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

摘要

A method of fabricating bulk superconducting material including RBa. sub.2 Cu.sub.3 O.sub.7- comprising heating compressed powder oxides and/or carbonates of R and Ba and Cu present in mole ratios to form RBa.sub.2 Cu.sub.3 O.sub.7- in physical contact with an oxide single crystal seed to a temperature sufficient to form a liquid phase in the RBa.sub.2 Cu.sub.3 O.sub.7- while maintaining the single crystal seed solid to grow the superconducting material and thereafter cooling to provide a material including RBa.sub.2 Cu.sub.3 O. sub.7- . R is a rare earth or Y or La and the single crystal seed has a lattice mismatch with RBa.sub.2 Cu.sub.3 O.sub.7- of less than about 2% at the growth temperature. The starting material may be such that the final product contains a minor amount of R.sub.2 BaCuO.sub.5.