The self-diffusion of 93Nb in Nb-doped single crystals (4.3at%Nb) was studied at high oxygen activities and 1073 to 1573K. The diffusion-induced 93Nb concentration profile was determined by using secondary ion mass spectrometry. The data could be described by:

D(m2/s) = 1.77 x 10-9exp[-197(kJ/mol)/RT]

L.R.Sheppard, A.J.Atanacio, T.Bak, J.Nowotny, M.K.Nowotny, K.E.Prince: Journal of Solid State Electrochemistry, 2009, 13[7], 1115-21