The study of binary ionic liquids and, as their prototypes, molten alkali halides, has a long tradition in theory, experiment as well as simulation. According to Fick's law the driving force for diffusion is a concentration gradient and can be described by a Lorentzian line with k-dependent line width which is proportional to the wave vector squared. However, detailed investigations on monatomic liquids already demonstrated that there exist deviations for the diffusion process on atomic length scales.Here we want to demonstrate that the same mechanism apply for a binary melt.