中国科学院地球化学研究所机构知识库

Synchrotron-based in situ angle-dispersive X-ray diffraction experiments were conducted on a natural uvite-dominated tourmaline sample by using an external-heating diamond anvil cell at simultaneously high pressures and temperatures up to 18 GPa and 723 K, respectively. The angle-dispersive X-ray diffraction data reveal no indication of a structural phase transition over the P-T range of the current experiment in this study. The pressure-volume-temperature data were fitted by the high-temperature Birch-Murnaghan equation of state. Isothermal bulk modulus of K-0 = 96.6 (9) GPa, pressure derivative of the bulk modulus of K-0' = 12.5 (4), thermal expansion coefficient of alpha(0) = 4.39 (27) x 10(-5) K-1 and temperature derivative of the bulk modulus (partial derivative K/partial derivative T)(P) = -0.009 (6) GPa K-1 were obtained. The axial thermoelastic properties were also obtained with K-a0 = 139 (2) GPa, K-a0' = 11.5 (7) and alpha(a0) = 1.00 (11) x 10(-5) K-1 for the a-axis, and K-c0 = 59 (1) GPa, K-c0' = 11.4 (5) and alpha(c0) = 2.41 (24) x 10(-5) K-1 for the c-axis. Both of axial compression and thermal expansion exhibit large anisotropic behavior. Thermoelastic parameters of tourmaline in this study were also compared with that of the other two ring silicates of beryl and cordierite.