Influence of defects produced by fast electrons on superconducting and magnetic properties of YBa2(Cu1-xFex)3O7-y system

YBa2(Cu0.99Fe0.01)3O6.97 and YBa2(Cu0.90Fe0.10)3O7.07 samples were investigated. Gamma-resonance measurements were carried out at room, liquid-nitrogen and liquid-helium temperature before and after irradiation by 3.5 MeV electrons. The temperature of the magnetic transition for the sample with x = 0.10 was measured by temperature scanning of the Mossbauer effect value. It is found that the main irradiation effect is the oxygen redistribution in the basal plane as has been observed before. In this case the critical temperature Tc for the sample with x = 0.10 drops more abruptly than for x = 0.01, whereas the magnetic-ordering temperature Tm increases. The hyperfine magnetic fields remain practically constant. For a fluence of 4 × 1017 electron/cm2 Tm and Tc are nearly the same. The obtained results can be explained on a basis of the model suggested by V.F. Elesin et al. [JETP 101 (1992) 682; JETP Lett. 99 (1991) 237].