Seed crystals with improved properties for melt processing superconductors for practical applications

A method of fabricating bulk superconducting material including RBa2Cu3O7- delta comprising heating compressed powder oxides and/or carbonates of R and Ba and Cu present in mole ratios to form RBa2Cu3O7- delta in physical contact with an oxide single crystal seed to a temperature sufficient to form a liquid phase in the RBa2Cu3O7- delta while maintaining the single crystal seed solid to grow the superconducting material and thereafter cooling to provide a material including RBa2Cu3O7- delta . R is a rare earth or Y or La and the single crystal seed has a lattice mismatch with RBa2Cu3O7- delta of less than about 2% at the growth temperature. The starting material may be such that the final product contains a minor amount of R2BaCuO5.