Structural modifications induced by electronic energy loss in Ni₃B irradiated with GeV heavy ions

Crystalline Ni3B samples have been irradiated with GeV heavy ions (from O-16 to U-238) at low temperature in order to study the damage induced in this compound by ion electronic energy loss. Electrical resistance measurements were performed in situ during irradiation and during annealing. Subsequent X-ray diffraction data and transmission electron microscopy observations reveal a change of the radiation damage process as a function of the electronic stopping power (dE/dx)(e). At low (dE/dx)(e) isolated defects are created, while at high (dE/dx)(e) irradiation generates continuous amorphous tracks. Amorphous inclusions (discontinuous tracks) are most likely formed in the intermediate (dE/dx)(e) range. The amorphous phase induced by swift heavy ion irradiation, different from that formed by quenching techniques, is unstable at room temperature over a period of a few months.