X-ray investigation of amorphization of ion-implanted Al-Mn

Structural modifications of Al thin films implanted with Mn+ ions at liquid -nitrogen-temperature (LNT) (similar to 77 K) were studied by X-ray powder diffraction. For each Mn concentration, strain and crystallite size were de termined from X-ray line broadening For room-temperature (RT) implantation, amorphization begins at approximately 1 at.% Mn by thermally activated loc al atomic rearrangements which lead to the formation of amorphous zones or clusters. At LNT, a supersaturated solid solution is formed at mean Mn conc entrations below 5 at.% Mn. At higher Mn concentrations, amorphous clusters formed throughout the sample in regions where the strain level reached a t hreshold value at a critical Mn concentration of 8.5%. Present investigatio ns suggest a preferential short-range migration of Mn atoms from the remain ing crystalline material to amorphous regions formed at LNT causing an Mn d epletion and partial recovery of the crystalline regions. The maximum value of the atomic displacements U-st was found to be 0.13 +/- 0.01 Angstrom an d the maximum value of the strain was (1.65 +/- 0.15) x 10(-3). The lattice constant a(0) of the host (Al) lattice was found to decrease by about 0.13 %. (C) 1999 Elsevier Science B.V. All rights reserved.