COMPRES Project: Pressure Calibration at High Temperature

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COMPRES Project Pressure Calibration at High
Temperature
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Goal of the Program

• to examine the existing pressure scales at high
  temperature and to quantitatively determine the
  relative differences among the different pressure
  scales.

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How to implement the goal

• Evaluate existing pressure scales by in situ
  X-ray diffraction measurements in both
  multi-anvil apparatus and diamond-anvil cell
  (DAC)
• Pressure standards
• MgO, Au, Pt, NaCl, Ne, etc.
• Pressure and temperature ranges
• 28GPa-2300K in multi-anvil
• 100GPa-1000K in DAC

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Experimental Techniques

• High-temperature diamond-anvil cell (DAC)

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Experimental Techniques

• Multianvil apparatus

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Comparison of various pressure scales--Large
variations!
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Finished Project (1)
We established the thermal EOS of MgO, Au, and Pt
that predict consistent pressures. The
recommended model parameters are listed in Table
1 Fei et al., 2004a.
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Au and MgO scales
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Au and Pt scales
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Finished Project (2)
We determined phase boundaries in systems
Mg2SiO4, Mg3Al2Si3O12, and MgSiO3, using the
recommended MgO scale, which can be used as
fix-points in multi-anvil pressure calibration
Fei et al., 2004b.
Recommended values PyropePerovskiteCorundum P(
GPa) 28.58 - 0.0014T(C), RingwooditePerovski
tePericlase P(GPa) 25.12 - 0.0013T(C),
AkimotoitePerovskite P(GPa) 27.27 -
0.0031T(C)
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On-going Project
Establish NaCl(B2) and Ne pressure scales because
they are extensively used as pressure media
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On-going Project (1)
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On-going Project (2)
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Future Project

• Establish a spectroscopically-based scale
• Raman shift of 13C diamond and cubic BN as a
  function of pressure and temperature