Achievements

In the Raman spectra of both 2-line ferrihydrite and 6-line ferrihydrite samples, a weak band was observed around 600-700 cm-1 with very little pressure dependence. No clear spectra from Fe hydroxides or Fe oxides were detected in the study. The XRD pattern of 2-line ferrihydrite gradually changed with pressure. With increasing pressure, distinct three peaks were observed at 9.2 GPa. These peaks are consistent with (012), (104), (113) peaks of hematite. This result suggests that 2-line ferrihydrite transforms to hematite under high pressure condition. The phase transition from ferrihydrite to hematite can be attributable to increase of coordination number with compression. This study showed high pressure phase transition in 2-line ferrihydrite at 9.2 GPa. It may be a clue to unveil the relationship between structural transformation and dehydration in ferrihydrite.

Free Research Field

鉱物学