11:45 〜 12:00
[SGC52-11] In situ optical study of H2O-CO2-CO system at high pressures
キーワード：Externally heated diamond anvil cell, Raman spectroscopy, C-O-H fluid
Externally heated diamond anvil cell (DAC) technique provides optical access to the sample, homogeneously heated to high temperatures, and is widely used for in situ observations and spectroscopic measurements. Nevertheless, the pressure range achievable with the conventional externally heated hydrothermal DAC is limited by low resistance of diamond anvils to thermal stress at high temperatures. In this study we used a modified external heating system combined with the lever type DAC (Whale cell) in order to reach simultaneous high temperatures and high pressures for in situ measurements.
Visual observations and Raman spectroscopy were carried out for C2H2O4 composition in the temperature range to 720 degree C and pressure range to 6.4 GPa. Above 105 degree C and 1 GPa a dissociation of starting material with the formation of CO2 solid, H2O and CO fluid phases was observed. At temperatures above 377 degree C and pressures above 2 GPa a polycrystalline phase was stable, which transformed to a solid carbon phase above 565 degree C and 5.5 GPa. Raman spectra of the solid carbon phase contain two broad peaks, consistent with the D breathing mode and G bond-stretching mode of C atoms. Therefore, solid phases are stable in this system in the broad region of temperatures and pressures.
Obtained results have interesting implications for transportation mechanism of water and CO2 into the Earth’s interior in cold subduction zones.
Visual observations and Raman spectroscopy were carried out for C2H2O4 composition in the temperature range to 720 degree C and pressure range to 6.4 GPa. Above 105 degree C and 1 GPa a dissociation of starting material with the formation of CO2 solid, H2O and CO fluid phases was observed. At temperatures above 377 degree C and pressures above 2 GPa a polycrystalline phase was stable, which transformed to a solid carbon phase above 565 degree C and 5.5 GPa. Raman spectra of the solid carbon phase contain two broad peaks, consistent with the D breathing mode and G bond-stretching mode of C atoms. Therefore, solid phases are stable in this system in the broad region of temperatures and pressures.
Obtained results have interesting implications for transportation mechanism of water and CO2 into the Earth’s interior in cold subduction zones.