Localized large superconducting critical currents in Ba2Y1Cu3O9−y

Magnetization measurements of powder and sintered samples of Ba2Y1Cu3O9−y have been made at 77 K. Excellent critical current densities Jc’s of about 3×104 A/cm2 at 10 kOe were estimated for the powder samples, which consisted of single-crystal particles of ∼3 μm in dimension. These Jc’s were about two orders of magnitdue larger than those of the sintered sample.