Structural transition in liquid iron around the triple point

Occurrence of solid/solid phase transitions often affects the melting line and the properties of the corresponding liquid. In the case of Fe, the fcc-hcp-liquid triple point, around 100 GPa and 3500 K, is related to a change in the slope of the melting curve. This argues for possible changes in the physical properties of liquid Fe. Data collected in a previous XRD experiment intriguingly suggest a change in the compressibility of liquid Fe around the triple point. In order to confirm these preliminary observations, and relate this macroscopic behaviour to possible changes in the local atomic arrangement from a fcc-like to an hcp-like structure, we would need further data, in particular at P-T conditions above 100 GPa. We propose to probe the X-ray diffuse scattering signal of liquid Fe as a function of pressure above the triple point, so to confirm changes in the compressibility and further investigate the possibility of this to be due to modification of the local structure.