Methods were described which permitted the determination of diffusion coefficients and diffusivity-solubility products. The methods were applied to the Nb-O system at 600 to 1100C, and led to the expression:

D (cm2/s) = 1.7 x 10-2 exp[-25.7(kcal/mol)/RT]

A comparison with internal friction data indicated that O occupied octahedral sites in the body-centered cubic lattice.

R.Kirchheim: Acta Metallurgica, 1979, 27[5], 869-78