Silicon tracer diffusion in single crystalline 2/1-mullite measured by SIMS depth profiling

We have measured the silicon tracer diffusivity (30Si) in single crystalline 2/1-mullite parallel to the crystallographic b- and c-axes, respectively. No significant difference between the b- and c-directions was found within the experimental error of 30%. An activation enthalpy of 612 kJ mol−1 and a pre-exponential factor of 7.3 × 10−2 m2 s−1 were determined from the silicon diffusivity data. In the investigated temperature range from 1311 °C to 1525 °C the silicon diffusivity is about two orders of magnitude lower than the oxygen diffusivity.