Orientation of High-Critcal-Temperature Superconductors by Optical Processing

The inability to fabricate copper-based superconductors capable of transporting or circulating high current densities over large volumes has severely limited applications for wires and levitation. Difficulties in texturing these ceramic materials is due to the requirement for nearly perfect grain boundaries resulting from the small quasi particle coherence lengths. Control of the morphology and nature of defects or grain boundaries effecting vortex pinning is the key to expanding applications of these materials. We propose a method to create rapid melting and solidification in the presence of a giant thermal gradient along the c-axis of mechanically aligned bulk YBa2Cu307-x substrates. A fast-moving and directed, giant thermal gradient is energized by continuous wave C02 laser radiation. Objectives are directed toward developing a technology for fabricating large structures of high Jc copper-based superconductors relevant to wire and levitation applications. Experiments will be performed to define the best compositional pathways and optical parameters to control the ceramic morphology. Large structures of textured ceramics with a high density of pinning sites will find numerous NASA applications for magnetically levitated static and dynamical bearing systems requiring large forces, restoring forces (stiffness) and minimal rotational drag forces.