Abstract. Deuterium thermal desorption experiments were performed on B2 FeAl thin films deposited by electron-beam evaporation on Si substrates, annealed at temperatures ranging from 673 to 773 K and 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 temperature ramp), show two well resolved desorption peaks at ~500 and 820 K. The first peak is attributed to the desorption of deuterium contained in FeAl weakly bonding sites of the FeAl lattice, probably point defects (vacancies) produced by the ion implantation process. The second peak is attributed to deuterium release from trapping sites in the FeAl lattice that could be the defect complexes formed by the association of a vacancy in the Fe sublattice and a substitutional Fe atom in the Al sublattice (V_Fe-Fe_Al).

The desorption kinetics can be reproduced by assuming that:

(a) deuterium desorption at ~500 K is controlled by the D₂ surface recombination process with E_des = 1.57±0.02 eV as activation energy;

(b) deuterium desorption at ~820 K is controlled by the release of D atoms from the trap sites, a process which occurs in connection with defect relaxation.

The energy of interaction of deuterium with this trapping site can be estimated to be ~2 eV.

Print publication: Issue 25 (1 July 2002)
Received 3 January 2002, in final form 26 March 2002
Published 14 June 2002