Compressibility and expansivity of anglesite (PbSO₄) using in situ synchrotron X-ray diffraction at high-pressure and high-temperature conditions

Abstract

The compressibility and expansivity of anglesite (PbSO₄) have been measured at high pressure up to 21.6 GPa and high temperature up to 700 K using in situ angle-dispersive X-ray diffraction and diamond anvil cell. The third-order Birch–Murnaghan equation of state (III-BM-EoS) was used to analyze the pressure–volume (P–V) data of PbSO₄. We obtained the bulk modulus K₀ = 59(1) GPa, and its pressure derivative $K_{0}^{'}$ = 5.3(4), respectively. Using Holland–Powell thermal EoS to fit the temperature–volume (T–V) data, the thermal expansion coefficient α₀ = 4.59(2) × 10^− 5 K^− 1 for PbSO₄ was also derived. Simultaneously, the ambient-pressure axial compressibilities (β_a0 = 1.79(4) × 10^− 3 GPa^− 1, β_b0 = 1.75(5) × 10^− 3 GPa^− 1, β_c0 = 2.12(4) × 10^− 3 GPa^− 1) and axial thermal expansivities (α_a0 = 1.23(4) × 10^− 5 K^− 1, α_b0 = 1.93(2) × 10^− 5 K^− 1, and α_c0 = 1.43(1) × 10^− 5 K^− 1) along a-axis, b-axis and c-axis were derived at 300 K, respectively. Furthermore, the potential influencing factors (e.g., the effective size of M²⁺ cation, polarizability and electronegativity) on the bulk moduli of barite-type (belonging to Pbnm space group) sulfates (anglesite, barite, and celestine) were discussed. We found that the polarizability might be the most important factor. Finally, the anisotropic linear compressibility and thermal expansivity in barite-type sulfates were also discussed, respectively.