Gruneisen parameter of epsilon-iron up to 300 GPa from in-situ X-ray study

We show that high-quality powder X-ray diffraction data, collected in diamo nd anvil cells, provide sufficient information for Rietveld refinement and determination of temperature factors. For the first time using a new method based on combination of thermal equation of state and measured mean-square atomic vibrations of high-pressure epsilon-Fe phase, we determine Debye te mperatures at pressure up to 300 GPa and temperature over 1000 K. We found that the Gruneisen parameter of epsilon-iron could be described by Anderson 's (1967) equation with parameters gamma(0) = 1.78(6), q = 0.69(10) with fi xed V-0 = 6.73 cm(3)/mol.