Equations of state of six metals above94GPa

Abstract

Compression versus pressure at ambient temperature has been measured for tantalum, gold, and platinum to $94\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ and for aluminum, copper, and tungsten to $153\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, in a diamond anvil cell. Standard synchrotron x-ray diffraction accuracy in the volume determination could be achieved to the maximum pressure. The current data set is used to recalibrate the static pressure scale based on the ruby luminescence, confirming recent suggestions of an underestimation of pressure. Using an updated pressure calibration, the consistency between ultrasonic, dynamic, and static measurements of the equations of state is improved for these six equations of state. This consistency allows us to test the predictive power of density functional theory, with different approximations, for equation-of-state calculations. For example, the generalized gradient approximation leads to very accurate results, except for gold, the heaviest element.