Using atomic scale X-ray photon correlation spectroscopy to study atomic diffusion in alkali borate glasses

Autoren:Tietz, Christoph; Holzweber, Katharina; Legenstein, Michael; Ross, Manuel; Stana, Markus; Sepiol, Bogdan
Abstrakt:Understanding of the structure and dynamics of glasses is still in the beginning and especially the mechanisms of diffusion of glasses on the atomic level are far from being understood. Recent diffusion studies of solids focused on macroscopic methods like tracer diffusion. With the advent of atomic scale X-ray correlation spectroscopy (aXPCS) a technique able to provide the temporal and spatial resolution required for diffusion studies on the atomic scale in solids holding well for crystals and glasses.Alkali borate glasses belong to the better understood glasses in terms of the structure and due to their interesting properties as fast ion conductors an interesting candidate for diffusion studies. Diffusion experiments on two rubidium borate glasses with different concentrations were performed showing large discrepancies in the diffusivities and a clear dependence on the scattering angle. First promising results from fits to several jump models were obtained Supplementary total scattering experiments were performed to obtain the structure factor and the pair distribution functions. Both quantities provide information about structural correlations and are needed for comparison with computer simulations and models. Additional computer simulations can give insight into structural details otherwise not accessible.