Preparation of Y-Ba-Cu-O superconductors with high critical current density by unidirectional melt solidification

Y-Ba-Cu-O superconductors with high Jc have been prepared by a unidirectional melt solidification method. Uniformly oriented plate-shaped YBa2Cu3O7-y crystals containing small particles of Y2BaCuO5 have been grown successfully using the material with the nominal composition of Y1+xBa2-xCu3-2xOz (x&le0.4) as a starting material. The Jc values of the unidirectionally solidified Y-Ba-Cu-O samples, measured at 77 K using a four-probe method with continuous direct current, were 4600 and 12000 A/cm2 in 1 and 0.25 T, respectively. These values nearly coincided with those estimated from magnetization hysteresis loops using Bean's critical state model.