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Calibration of zircon as a Raman spectroscopic pressure sensor to high temperatures and application to water-silicate melt systems.
- Source :
- American Mineralogist; 2013, Vol. 98 Issue 4, p643-650, 8p
- Publication Year :
- 2013
-
Abstract
- The shifts in wavenumber of the v<subscript>3</subscript>(SiO<subscript>4</subscript>) (~1008 cm<superscript>-1</superscript>) Raman band of fully crystalline synthetic zircon with changing pressure (P) and temperature (T) were calibrated for application as a Raman spectroscopic pressure sensor in optical cells to about 1000 °C and 10 GPa. The relationship between wavenumber (v) of this band and T from 22 to 950 °C is described by the equation v (cm<superscript>-1</superscript>) = 7.54⋅10<superscript>-9</superscript>⋅T³ - 1.61⋅10<superscript>-5</superscript>⋅T² - 2.89⋅10<superscript>-2</superscript>⋅T + 1008.9, where T is given in °C. The pressure dependence is nearly linear over the studied range in P. At ~25 °C, the ∂v/∂P slope to 6.6 GPa is 5.69 cm<superscript>-1</superscript>/GPa, and that to 2 GPa is 5.77 cm<superscript>-1</superscript>/GPa. The ∂v/∂P slope does not significantly change with temperature, as determined from experiments conducted along isotherms up to 700 °C. Therefore, this pressure sensor has the advantage that a constant ∂v/∂P slope of 5.8 ± 0.1 cm<superscript>-5</superscript>/GPa can be applied in experiments to pressures of at least about 6.6 GPa without introducing a significant error. The pressure sensor was tested to determine isochores in experiments with H<subscript>2</subscript>O+Na<subscript>2</subscript>Si<subscript>2</subscript>O<subscript>2</subscript> and H<subscript>2</subscript>O+NaAlSi<subscript>3</subscript>O<subscript>8</subscript> fluids to 803 °C and 1.65 GPa. These pressures were compared to pressures calculated from the equation of state (EoS) of H<subscript>2</subscript>O based on the measured vapor dissolution or ice melting temperature for the same experiment. Pressures determined from the zircon sensor in runs in which NaAlSi<subscript>3</subscript>O<subscript>8</subscript> melt dissolved in aqueous fluid were close to or lower than the pressure calculated from the EoS of H<subscript>2</subscript>O using the vapor dissolution or ice melting temperature. In experiments with H<subscript>2</subscript>O+Na<subscript>2</subscript>O+SiO<subscript>2</subscript> fluids, however, the pressure obtained from the Raman spectrum of zircon was often significantly higher than that estimated from the EoS of H<subscript>2</subscript>O. This suggests that the pressures along some critical curves of water-silicate melt pseudobinary systems should be revised.v [ABSTRACT FROM AUTHOR]
- Subjects :
- CALIBRATION
PHYSICAL measurements
ZIRCON
GEMS & precious stones
SPECTRUM analysis
Subjects
Details
- Language :
- English
- ISSN :
- 0003004X
- Volume :
- 98
- Issue :
- 4
- Database :
- Complementary Index
- Journal :
- American Mineralogist
- Publication Type :
- Academic Journal
- Accession number :
- 89132500
- Full Text :
- https://doi.org/10.2138/am.2013.4143