Li+ hydration in concentrated aqueous solution

Neutron diffraction experiments were carried out on aqueous solutions of lithium chloride in heavy water at three concentrations-14, 3.6 and 1 molal. The first-order isotopic difference method was applied to the lithium ions, and structural results were obtained for the Li+ hydration: the Li-O and Li-D near-neighbour distances in the first hydration shell remain the same at 1.95(3) and 2.5(5) Angstrom over the concentration range studied. However, there is an increase in coordination number from 3.2 at 14 molal to approximate to 6.5 at 1 molal. There is also evidence for a relatively weak second hydration shell, which becomes displaced to larger distances at lower concentrations.