Phase equilibria and primary crystallisation field for Sm1+yBa2-yCu3O7 at various p(O2)

• Published in: Journal of alloys and compounds Vol. 381; no. 1-2; pp. 320 - 326
• Main Authors: WENDE, C, SCHÜPP, B, KRABBES, G
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier 03.11.2004
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Cuprates superconductors (high tc and insulating parent compounds); Exact sciences and technology; Materials science; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Phase diagrams of other materials; Physics; Superconductivity; Samarium oxides; Crystal growth; Phase diagrams; Annealing; Inorganic compounds; High-Tv superconductors; Transition element compounds; Crystallization; Liquidus; Controlled atmospheres; Rare earth compounds; Partial pressure; Barium oxides; High-Tc superconductors; Phase equilibria; Chemical potential; Thermal analysis; Quaternary compounds; Copper oxides; Melt texturing
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2004.04.093

Phase relations in the Sm-Ba-Cu-O system in air have been reconsidered and the topology at the liquidus surface has been consistently constructed from both new experimental investigation as well as critical review of literature data. Subsolidus phase equilibria near the superconducting Sm1+x Ba2-xCu3O7 ("Sm123") phase have also been investigated at various oxygen partial pressures, revealing the strong influence of the oxygen chemical potential on the extension of the homogeneity region of the Sm123 phase. The decomposition temperature of Sm123 decreases rapidly from 1070 DGC down to 1010 DGC with the Sm excess x increasing from ~0 to ~0.5. For x > 0.5 the decomposition temperature is constant indicating an invariant reaction which marks the lowest temperature at which the Cu-rich melt is in equilibrium with both Sm 123 and Sm2BaCuO5 ("Sm211"). For Cu-poor melts this temperature is 1030 deg C in air (0.21 bar O2). Implications of the results with respect to both sample growth during melt texturing and post annealing (decomposition of Sm-rich Sm 123) in different atmospheres are being discussed. A p(O2)-T-diagram for equilibria containing Sm-rich Sm123 is derived.