TRITIUM MIGRATION IN VAPOR-DEPOSITED BETA-SILICON CARBIDE

Tritium diffusivities and solubilities have been measured for vapor-deposited beta-silicon carbide. The solubility measurements were performed over the temperature range of 1000 to 1600-degrees-C and the pressure range 0.01 to 1.0 atm. Diffusivities were determined for the temperature range of 1100 to 1500-degrees-C. The magnitude of the diffusivity was much lower than that for metals and the activation energy was much higher. The measured solubility had a negative heat of solution and, when corrected for surface absorption, varied linearly with the square-root of pressure. The low diffusivity along with the apparent negative heat of solution are indicative of trap-controlled migration of tritium in the silicon carbide.