Compressibility of a natural smithsonite ZnCO₃ up to 50 GPa

Abstract

Natural smithsonite (ZnCO₃) has been investigated by synchrotron radiation X-ray diffraction and X-ray absorption spectroscopy combined with diamond anvil cells up to 50 GPa at room temperature. At ambient pressure, smithsonite adopts as calcite phase with a=4.6557(11) Å and c=15.072(12) Å. Both experimental results demonstrate that no phase transition occurs in the present examined pressure range. Isothermal pressure–volume relationship of smithsonite can be well described by the third-order Birch–Murnaghan equation of state with V₀=284.6(7) Å³, B₀=126.8(6) GPa and (fixed). The axial compressibility of smithsonite presents clear anisotropy with α_c=3.60×10⁻³ Å GPa⁻¹>α_a=1.21×10⁻³Å GPa ⁻¹. ZnCO₃-smithsonite is proposed to approach the NaCl rocksalt structure on compression.

Keywords:

• smithsonite
• compressibility
• X-ray diffraction
• X-ray absorption spectroscopy
• diamond anvil cell

Acknowledgements

The authors gratefully acknowledge Wu Ye and Zhang Qian for their assistance with XAS data collection. This work was supported by Natural Science Foundation of China (grant no. 41072027, 11079009 and U1232204).