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Thermal expansion, heat capacity and Grüneisen parameter of grossular at high temperature and high pressure
Chang Su and Yonggang Liu

The thermodynamic properties of grossular garnet (Ca3Al2Si3O12) were determined as a function of pressure and temperature in this study. With a numerical iterative procedure, the unit-cell volume, adiabatic bulk modulus, thermal expansion, heat capacity, and Grüneisen parameters of grossular up to 25 GPa, 2000 K were extracted from experimental elastic wave velocities at high temperature and high-pressure conditions. The calculated unit-cell volume and adiabatic bulk modulus agree well with the previous studies. The results imply that our calculated thermal expansion, heat capacity, and Grüneisen parameters of grossular are all decrease with elevated pressure, and both thermal expansion and heat capacity show nonlinear pressure dependences. On the other hand, the Grüneisen parameter shows a linear pressure dependence. The pressure derivative of thermal expansion display a regularity increase with temperature, while the pressure derivatives of heat capacity and Grüneisen parameters display a rapid decrease at low temperature and a slow growth above ~1000 K.

Keywords: Grossular; Thermodynamic parameters; High-temperature High-pressure; Elastic wave velocity

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