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Study of themal pressure and phase transitions in H2O using optical pressure sensors in the diamond anvil cell
Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences.
2004 In: Journal of Physics: Condensed Matter, Vol. 16, S1223-S1233 p.Article in journal (Refereed) Published
Place, publisher, year, edition, pages
2004. Vol. 16, S1223-S1233 p.
URN: urn:nbn:se:uu:diva-93481OAI: oai:DiVA.org:uu-93481DiVA: diva2:166968
Available from: 2005-09-08 Created: 2005-09-08Bibliographically approved
In thesis
1. Optical and Raman Spectroscopic Studies on H2O at High Pressure
Open this publication in new window or tab >>Optical and Raman Spectroscopic Studies on H2O at High Pressure
2005 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

In this thesis, volumetric, optical and vibrational properties of H2O were studied at high pressures by combining techniques of Raman spectroscopy, interferometry and optical imaging. Pressures up to 7 GPa were generated in the diamond anvil cell (DAC), entering the stability fields of liquid water and ices VI, VII and VIII.

A new integrated system for Raman, interferometric and optical-imaging studies has been built up. Utilizing the interferometric patterns formed between closely-spaced diamond anvils, the system allowed the complete monitoring and control of pVT-conditions of studied ices, as well as the determination of their dispersive properties in the visible range using the Airy equation and Cauchy formulation. This setup and technique thus represent a novel tool for the precise determination of equations of state (EOSs) of transparent materials, including fluids and low-Z materials.

Data-sets on thermal pressure were obtained from heating/cooling experiments carried out on the liquid water and used for checking the mutual consistency between published EOSs. A pVT-EOS for ice VIII and room temperature isotherms for ices VI and VII at 300 K were derived by combined methods of interferometry and imaging. While the agreement with the available EOSs of ices VII and VIII is very good, some inconsistent EOSs of ice VI were identified in the present study.

The technique of micro-Raman spectroscopy was applied for the monitoring of phase transformations, identification of various ice phases and for studying the response of vibrational symmetry modes to varying conditions. Analysis based on the combination of the pT-dependencies of the vibrational frequencies with the pVT-EOSs showed that, in the studied ices, the implicit volume-driven contributions dominate over the explicit phonon effects in the total temperature-induced changes in vibrational frequencies. The results provide valuable insight on the anharmonic effects and interactions in these molecular solids.

Place, publisher, year, edition, pages
Uppsala: Institutionen för geovetenskaper, 2005. 77 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 92
Earth sciences, H2O, diamond anvil cell, equations of state, Raman spectroscopy, interferometry, Geovetenskap
National Category
Earth and Related Environmental Sciences
urn:nbn:se:uu:diva-5934 (URN)91-554-6340-1 (ISBN)
Public defence
2005-09-30, Axel Hambergsalen (or Norrland I/II), Institutionen för geovetenskaper, Villavägen 16, Uppsala, 14:00
Available from: 2005-09-08 Created: 2005-09-08Bibliographically approved

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