Microstructural study of a YBCO multilayer coated conductor cylinder

Multilayered YBCO films with a total thickness of 2.7 μm have been grown successfully on buffered curved NiW RABiTS by pulsed laser deposition to demonstrate the feasibility of fabricating in situ a multi-turn superconducting coil on a cylindrical heated former. In the multilayered structure of YBCO thin films insulated by strontium titanate (STO), biaxial texture with c-axis orientation can be transmitted from the substrate to all of the layers with no loss in quality. The critical temperature is maintained as the number of layers is increased but a small increase in transition width is observed. No interfacial diffusion or chemical reaction was observed at the interfaces investigated by TEM and STEM. Pores were commonly found at 'dips' in the STO surfaces after the total YBCO thickness exceeded 1.1 μm