The primary prerequisite for successful single grain growth of a REBa2Cu3Oy bulk superconductor is the determination of an optimized growth temperature window of the given system. In our recent work, addition of 20 wt. % of Dy2BaCuO5 (Dy-211) to the GdBa2Cu3O7-δ bulk sample [(Gd,Dy)BCO] enhanced superconducting properties. Then, different isothermal dwell times were tested at various undercooling temperatures to find the temperature window appropriate for the single grain growth by a top-seeded infiltration growth process performed in air. Nearly perfect single-grain (Gd,Dy)BCO crystals were grown. A systematic and detailed investigation of the microstructure, composition, and physical properties of the single-grain (Gd,Dy)BCO superconductors was carried out. The superconducting transition was sharp with the onset at 92.9 K. The field dependence of the critical current density (Jc) was determined at several temperatures. At 77 K, a self-field Jc of 55 kA/cm2 and a trapped field of 0.19 T were achieved. The possibilities for further improvement of the microstructure and superconducting performance are discussed.
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