EFFECT OF GAMMA IRRADIATION ON YBa2Cu3O7-δ HIGH TEMPERATURE SUPERCONDUCTORS

Abstract

Samples of YBa 2 Cu 3 O 7-δ superconducting ceramic were prepared and characterized by resistivity measurements using the four probe method and structural analysis using X-ray diffraction (XRD). XRD-patterns show the presence of orthorhombic Y -123 phase with a small fraction of secondary phase, YBa 2 Cu 3 O 5. Samples were irradiated with gamma (γ) rays using Co 60 source with five successive doses of 2.5 Mrad. A monotonic increase in the Tc0 value was observed for radiation dosage up to 10 Mrad. When exposed to even higher γ-doses, the Tc0 value leveled off at a saturation value or decreased. XRD-analysis shows slightly changed values of the lattice constants and a mild shift of diffraction peaks towards a lower 2θ value. These observations indicate structural changes in YBa 2 Cu 3 O 7-δ induced upon gamma irradiation. The present work describes our experimental findings and attempts to offer a theoretical explanation for the effects observed.