High-temperature, high-pressure behavior of common windows and pressure calibrants: LiF and MgO

Lithium fluoride (LiF) and periclase (MgO) are used extensively as optical windows in dynamic compression experiments and also used as pressure media and thermal insulation layers in laser-heated diamond-anvil cell (LHDAC) experiments. To better understand these important high-pressure standards and ubiquitous window materials, we present their solid high-temperature equations of state as determined in a LHDAC. Transparent samples of LiF and MgO foils were coated with either Mo, Ag or Au in order to couple with the near-infrared laser for heating between ~1000-2500 K and pressures up to ~80 GPa. Finite element analysis was used to determine temperatures of the insulation layers based on the measured temperature of the metal coatings. These measurements complement already measured low-T isotherms performed with resistively-heated DACs.