Structure and superconducting properties of nonstoichiometric Y[Ba.sub.2][Cu.sub.3][O.sub.y] annealed at 300°C in a dry argon atmosphere

• Published in: Physics of the solid state 2011-07, Vol.53 (7), p.1448
• Main Authors: Titova, S.G, Blinova, Yu.V, Sudareva, S.V, Bobylev, I.B, Zyuzeva, N.A, Romanov, E.P
• Format: Article
• Language: English
• Subjects: Analysis; Ceramic materials; Ceramics; Superconductors
• ISSN: 1063-7834; 1090-6460
• DOI: 10.1134/S1063783411070286

Using the full-profile X-ray analysis of diffraction lines, the behavior of Y[Ba.sub.2][Cu.sub.3][O.sub.y] nonstoichiometric ceramics upon annealing at 300°C in a dry inert atmosphere has been investigated. It has been established that, in the Y[Ba.sub.2][Cu.sub.3][O.sub.6.3] sample with the initial tetragonal structure, this treatment leads to nucleation of an orthophase with a low degree of rhombicity, which becomes prevailing after annealing for 56 h. In this case, superconductivity with an initial temperature of the transition of ~50 K occurs in the sample. In the Y[Ba.sub.2][Cu.sub.3][O.sub.6.7] sample with the initial orthorhombic structure, the orthophase with a somewhat enhanced rhombicity arises during annealing and becomes prevailing after annealing for 56 h; in this case, [T.sub.c] of the system grows from 57 to 63 K. Data of the magnetic measurements for both cases can be interpreted as the presence of two orthorhombic phases with different temperatures of transition to the superconducting state in the samples after annealing.