Behaviour of Grüneisen Parameter at High Pressure and Temperature Inferred from Shock Compression Data

A new method is proposed to calculate the Grüneisen parameter directly from the experimental Hugoniot data, without any assumption on the lattice vibrational mode of the material being studied. Compared with the results calculated by the methods proposed previously, the values of the Grüneisen parameter calculated have three distinguishable features that support the rationality of the method. A new phenomenon that the lattice vibrational mode changes with thermodynamic state of the solid has been first observed from the calculated results, which implies that the material parameter g, characterizing the lattice vibrational mode, is material dependent rather than a material constant.