Improved microstructural features in screen printed NdBCO thick films on YSZ substrates

摘要

An investigation of the effect of using Ba-rich precursors, Nd0.9Ba2.1Cu3Oy + 15 wt% Nd3.6Ba2.4Cu1.8Oz, on the melt growth, microstructure and superconducting properties of NdBCO screen-printed thick films on YSZ substrates has been carried out. The presence of unreacted powder (BaCuO2) in the precursor increased the amount of liquid and resulted in the formation of a large grain size. However, the addition of Nd-422 was effective in stabilising the liquid viscosity at the processing temperature and reducing the film/substrate interaction. As a consequence, high transition temperatures and sharp superconducting transitions were obtained. It has been found that the cooling rate affects the texture orientation, grain size and quality in addition to the interaction between the film and the substrate. The magnetic flux dynamics have been investigated using the Magneto-Optical (MO) technique at various low temperatures and different external applied magnetic fields. The magnetization critical current density was 4.1 x 10(4) A/cm(2) at 5 K and zero field.