No reactions observed in Xe-Fe system even at Earth core pressures

[1] The behavior of Xe-Fe system was investigated under ultra-high pressures by in situ X-ray diffraction measurements using a laser-heated diamond anvil cell. Although Xe-Fe interaction have been regarded as one of the most probable explanations for the missing Xe problem, no compounds and no detectable amounts of dissolution of xenon into crystalline hcp iron occur even above the metallization pressure of xenon up to 155 GPa and 3000 K. Furthermore, the c/a ratio of hcp xenon and iron vary in opposite ways with increasing pressure, indicating that the nature of these two metals deviates more at high pressures. These results and the fact that incorporation of nickel and light elements into iron tends to stabilize structures other than the hcp structure imply that the retention of xenon in the Earth's core is very unlikely by a solid-solution mechanism, and some other mechanism needs to be found to explain the missing xenon problem.