Investigations of YBaCuO Materials with Near-Room-Temperature ResistivityTransitions

摘要

This final technical report describes the continual superconductivity research onthe materials and structural phases responsible for the above 200-K superconducting transitions, their synthesis conditions, and the study of the physical properties associated with these transitions. Resistive transitions having superconducting-like character have been observed in multi-phase ceramic YBaCu0 samples and on surfaces of nominal YBa2Cu3O7 single crystals in the temperature range of 260 K to 340 K. The appearance of these transitions appears to require certain experimental measuring conditions including an oxygen atmosphere during measurments. Magnetization studies on these materials show a flux-trapping hysteretic behavior at similar temperatures, i.e., a more