Island Growth of Y2BaCuO5 Nanoparticles in (211~1.5 nm/123~10 nm)xN Composite Multilayer Structures to Enhance Flux Pinning of YBa2Cu3O7-Delta Films
OHIO STATE UNIV COLUMBUS DEPT OF MATERIALS SCIENCE AND ENGINEERING
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A controlled introduction of second-phase Y2BaCuO5 211 nanoparticles into YBa2Cu3O7-8123 thin films was achieved for the first time for the purpose of increasing flux pinning. The island-growth mode of 211 on 123 was utilized to obtain an area particle density 10exp 11 sq cm of 211 thick-disk-shaped nanoparticles in individual layers. Composite layered structures of 211y nanoparticles123zxN were deposited by pulsed laser deposition on LaA1O3 substrates, with N bilayers 24 to 100, y thickness 1 to 2 nm, and z thickness 6 to 15 nm assuming continuous layer coverage. With 211 addition, the critical current densities at 77 K were higher at magnetic fields as low as 0.1 T and increased as much as approximately 300 at 1.5 T. The superconducting transition temperature was reduced by approximately 2 to 4 K for 211 volume fraction 20. Reinitiation of 123 growth after every 211 layer resulted in a smooth and flat surface finish on the films and also greatly reduced surface particulate formation especially in thicker films 1 micrometer.
- Inorganic Chemistry