Effect of Oxygen Treatment on Electrical Properties of YBa<sub>2</sub>Cu<sub>3</sub>O<sub>6.9</sub>

Abstract

The superconducting compound, Y-Ba-Cu-O, was prepared and treated (transfer of the sample from the furnace, mounting in the equipment and measurements, etc.) in the pure oxygen atmosphere in order to prevent absorption of moisture and carbon dioxide, as well as to hinder oxygen removal from the oxide. The electrical resistivities were measured under the initial oxygen pressure of 2.02×106Pa. The oxygen pressing and heating treatment at 2.02×106Pa for 24h at 363K was conducted for several times, and the effects of the treatment on the superconducting transition temperature (Tc) and on the resistivities were investigated. By the oxygen pressing and heating treatment for the Y-Ba-Cu-O system, the on set and off set Tc decreased, and the resistivities increased. On the other hand, the oxygen pressing treatment at the room temperature gave a constant Tc, while the resistivities increased. The dry air pressing and heating treatment decreased the off set Tc, and enhanced the resistivities greatly. By the dry air pressing treatment at room temperature, on the contrary, the same Tc was kept and the resistivities was slightly increased.