We have studied oxygen deficient GdBa2Cu3O7-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 λtr=0.31 which suggests a weak electron-phonon coupling in high-Tc oxides.
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