Abstract
The effect of Nd 3.6 Ba 2.4 Cu 1.8 O 5-δ [Nd(422)] dopant on the microstructure and superconducting properties of Nd 0.9 Ba 2.1 Cu 3 O 7-δ [Nd(123)] superconductor melt-processed in air has been studied using various techniques. It has been confirmed that the addition of Nd(422) phase prior to melt-processing significantly enhances the superconducting prosperities of Nd(123) superconductor when melt-processed in air atmosphere. Microstructure analysis using an electron probe micro-analyzer revealed the presence of Nd(422) inclusions in the 123 matrix and these inclusions are better dispersed and more refined in the doped sample. Compared to the undoped sample, the Nd(422)-doped sample showed significant improvement of current density at low fields with largely depressed fishtail peak effect at high temperatures. These results are ascribed to the effect of Nd(422) phase, which yet unoptimized to serve as efficient pinning centers and also allow the introduction of sufficient field induced pinning centers in the sample.