Grain Morphology of YBCO Coated Superconductors Prepared by the Spin and Printing Process on Ni Substrates

The YBCO thick films with c-axis preferred orientation were prepared by the spin and printing processes on Ni substrates (cold rolled Ni, cube textured Ni, and cube textured Ni + self oxided NiO). The results show that the chrysanthemum-(or spherulite) and polygon-shaped grains dominate the microstructure of the YBCO films. The chrysanthemum size is about 0.2 mm-0.5 mm but sometimes reaches Imm, and polygon grains normally appear in the center of the chrysanthemum grains. No chrysanthemum grains appear in the thick films prepared on a silver substrate.