First-principles electronic structure calculations were used to screen 9 elements for their potential to retard O diffusion through polycrystalline films. It was found that O diffused preferentially as an interstitial along Pt grain boundaries. The calculated barriers were consistent with experimental estimates. It was found that Be controlled O diffusion through polycrystalline Pt. The Be segregated to Pt grain boundaries at interstitial and substitutional sites. The interstitial Be was slightly less mobile than O, and it repelled O; thus stuffing the grain boundaries. The substitutional Be had a high diffusion barrier and formed strong bonds with O; thus trapping O in the grain boundaries. Experiment confirmed the theoretical predictions.

Reduced Oxygen Diffusion through Beryllium-Doped Platinum Electrodes. R.Stumpf, C.L.Liu, C.Tracy: Applied Physics Letters, 1999, 75[10], 1389-91