An investigation was made, of the grain-boundary penetration of K+ ions, by using X-ray diffraction and microhardness measurements. The activation energy for penetration was found to be essentially independent of the boundary misorientation angle. For misorientation angles of between 12 and 14º, and at 200 to 650C, the data could be described by:

D (cm2/s) = 8 x 10-9 exp[-0.62(eV)/kT]

For misorientation angles of between 1 and 2º, and at 200 to 650C, the data could be described by:

D (cm2/s) = 4 x 10-8 exp[-0.62(eV)/kT]

Y.E.Geguzin, E.R.Dobrovinskaya, I.E.Lev, M.D.Melamud: Ukrayinskyi Fizychnyi Zhurnal, 1968, 13[12], 1972-6