STRUCTURAL MODIFICATIONS INDUCED BY ELECTRONIC-ENERGY LOSS IN NI3B IRRADIATED WITH GEV HEAVY-IONS

Crystalline Ni3B samples have been irradiated with GeV heavy ions (fro m O-16 to U-238) at low temperature in order to study the damage induc ed in this compound by ion electronic energy loss. Electrical resistan ce measurements were performed in situ during irradiation and during a nnealing. Subsequent X-ray diffraction data and transmission electron microscopy observations reveal a change of the radiation damage proces s as a function of the electronic stopping power (dE/dx)(e). At low (d E/dx)(e) isolated defects are created, while at high (dE/dx)(e) irradi ation generates continuous amorphous tracks. Amorphous inclusions (dis continuous 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 roo m temperature over a period of a few months.