Investigation of the High-Pressure Behaviors of Amblygonite by Single-Crystal X-ray Diffraction, Raman Spectroscopy, and DFT Calculations

Abstract

In the present study, we extensively explored the high-pressure behaviors and vibrational properties of amblygonite LiAlPO4F with elevated pressures up to 34.3 GPa based on single-crystal X-ray diffraction measurements, Raman spectroscopy, and DFT calculations. The compressibility and elastic properties of amblygonite were determined first. Specifically, the obtained isothermal bulk modulus of LiAlPO4F is 128(4) GPa and the triclinic phase exhibited anisotropic compression with axial compressibility βc > βa > βb with a ratio of 1.11:1.00:1.20. The Raman spectra showed no indication of phase transformation and were used to obtained mode Grüneisen parameters. The average Grüneisen parameter for PO4 tetrahedral sites was smaller than for the LiO4F sites. Our results provide new insights into the phase stability and elastic properties of lithium-fluorite granites at extreme conditions.

Keywords

• amblygonite
• synchrotron single-crystal X-ray diffraction
• compressibility
• Raman spectroscopy
• lithium-fluorite granites