The effects of surface contamination on absorption and desorption of deuterium in beryllium and beryllium oxide

Abstract

Deuterium thermal absorption and desorption experiments were conducted in high-purity Be, BeO and Be2C samples. Ion-beam analysis was used to measure the surface contamination and near-surface deuterium concentration (up to depths of 500 nm). For bulk BeO the deuterium solubility is small, with S ≈ 1018 exp(-0.8 eV/kT) at/m3(Pa) 1 2, possibly indicative of the formation of hydroxide bonds; the diffusivity is ≥ 7 × 10-5 exp(-2.1 eV/kT) m2/s. In deliberately corroded Be samples the deuterium surface concentration was about 0.02 at% where there was little or no carbon contamination, and up to 1.6 at% when the carbon and oxygen contents were similar. This implies the presence of large concentrations of trapped deuterium at or near the surface. The approximate solubility of bulk Be2C samples was estimated as 3.4 × 1027 exp(-0.58 eV/kT) at /m3(Pa) 1 2. The solubility for deuterium in bulk Be was found to be 7 × 1027 exp(-1.0 eV/kT) at /m3(Pa) 1 2, and the bulk diffusivity is 8 × 10-9 exp(-0.36 eV/kT) m2/s. © 1994.