Pressure‐induced phase transitions of vaterite, a metastable phase of CaCO3. (10th May 2017)

• Record Type: Journal Article
• Authors: Maruyama, Koji; Kagi, Hiroyuki; Komatsu, Kazuki; Yoshino, Toru; Nakano, Satoshi
• Other Names: Korsakov Andrey V. guestEditor.; Marshall Craig Patrick guestEditor.
• Is Part Of: Journal of Raman spectroscopy. Volume 48:Number 11(2017)
• Page Start: 1449
• Page End: 1453
• Publication Date: 2017-05-10
• Subjects: vaterite -- calcite -- calcium carbonate -- phase transition -- high pressure; Raman spectroscopy -- Periodicals; 535.846
• DOI: 10.1002/jrs.5162
• Languages: English
• ISSNs: 0377-0486

Abstract

Abstract : Pressure‐induced phase transitions of vaterite, a metastable phase of CaCO3, were observed from Raman spectra and X‐ray diffraction patterns at high pressure using diamond anvil cells at room temperature. Pressure dependence of Raman peaks assignable to the symmetric stretching vibration modes of carbonate ion indicated the phase transitions of vaterite. At 4.3 GPa, vaterite (vaterite I) transformed to a high‐pressure form of vaterite (vaterite II). With increasing pressure, a part of vaterite II gradually transformed to calcite III, and the remainder of vaterite II transformed to another new phase (vaterite III). The phase transition from vaterite II to calcite III was irreversible, and calcite III back‐transformed to calcite I during decompression. Moreover, at the pressures higher than 13.1 GPa, several diffraction spots were observed on an imaging plate, indicating another phase transition from vaterite III to a phase having coarse grains (vaterite IV). Our results indicate that vaterite undergoes more complex phase transitions at high pressure than other polymorphs of calcium carbonate, calcite, and aragonite. These phase transitions of vaterite will open a window to understanding phase transitions of metastable minerals at high pressure. Copyright © 2017 John Wiley & Sons, Ltd. Abstract : Pressure‐induced phase transitions of vaterite, a metastable phase of CaCO3, were observed from Raman spectra and X‐ray diffraction patterns at room temperature. At 4.3 GPa, vaterite transformed to vaterite II. With increasing pressure, a part of vaterite II transformed to calcite III, and the remainder of vaterite II transformed to vaterite III. The phase transition from vaterite II to calcite III was irreversible. At pressures higher than 13.1 GPa, another phase transition from vaterite III to vaterite IV was found.