Al doping influence on crystal growth, structure and superconducting properties of Y(Ca)Ba2Cu3O7−y whiskers

• Published in: Journal of alloys and compounds Vol. 551; pp. 19 - 23
• Main Authors: Calore, L., Rahman Khan, M.M., Cagliero, S., Agostino, A., Truccato, M., Operti, L.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 25.02.2013; Elsevier
• Subjects: Alloys; Aluminum; Condensed matter: electronic structure, electrical, magnetic, and optical properties; COPPER OXIDE; CRYSTAL GROWTH; Diffraction; Doping; Effects of crystal defects, doping and substitution; Exact sciences and technology; Growth mechanism; Oxide superconductors; Physics; Powders-solid state reaction; SINGLE CRYSTALS; STOICHIOMETRY; SUPERCONDUCTIVITY; SUPERCONDUCTORS; Transition temperature variations; WHISKERS; YBCO superconductors; Oxide superconductors; Powders-solid state reaction; Whiskers; Superconductivity; Growth mechanism; Electrical conductivity; Impurity density; Phase transformations; Superconducting transitions; Doping; Monocrystals; Aluminium additions; High-Tc superconductors; Transport processes; Solid state crystal growth; Barium Copper Yttrium Oxides Mixed; Crystal structure
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2012.08.061

► Optimization of YBCO whiskers synthesis by Al2O3 addition. ► First complete crystal cell characterization of undoped YBCO whiskers. ► Characterization of the doped whiskers structural and electrical properties. ► New important evidences for the bottom-up growth mechanisms. We synthesized Al doped Y(Ca)Ba2Cu3O7−y (YBCO) whiskers via the solid state reaction method. Al doping was systematically varied in the nominal cationic stoichiometry of YBa2Cu3CaTe0.5AlxO7−y, with 0⩽x⩽0.5. The amount of the grown whiskers increases for nominal Al addition up to x=0.05, decreasing for larger concentrations. The concentration of Al incorporated in the crystals (x′) is always higher with respect to the starting stoichiometry and shows a gradient along its length, with a higher amount at the tip regions. The single crystal diffraction analyses show an increasing tetragonal character with increasing x′, with a transition from the orthorhombic to the tetragonal system for x′=0.13, which is in agreement with the worsening of electrical transport properties and disappearing of superconductivity for x′=0.19.