Quantitative measurements of pressure gradients for the pyrophyllite and magnesium oxide pressure-transmitting mediums to 8 GPa in a large-volume cubic cell

Abstract

Quantitative measurements of pressure gradients have been made in the pyrophyllite and magnesium oxide (MgO) pressure-transmitting mediums using large-volume cubic apparatus. The relationships of pressure gradients along the axis of symmetry of the pyrophyllite and MgO cubes versus corresponding cell pressures have been established at room temperature. Our experimental results indicated that the pressure gradients increase as the cell pressure increases and that the pressure gradient in the MgO pressure-transmitting medium is about twice as high as that in the pyrophyllite pressure-transmitting medium at the same cell pressure. When the cell pressure reaches 5.5 GPa, the pressure gradient along the axis of symmetry of the pyrophyllite cube is about 50 MPa/mm. When the cell pressure reaches 7.7 GPa, the pressure gradient along the axis of symmetry of the MgO cube is about 140 MPa/mm. The experimental data obtained in the present work not only adapt to the cubic apparatus but also provide reference for the tetrahedral press and the double-stage multi-anvil apparatus (the octahedral compression).

Keywords:

• quantitative measurements
• pressure gradients
• large-volume cubic apparatus
• pressure-transmitting medium

Acknowledgements

We are grateful to Yanbin Wang and an anonymous reviewer for their suggestions and comments. This work was supported by National Natural Science Foundation of China (Grant No. 11027405), National Natural Science Foundation of China – NSAF (Grant No. 10976018) and the China 973 Program (Grant No. 2011CB808200).