Compression of lithium fluoride to 92 GPa

Abstract

The equation of state and compression behavior of lithium fluoride, LiF, have been determined to 92 GPa by X-ray diffraction in a diamond anvil cell. A neon pressure-transmitting medium was used to minimize the effect of differential stress on the sample. Consistent results using multiple pressure standards were obtained. By fitting the pressure–volume data to a Birch–Murnaghan equation of state, the isothermal bulk modulus and its corresponding pressure derivative at zero pressure were determined to be K0=70.1±0.7 GPa, and K′0=4.3±0.1. If the bulk modulus is fixed at 66.2 GPa, a value well constrained by independent elasticity measurements, we obtain K′0=4.6±0.1. The bulk modulus and its pressure derivative obtained from this work resolve the large discrepancy in previously reported values of K0 and K′0 for this material. Consequently, the equation of state of LiF is now sufficiently well constrained to allow its use as a pressure calibrant in high pressure experiments.