The serial sectioning technique was used to study the self-diffusion of Br in single crystals (figure 3). The self-diffusion coefficient of Br was 2 or 3 orders of magnitude lower than those of Ag and Na. A study of interdiffusion in this system (using sectioning and electron microprobe micro-analysis) also showed that the interdiffusion coefficient at 400C was almost the same as the self-diffusivity of Br over the entire composition range.

Self-Diffusion and Interdiffusion in the AgBr-NaBr System. T.Tsuji: Journal of Solid State Chemistry, 1970, 2[4], 563-9