Control of grain alignment to fabricate long Y-Ba-Cu-O superconductors with high current density

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Abstract
A directional solidification method has been developed to grow YBa2Cu3Ox samples in excess of 55 mm in length with uniform grain alignment and a‐b planes oriented parallel to the sample length. Using a furnace configuration that yields a negative lateral gradient, the YBa2Cu3Ox grains have been forced to nucleate and grow along the axis instead of at an angle to the sample length. X‐ray pole figures analyses along the entire length at different sections show that the a‐b planes are aligned parallel to the sample length with deviations less than 5° along the growth direction. Transport critical current density (Jc) measurements over the entire length and at different sections of the sample reveal a uniform current density in excess of 7000 A/cm2 at 1.5 T and 77 K.