Compression of lithium fluoride to 92GPa

The equation of state and compression behavior of lithium fluoride, LiF, have been determined to 92GPa 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 K-0=70.1 +/- 0.7GPa, and K '(0)=4.3 +/- 0.1. If the bulk modulus is fixed at 66.2GPa, 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 K-0 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.