The high-pressure and temperature equation of state of a majorite solid solution in the system of Mg4Si4O12-Mg3Al2Si3O12

The high-pressure and temperature equation of state of majorite solid solution, Mj(0.8)Py(0.2), was determined up to 23 GPa and 773 K with energy-dispersive synchrotron X-ray diffraction at high pressure and high temperature using the single- and double-stage configurations of the multianvil apparatuses, MAX80 and 90, The X-ray diffraction data of the majorite sample were analyzed using the WPPD (whole-powder-pattern de-composition) method to obtain the lattice parameters. A least-squares fitting using the third-order Birch-Murnaghan equation of state yields the isothermal bulk modulus, K-T0 = 156 GPa, its pressure derivative, K' = 4.4(+/- 0.3), and temperature derivative (partial derivative K-T/ partial derivative T)(p) = -1.9(+/- 0.3)x 10(-2) GPa/K, assuming that the thermal expansion coefficient is similar to that of pyrope-almandine solid solution.