The intermediate YBa2Cu3O7-δ samples of single phase with transitional structure from tetragonal phase to orthorhombic phase are prepared by quenching at different temperatures and investigated systematically. From X...The intermediate YBa2Cu3O7-δ samples of single phase with transitional structure from tetragonal phase to orthorhombic phase are prepared by quenching at different temperatures and investigated systematically. From X-ray diffraction (XRD), R-T curve and ac susceptibility measurements, it can be concluded that the structure transits from tetragonal phase to orthorhombic phase as the quenching temperature decreases; the YBa2Cu2O7-δ samples with tetragonal phase are nonsuperconductive till 4.2K; the critical temperature depends on the degree of orthorhombic distortion in the intermediate samples; the possible existence of a structure phase transition near 100K for the non-superconductive tetragonal phase is discovered for the first time. The electrical conductance property at high temperature region (higher than 100K) for the samples quenched at higher temperature can be explained in terms of the affection of oxygen vacancies.展开更多
Ⅰ. INTRODUCTION Recendy, the research on oxide superconductor has achieved tremendous progress. New records of critical temperature were reported. In this work, the resistivity of Ba-Y-Cu oxide supercondutor and its ...Ⅰ. INTRODUCTION Recendy, the research on oxide superconductor has achieved tremendous progress. New records of critical temperature were reported. In this work, the resistivity of Ba-Y-Cu oxide supercondutor and its density of critical current as a function of temperature are measured by the method of persistent current.展开更多
文摘The intermediate YBa2Cu3O7-δ samples of single phase with transitional structure from tetragonal phase to orthorhombic phase are prepared by quenching at different temperatures and investigated systematically. From X-ray diffraction (XRD), R-T curve and ac susceptibility measurements, it can be concluded that the structure transits from tetragonal phase to orthorhombic phase as the quenching temperature decreases; the YBa2Cu2O7-δ samples with tetragonal phase are nonsuperconductive till 4.2K; the critical temperature depends on the degree of orthorhombic distortion in the intermediate samples; the possible existence of a structure phase transition near 100K for the non-superconductive tetragonal phase is discovered for the first time. The electrical conductance property at high temperature region (higher than 100K) for the samples quenched at higher temperature can be explained in terms of the affection of oxygen vacancies.
文摘Ⅰ. INTRODUCTION Recendy, the research on oxide superconductor has achieved tremendous progress. New records of critical temperature were reported. In this work, the resistivity of Ba-Y-Cu oxide supercondutor and its density of critical current as a function of temperature are measured by the method of persistent current.
