Ion-driven permeation and surface recombination coefficients of deuterium for silver

Abstract

The steady-state flux of deuterium permeation through an iron membrane (99.99 + % purity, 0.14 mm thickness) driven by a deuterium ion beam (5 keV D3+, 1.0 × 1015 D-atoms cm−2s−1) was measured in the range of 30–1050°C. The permeation flux increased with increasing temperature above 200°C whereas it was roughly constant below 150°C. Such temperature dependence was observed for nickel and copper as well, and has been ascribed to the transition in the rate-limiting processes of the deuterium transport in the membrane. The recombination coefficient of deuterium on iron surface was evaluated from the permeation flux density. In the case of α-iron, the evaluated value agreed with a semitheoretical one estimated using literature data of adsorption probability and solubility. This agreement indicates that the release kinetics reflects the activation barrier for hydrogen (deuterium) adsorption.