DIRECTIONAL SOLIDIFICATION OF YBCO RODS FOR CURRENT LEAD APPLICATIONS

A directional solidification procedure for long rods of YBa2CU3O7 - Y2 BaCuO5 composites has been developed based on a vertical Birdgman-like configuration. Single domain rods up to 10 cm in length and a section of 0.15 cm(2) can be fabricated with inductive critical currents abov e 10(5) A/cm(2) at 77K and zero field as measured by means of a SQUID magnetometer. Transport critical currents have been measured at 77K wi th pulsed current up to 800 A flowing at several angles from the a-b p lane, and it is shown that no grain boundary limitations occur when su percurrent cross the a-b planes, in agreement with the observation of reduced concentration of microcracks. The applicability of these textu red rods as current leads will be discussed.