High-pressure behaviour and equation of state of calcite, CaCO₃

Abstract

The high-pressure response of the cell parameters of calcite, CaCO₃, has been investigated by single crystal X-ray diffraction. The unit cell parameters have been refined from 0 to 1.435 GPa, and the linear and volume compressibilities have been measured as β _a =2.62(2) × 10⁻³ GPa⁻¹,β _c =7.94(7) × 10⁻³ GPa⁻¹, β _v =13.12 × 10⁻³ GPa⁻¹. The bulk modulus has been obtained from a fit to the Birch-Murnaghan equation of state, giving K ₀=73.46 ± 0.27 GPa and V ₀=367.789 ± 0.004 ų with K′=4. Combined with earlier data for magnesite, ankerite and dolomite, these data suggest that K ₀ V ₀ is a constant for the Ca-Mg rhombohedral carbonates.