Deuterium retention in boron carbide

The article reviews work on deuterium retention in boron carbide (B4C), which has been considered as a plasma-facing material (low Z-material, with high heat resistance and low chemical erosion). Deuterium retention was studied in sintered boron carbide samples irradiated with 3 keV D ions at room temperature or exposed to a low energy (∼ 200 eV/D) and high ion flux (∼ 1021 m-2 s-1) D plasma at elevated temperatures. Under both ion irradiation and plasma exposure, deuterium is solely accumulated in B4C as D atoms. At 300K, implanted deuterium accumulated mainly in the ion implanted zone. As the irradiation/exposure temperature increased, D atoms began to diffuse into the bulk. Above 600K and high fluences (greater than 1024 D m-2), the bulk accumulation played a major role in D retention. At temperatures around 900K and high ion fluences, the maximum D concentration in the bulk (up to a depth of 50 Dm) was ∼ 0.1 atom %. The diffusivity of deuterium in sintered boron carbide was evaluated to be: D = 1.4 ? 10-5 exp{-(100 ± 10 kJ mol-1)/RT} m2 s-1