Total structure factors (Bragg, diffuse scattering) for the γ-, β- and α-phases were measured by means of powder neutron diffraction. Reverse Monte Carlo modelling of the data was used to obtain information on the distribution of mobile Cu+ ions. The reverse Monte Carlo results for the γ- and α-phases were in good agreement with molecular dynamics simulations and the Rietveld refinement of high-resolution Bragg scattering powder neutron diffraction data. They confirmed that the predominant diffusion pathway was in the <100> direction, directly between tetrahedrally coordinated Cu+ sites. The octahedral site was not occupied, but there was a very small amount of diffusion through this site, along <111> directions, at the highest temperatures. There were small differences between the reverse Monte Carlo, molecular dynamics and Rietveld refinement data for the β-phase. In all of the phases, the radial distribution functions which were obtained by experiment were significantly different to the molecular dynamics results. It was clearly shown that there was a relationship between experimental observations of a broad diffuse scattering peak, at about 1/Å in the structure factor for the β- and α-phases, and the existence of a short-distance peak, in gCuCu(r), in the reverse Monte Carlo models.

Structure and Ionic Conduction in CuI - Diffuse Neutron Scattering and RMC Modelling. A.Chahid, R.L.McGreevy: Journal of Physics - Condensed Matter, 1998, 10[12], 2597-609