Phase diagram and melting curve of iron obtained using the data of static and shock-wave measurements

Interest shown by geophysicists in the Earth's core has stimulated numerous investigations of the phase diagram of iron and its melting curve in the pressure range up to several megabar and temperature range up to several thousand degrees. The development of new investigation methods involving the use of laser heating and in situ diagnostics with the aid of X-radiation has promoted the studies into the solid phase structure under conditions of static compression in diamond anvils. The results obtained by different research teams, though differing in details, have made it possible to determine the position of the phase boundaries in the phase diagram and make estimates of the density dependence of the Grueneisen coefficient for the main phases of iron, which correlate in varying degrees with the data on the melting curve. In this paper, shock-wave and static data for iron available in the literature are analyzed, as well as the parameters of the equation of state for the $\gamma$ and $\varepsilon$ phases obtained using the experimental data on isentropic expansion from the state of shock compression.