Evidence for palladium droplet formation due to deuterium ion irradiation

High-resolution scanning electron microscopy (SEM) has revealed that pallad ium (Pd) crystallites formed on the so-called "matrix" are transformed into spheres by deuterium (D)-ion irradiation at low-keV. These Pd spheres are possibly liquid droplets during ion irradiation, which are then quenched in to solid spheres upon switching-off of the ion beam. The target temperature s required for this geometrical transformation are around one-third of the melting point of Pd, presumably indicating that absorbed D atoms might decr ease the particles' melting point dramatically. (C) 1999 Elsevier Science B .V. All rights reserved.