Equation of state of elbaite at high pressure up to 21.1 GPa and room temperature

• Published in: Physics and chemistry of minerals 2022-07, Vol.49 (7), Article 27
• Main Authors: Chen, Wei, Huang, Shijie, Ye, Zhilin, Song, Jiamei, Zhang, Shanrong, Wu, Mengzeng, Fan, Dawei, Zhou, Wenge
• Format: Article
• Language: English
• Subjects: Anisotropy; Axial compression; Bulk modulus; Compressibility; Crystallography and Scattering Methods; Crystals; Earth and Environmental Science; Earth Sciences; Equations of state; Geochemistry; High pressure; Mineral Resources; Mineralogy; Original Paper; Phase transitions; Room temperature; Synchrotron radiation; Synchrotrons; Unit cell; X-ray diffraction
• ISSN: 0342-1791; 1432-2021
• DOI: 10.1007/s00269-022-01201-w

The equation of the state of a natural elbaite sample has been investigated at room temperature and up to 21.1 GPa for the first time using in situ synchrotron X-ray diffraction in this study. No phase transition is observed on elbaite over the experimental pressure range. The pressure–volume data were fitted by the third-order Birch-Murnaghan equation of state (EoS) with the zero-pressure unit-cell volume V 0 = 1540.7 (6) Å 3 , the zero-pressure bulk modulus K T 0 = 114.7 (7) GPa, and its pressure derivative K ' T0  = 4.2 (1), while obtained V 0 = 1540.1 (4) Å 3 and K T0  = 116.4 (4) GPa when fixed K ' T0  = 4. Furthermore, the axial compressional behavior of elbaite was also fitted with a linearized third-order Birch-Murnaghan EoS, the obtained axial moduli for a -axis and c -axis are K a0  = 201 (4) GPa and K c0  = 60 (1) GPa, respectively. The axial compressibilities of a -axis and c -axis are β a  = 1.66 × 10 –3 GPa −1 and β c  = 5.56 × 10 –3 GPa −1 with an anisotropic ratio of β a : β c  = 0.30: 1.00, which shows an intense axial compression anisotropy. The potential influencing factors on the bulk moduli and the anisotropic linear compressibilities of tourmalines were further discussed.