Control of Flux Pinning in MOD YBCO Coated Conductor

Two different types of defect structures have been identified to be responsible for the enhanced pinning in metal organic deposited YBCO films. Rare earth additions result in the formation of nanodots in the YBCO matrix, which form uncorrelated pinning centers, increasing pinning in all magnetic field orientations. 124-type intergrowths, which form as laminar structures parallel to the ab-plane, are responsible for the large current enhancement when the magnetic field is oriented in the ab-plane. TEM studies showed that the intergrowths emanate from cuprous containing secondary phase particles, whose density is partially controlled by the rare earth doping level. Critical process parameters have been identified to control this phase formation, and therefore, control the f 24 intergrowth formation. This work has shown that through process control and proper conductor design, either by adjusting the composition or by multiple coatings of different functional layers, the desired angular dependence can be achieved.