Self-diffusion of ³⁰Si in polycrystalline β-SiC

Abstract

The ³⁰Si lattice self-diffusion coefficients in high-purity β-SiC are reported for the temperature range 2283 to 2547 K and may be represented by the expression

$$D_{Si}^* = (8.36 \pm 1.99) \times 10^7 \exp \left[ {\frac{{(9.45 \pm 0.05 eV atom^{ - 1} }}{{kT}}} \right]cm^2 \sec ^{ - 1} $$

. Decomposition of the sample at the grain boundaries prevented detection of diffusion along these paths of fast transport. Lattice diffusion of Si was concluded to occur by a mechanism involving a direct jump to the nearest Si vacancy without the previous occupation of a normally unfilled position. A comparison of C and Si diffusion in this material is also given.