EPR Studies for GdBa2Cu3 O 7-δ Added with Nanosized Ferrite ZnFe2 O 4 Before and After Irradiation by 3 MeV H + Ions

(ZnFe2 O (4)) (x) GdBa2Cu3 O (7-delta) superconducting samples, 0 ae<currency> x ae<currency> 0.40 wt%, were synthesized using a conventional solid-state reaction technique. The prepared samples were investigated using electron paramagnetic resonance (EPR) measurements. EPR measurements were carried out, at different temperatures 100 K ae<currency> T ae<currency> 300 K, for the prepared samples before and after irradiation by 3 MeV protons. An isotropic symmetric EPR line with g factor ae2 is detected for the samples before irradiation, corresponding to Gd3+ ions. A single strong and broad isotropic EPR line is observed for all samples after irradiation with g ae2.65. The broadness is attributed to the superposition of signals resulting from the clustering of Gd3+ ions and the dipole interaction between these ions. The number of spins (N) participating in EPR resonance showed a decrease with increasing temperature, while the activation energy (E (a)) experienced an increase with x up to 0.06 wt% followed by a further decrease.