Structure of liquid lithium

Abstract

Neutron diffraction experiments, made at a steady-state reactor source, were used to study the structure of liquid7Li at temperaturesof 197, 452 and 595 °C. A careful data analysis procedure was undertaken in which specific issues taken intoaccount include (i) the influence of Brillouin modes on the measured diffractionpattern at small scattering vectors, (ii) inelasticity corrections that are significantfor light atom systems, such as lithium, and (iii) the effects caused by thediffractometer resolution function. Data sets taken for the same liquid temperatureusing different incident neutron energies yield ion–ion partial structure factors,SII(k), that are in agreement within the statistical errors. TheSII(k) are compared with previous experimental results and with the results obtainedfrom liquid state theory and molecular dynamics methods made using severaldifferent local pseudopotentials. Finally, the valence electron form factor,ρ(k), is estimatedby combining SII(k) with x-ray diffraction data and the ion–valence electron partial structure factor,SIe(k), is calculatedby combining SII(k) with the ρ(k) obtained from both experiment and theory. The results show that the extraction ofρ(k) and SIe(k) by a combination of neutron and x-ray diffraction methods is feasible in practice, butdemonstrates a need for new x-ray diffraction experiments on liquid lithium.