Equation of state and compressibility of phlogopite by in-situ high-pressure X-ray powder diffraction

The elastic properties of a natural phlogopite have been studied by in-situ high-pressure X-ray powder diffraction experiments on the ID9 beamline at the ESRF, at room temperature. Several EoS models (Birch-Murnaghan, Vinet, Poirier-Tarantola) have been fitted to the experimental P-V data and the results obtained are presented and discussed. The third-order Birch-Murnaghan EoS, assuming V-0 fixed at its experimental value, yields K-0=49.7(+/-0.5) GPa, K-0'=8.59(+/-0.19), K-0'=-0.5953 GPa(-1) (implied value). The axial compressibilities at room conditions, determined by the third-order Birch-Mumaghan EoS, result in beta(a0)(EoS)=3.48(5), beta(b0)(EoS)=3.2(1), beta(c0)(EoS)=13.2(1) 10(-3) GPa(-1). Equilibrium thermodynamic calculations have been carried out to show how the new elastic parameters here reported affect the stability field of phlogopite.