TRITIUM MIGRATION IN VAPOR-DEPOSITED BETA-SILICON CARBIDE

Tritium diffusivities and solubilities have been measured for vapor-de posited beta-silicon carbide. The solubility measurements were perform ed over the temperature range of 1000 to 1600-degrees-C and the pressu re range 0.01 to 1.0 atm. Diffusivities were determined for the temper ature range of 1100 to 1500-degrees-C. The magnitude of the diffusivit y was much lower than that for metals and the activation energy was mu ch higher. The measured solubility had a negative heat of solution and , when corrected for surface absorption, varied linearly with the squa re-root of pressure. The low diffusivity along with the apparent negat ive heat of solution are indicative of trap-controlled migration of tr itium in the silicon carbide.