Mass density of glassy Pd80Si20 during low-temperature light ion irradiation

Changes in mass density of amorphous Pd80Si20 were monitored in situ during irradiation with He2+ and H+ ions at temperatures below 100 K and during s ubsequent thermal treatment. The mass density decreased with increasing ion fluence and exponentially approached a saturation value of -1.2%, correspo nding to a recombination volume of 190 atomic volumes, The initial swelling rate was 2.3 atomic volumes/displaced atom. The mass density of the irradi ated material increased during subsequent thermal treatment, and the irradi ation-induced decrease of the mass density recovered completely at room tem perature.