Self-diffusion studies of Si in amorphous precursor-derived ceramics (Si3BC4.3N2 and Si2.6C4.1N2.3) were carried out in order to compare the atomic transport properties of B-containing and B-free material in the Si–(B)–C–N system. Ion-implanted stable 30Si isotopes were used as tracers, and secondary ion mass spectrometry was used for depth profiling. The experimentally determined diffusivities were lower by a factor of 10 for Si3BC4.3N2 than for Si2.6C4.1N3.3 within the entire temperature range investigated. The data obeyed Arrhenius behaviour:

D (m2/s) = 1.0 x 10-3 exp[-5.7(eV)/kT]

The results were consistent with a diffusion mechanism that was mediated by vacancy-like defects in the amorphous ceramics.

H.Schmidt, G.Borchardt, S.Weber, H.Scherrer, H.Baumann, A.Müller, J.Bill: Journal of Non-Crystalline Solids, 2002, 298[2-3], 232-40