Analysis of the volume dependence of Grüneisen parameter and melting of the hcp iron
Equations for the volume dependence of Grüneisen parameter consistent with the thermodynamic constraints at extreme compression (Stacey F D, Davis P M, Phys. Earth Planet. Inter. 142 (2004) 137) have been used to determine pressure dependence of melting temperature for hcp iron with the help of the Lindemann-Gilvarry formulation. It has been discussed that the formula for the volume dependence of Grüneisen parameter used by Anderson et al. ( J. Phys. Chem. Solids 64 (2003) 2125) is not consistent with the extreme compression behaviour. Also the pressure-volume laboratory data for hcp iron taken by them are subject to considerably large errors arising from the pressure scale calibrations. In the present study we use sufficiently accurate seismic pressure-volume data along with a physically acceptable approach for determining volume dependence of Grüneisen parameter. The results obtained for the melting temperatures at different pressures for hcp iron are in good agreement with other investigations.
Keywords: Grüneisen parameter, high pressure, thermodynamic properties. hcp iron.