Thin films of La on polycrystalline Mo surfaces were studied. Analysis of depth profiles at 800 to 1300K indicated that the bulk diffusivity could be described by:

D (cm2/s) = 1.9 x 10-8 exp[-1.7(eV)/kT]

while the grain boundary diffusivity could be described by:

D (cm2/s) = 1.2 x 10-6 exp[-1.07(eV)/kT]

G.S.Rao, C.V.Dharmadhikari, A.S.Nigavekar: Journal of Vacuum Science and Technology A, 1989, 7[5], 3005-12