Enhanced magnetic flux pinning in nano-composite Y-Ba-Cu-O superconductors

Nano-composite Y-Ba-Cu-O (YBCO) superconductors containing non-superconducting phase inclusions of composition Y2Ba4CuMOy (Y-2411), where M = Bi and Ag, embedded in the YBa2Cu3O7−δ (Y-123) superconducting matrix have been fabricated successfully. The Y-2411 phase, which typically has dimensions in the range 20-300 nm depending on the element M, is characterized by a double perovskite cubic crystallographic structure and forms effective flux pinning sites in bulk YBCO. A direct correlation between the Y-2411 phase inclusion content in the Y-123 matrix and increased magnetic flux pinning has been observed in these materials. The flux pinning force and the critical current densities increase by an order of magnitude for nano-composites compared to Y-Ba-Cu-O fabricated without nano-scale inclusions, confirming their potential for improved current carrying performance and for use in high field engineering applications.