X-ray diffraction and molecular dynamics simulation studies of molten uranium chloride

The structure of molten UCl3 at 1200 K was studied by high-temperature X-ray diffraction and molecular dynamics simulation. The XRD data was reproduced by the simulation with a polarizable ionic model. The nearest U3+–Cl− distance was 2.85 Å with coordination number 8.0, implying that the 8-fold structure (UCl8)5− is predominant in the melt – in contradiction to earlier suggestions of octahedral coordination. The potential model, which had been optimized by comparison with the structural data, was also found to reproduce the experimental information on transport properties like the diffusion coefficient, electrical conductivity and shear viscosity.