Abstract
We describe the experimental method and some of the results of our recent structural studies for expanded fluids. The energy-dispersive X-ray diffraction measurements for fluid Hg have been carried out for the first time in the density range from 13.55 to 8.78 g/cm3 including the metal-nonmetal transition region. It was found that the volume expansion of liquid Hg in the metallic region, to the reduced density of about 10 g/cm3, is not accompanied by a uniform increase of interatomic distance r1 but mainly caused by a decrease of coordination number N1. When the transition region is approached the decrease of N1 becomes rather small and rl starts to elongate.
