The diffusion of Nb in single crystals was deduced from Nb diffusion profiles at 1530 to 1723K, in air. The Arrhenius plot of the diffusion data indicated that there was a change in the diffusion mechanism at 1626K. At 1530K, the data were consistent with the chemical diffusion coefficient of Nb-doped BaTiO3. It was found that transport at 1530K, and above, occurred according to a different mechanism. Below 1481K, the process of Nb incorporation was substantially retarded.

Kinetics of Nb Incorporation into Barium Titanate. K.Kowalski, M.Ijjaali, T.Bak, B.Dupre, J.Nowotny, M.Rekas, C.C.Sorrell: Journal of the Physics and Chemistry of Solids, 2001, 62[3], 531-5