We report neutron diffraction measurements for two Ne-Xe mixtures at T = 275 K and P =26 MPa, having a Xe molar fraction of 0.81 and 0.45, respectively. These thermodynamic points are chosen to be in the single phase region, close to the gas-gas demixing surface. Total structure factors and neutron weighted pair distribution functions have been extracted. Partial pair distribution functions gij(r) have been calculated by means of molecular dynamics simulation using Lennard-Jones interaction potentials and the Lorentz-Berthelot mixing rules, obtaining a good agreement with the experimental data. These partial pair distribution functions have been analyzed in terms of density expansion and also compared with those derived in a previous experiment on a He-Xe mixture. The main difference found between the structural properties of the two mixtures is that, in the Ne containing mixture, a definitely larger fraction of atoms of the lighter species occupies the Xe-Xe first neighbor shell. The model already used in interpreting the thermodynamic behavior of the He-Xe mixture in terms of microscopic properties suggests that this structural difference is related to the different behavior of the pressure-temperature projection of the critical line in the two mixtures.
Nardone, M., Ricci, F.P., Filabozzi, A., & Postorino, P. (1996). Structure of the Ne-Xe mixture near the 26-MPa demixing curve at T=275 K. PHYSICAL REVIEW E, 54(6), 6381-6386 [10.1103/PhysRevE.54.6381].