Self-diffusion studies of B in polycrystalline material were carried out, as a function of temperature, using stable 10B tracers, 11B-enriched samples and secondary ion mass spectrometry depth profiling. The diffusivities were deduced, from isotope depth profiles, at 950 to 1600C. They obeyed the relationship:

D (m2/s) = 4 x 10-12 exp[-2.2(eV)/kT]

Extrapolation of the diffusivity to the melting point (3225C) revealed a very low value of about 10-15m2/s; which reflected the covalent bonds present in the material. A possible explanation for the low values obtained for the Arrhenius parameters was diffusion via vacancies where, in addition to thermal vacancies, a substantial concentration of structural vacancies was present.

Self-Diffusion of Boron in TiB2. H.Schmidt, G.Borchardt, C.Schmalzried, R.Telle, S.Weber, H.Scherrer: Journal of Applied Physics, 2003, 93[2], 907-11