Study of superconducting properties of oxygen deficient GdBa₂Cu₃O_7-y by a heating cycle technique

We have studied oxygen deficient GdBa₂Cu₃O_7-y samples by heating cycle technique and correlated the resistivity data with the oxygen deficiency derived from TGA. An orthorthombic to tetragonal phase transformation was found at about 720 K and it is consistent with that derived from the X-ray data. The resistivity is hysteretic cooling and shows semiconducting behavior for y≥0.7. Localization was found for samples with semiconductive properties. The electron-phonon coupling constant derived from the electric and magnetic measurements is λ_tr=0.31 which suggests a weak electron-phonon coupling in high-T_c oxides.