Enhanced superconducting properties in infiltration processed Y–Ba–Cu–O single-grain superconductor with nano-sized pinning centers

• Single-grain YBCO superconductor with nano-sized pinning centers was successfully fabricated.
• Large amount of fine Y-211 inclusions with a mean size 50 nm are introduced in Y-123 matrix.
• The maximum levitation force reaches 29.09 N for a 16 mm diameter YBCO sample.
• The maximum trapped field of 0.36362 T is present at the center of the sample.
• The calculated zero-field Jc property at 77 K reaches 8.41 × 104 A/cm2.

Single-grain Y–Ba–Cu–O (YBCO) superconductor with nano-sized pinning centers was successfully fabricated by a novel top-seeded infiltration and growth (TSIG) technique using a solid source pellet of composition nano-Y2O3 + BaCuO2. Microstructural observation indicates that large amount of fine Y2BaCuO5 inclusions with a mean size 50 nm are successfully introduced in YBa2Cu3O7−x superconducting matrix, which can act as more effective pinning centers for improving the bulk performance. Measurements of superconducting properties show that, the maximum levitation force reaches 29.09 N for a 16 mm diameter sample, corresponding to a force density 14.47 N/cm2, and a maximum trapped field of 0.36362 T is present at the center of the sample after magnetization by a permanent magnet (B = 0.5 T). The calculated zero-field Jc property at 77 K reaches 8.41 × 104 A/cm2, nearly 48% higher than the sample fabricated by the conventional TSIG technique. These results prove the superior performance of the nano-composited YBCO single-grain superconductor infiltration processed with our method.