Deuterium retention in W, W1%La, C-coated W and W2C

This paper reports the results of a systematic investigation into retention of deuterium implanted into various forms of W including: reduction-rolled , powder-metallurgy foil; discs of W1%La alloy; W and W2C prepared by chemi cal vapor deposition (CVD) and annealed C-coated W discs, Deuterium was imp lanted at energies of 0.5 keV/D with fluxes of similar to3 x 10(19) D/m(2) s and fluences of 3 x 10(23) D/m(2), for samples at temperatures from 23 de greesC to 400 degreesC. Retained deuterium quantities were measured using t hermal desorption spectroscopy (TDS). Retention in annealed CVD-W and W1%La . for implantation temperatures less than 200 degreesC, is below that in an nealed W foil, indicating that trapping may be affected by the different ma terial defect structures. For implantation temperatures less than 300 degre esC, retention in CVD-W2C is somewhat higher than that in CVD-W, indicating trapping could be enhanced by trace carbon impurities, differences in W2C material structure and recoil carbon-induced material damage. Implantation into C-coated W resulted in orders of magnitude more retention than in unco ated material, because of trapping in the carbon coating. (C) 2001 Elsevier Science B.V. All rights reserved.