The rate of Ni2+ diffusion was measured along the a- and c-axes of monocrystals at 900 to 1550C. The samples were encapsulated in polycrystalline disks during annealing in order to inhibit losses of solute or host material by vaporization. It was found that the results exhibited a small dependence upon the crystallographic direction, with equations:

D (cm2/s) = 9.89 x 10-5exp[-2.06(eV)/kT]

and

D (cm2/s) = 3.16 x 10-5exp[-2.06(eV)/kT]

for the a- and c-axis directions, respectively.

B.J.Wuensch, H.L.Tuller: Journal of the Physics and Chemistry of Solids, 1994, 55[10], 975-84