Development of density measurement at high pressure and high temperature using the x-ray absorption method combined with laser-heated diamond anvil cell.

Abstract

The densities of liquid materials at high pressures and high temperatures are important information to understand the elastic behavior of liquids at extreme conditions, which is closely related to the formation and evolution processes of the Earth and planetary interiors. The x-ray absorption method is an effective method to measure the density of non-crystalline materials at high pressures. However, the temperature condition of the x-ray absorption method using a diamond anvil cell (DAC) has been limited to 720 K to date. To significantly expand the measurable temperature condition of this method, in this study, we developed a density measurement technique using the x-ray absorption method in combination with a laser-heated DAC. The density of solid Ni was measured up to 26 GPa and 1800 K using the x-ray absorption method and evaluated by comparison with the density obtained from the x-ray diffraction. The density of solid Ni with a thickness >17 μm was determined with an accuracy of 0.01%-2.2% (0.001-0.20 g/cm3) and a precision of 0.8%-1.8% (0.07-0.16 g/cm3) in the x-ray absorption method. The density of liquid Ni was also determined to be 8.70 ± 0.15-8.98 ± 0.38 g/cm3 at 16-23 GPa and 2230-2480 K. Consequently, the temperature limit of the x-ray absorption method can be expanded from 720 to 2480 K by combining it with a laser-heated DAC in this study.