Deuterium thermal desorption from FeAl thin films

Abstract

Deuterium thermal desorption experiments were performed on B2FeAl thin films deposited by electron-beam evaporation on Sisubstrates, annealed at temperatures ranging from 673 to 773 Kand implanted with 20 keV D2 ions at fluences of 3×1016 D2+ cm-2. D2 desorption spectra,recorded in isochronal heating conditions (0.5 K s-1 temperatureramp), show two well resolved desorption peaks at ~500 and 820 K. The first peak is attributed to thedesorption of deuterium contained in FeAl weakly bonding sitesof the FeAl lattice, probably point defects (vacancies)produced by the ion implantation process. The second peak isattributed to deuterium release from trapping sites in the FeAllattice that could be the defect complexes formed by theassociation of a vacancy in the Fe sublattice and asubstitutional Fe atom in the Al sublattice(VFe-FeAl).The desorption kinetics can be reproduced by assuming that:(a) deuterium desorption at ~500 K is controlled by theD2 surface recombination process with Edes = 1.57±0.02 eV as activation energy;(b) deuterium desorption at ~820 K is controlled by therelease of D atoms from the trap sites, a process which occursin connection with defect relaxation.The energy of interaction of deuterium with this trapping site can be estimated to be ~2 eV.