X-ray diffraction measurements for expanded fluid mercury using synchrotron radiation: from the liquid to dense vapor

Abstract X-ray diffraction measurements for expanded fluid mercury have been carried out in a wide density region from the liquid to dense vapour region using synchrotron radiation at SPring-8. We have developed a new high-pressure vessel with seven windows to collect the scattered X-rays for energy-dispersive X-ray diffraction measurements under high temperature and high pressure, and present the new data. It was found that the reliability of the structure factors, S(k), and the accuracy of the pair distribution functions, g(r), are much better. Reliable relations of the coordination number and the correlation distance with the density of fluid Hg were obtained. Structural changes with decreasing density are discussed in relation to the metal–non-metal transition in fluid Hg based on the new results.