The mobility of substitutional boron in single crystals of graphite was measured by an etch-decoration method, which makes it possible to locate individual boron atoms by electron microscopy. The mobility of boron was not very sensitive to the boron concentration, for B/C values between 10-2 and 10-8. The diffusion constants measured between 1700 and 2400C were 6320 exp(-157000/RT) for motion parallel to the layer planes and 7.1exp(-153000/RT) for motion perpendicular to the layers.

Diffusion of Boron in Graphite. Hennig, G.: The Journal of Chemical Physics, 1965, 42[4], 1167-72