THE EFFECTS OF SURFACE CONTAMINATION ON ABSORPTION AND DESORPTION OF DEUTERIUM IN BERYLLIUM AND BERYLLIUM-OXIDE

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 approximate to 10(18) exp(-0.8 eV/kT) at/m(3)(Pa)(1/2) possibly indicative of the formation of hydroxide bonds; the diffusivity is greater than or equal to 7x10(-5) exp(-2.1 eV/kT) m(2)/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 X 10(27) exp(- 0.58 eV/kT) at/m(3)(Pa)1/2. The solubility for deuterium in bulk Be was found to be 7 x 10(27) exp(-1.0 eV/kT) at/m(3)(Pa)(1/2), and the bulk diffusivity is 8 x 10(-9) exp(- 0.36 eV/kT) m(2)/s.