Physics and Chemistry of Minerals

, Volume 29, Issue 3, pp 181–187 | Cite as

Raman spectra of hydrous γ -Mg2SiO4 at various pressures and temperatures

  • L. Liu
  • C.-C. Lin
  • T. P. Mernagh
  • T. Inoue
ORIGINAL PAPER

Abstract

 One well-defined OH Raman band at 3651 ± 1 cm−1 and one weak feature near 3700 ± 5 cm−1 are recognized for the hydrous γ-phase of Mg2SiO4. Like the hydrous β-phase, the H2O content in the γ-phase shifts most of the corresponding silicate modes towards lower frequencies. Variations in Raman spectra of the hydrous γ-phase were investigated up to about 200 kbar at room temperature and in the range 81–873 K at atmospheric pressure. Unlike the anhydrous γ-phase, which remains intact up to at least 873 K, the hydrous γ-phase sometimes converts to a defective forsterite structure above 800 K. Although the hydrous γ-phase remains intact up to at least 800 K, Raman signals of the OH bands disappear completely above 423 K. The Raman frequency of the well-defined OH band decreases linearly with increasing temperature between 81 and 423 K. In the region of the silicate vibrations, the Raman frequencies of the two most intense bands increase nonlinearly with increasing pressure, and decrease with increasing temperature. The frequencies for all other weak bands, however, decreased linearly with increasing temperature. The latter most likely reflects the larger scatter of the data for the weak bands.

Keywords Hydrous γ-Mg2SiO4 Raman spectrum Pressure dependence Temperature dependence 

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Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • L. Liu
    • 1
  • C.-C. Lin
    • 1
  • T. P. Mernagh
    • 2
  • T. Inoue
    • 3
  1. 1.Institute of Earth Sciences, Academia Sinica, Nankang, Taipei, Taiwan, ROC e-mail: lliu@earth.sinica.edu.twCN
  2. 2.Australian Geological Survey Organisation, Canberra, ACT, 2601 AustraliaAU
  3. 3.Department of Earth Sciences, Ehime University, Matsuyama 790, JapanJP

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