Aluminum as a pressure-transmitting medium cum pressure standard for x-ray diffraction experiments to 200 GPa with diamond anvil cells

The compressive strength of 99.999% pure aluminum as a function of pressure to 215 GPa has been determined from the linewidth analysis of high-pressure x-ray diffraction patterns recorded with beveled-diamond anvil cell. The strength is found to increase linearly from 0.3(1) GPa at zero pressure to 5.0(2) GPa at 200 GPa. The data to 55 GPa with flat anvil diamond cell suggest that the strength of 99.999% pure aluminum increases from 0.21(8) GPa at zero pressure to 1.1(1) GPa at 55 GPa and the extrapolated strength at 200 GPa is 3.3(4). Significantly larger strength obtained with beveled-diamond anvil cell most likely arises due to larger radial stress gradients than in the case of flat anvils. The strength of aluminum is compared with those of argon to 50 GPa and of helium to 70 GPa. The use of face-centered cubic phase of aluminum in the dual role of a pressure standard and solid pressure-transmitting medium to 200 GPa is discussed. (c) 2007 American Institute of Physics.