Effects on air-processed NdBCO superconductor bulks when adding a Ba-rich Nd₂Ba₄Cu₂O₉ phase

Employing a novel Ba-rich Nd₂Ba₄Cu₂O₉ (Nd242) phase in the precursor, air-processed NdBCO bulk superconductors were grown by using NdBCO film seeds. To obtain single-phase Nd242 powders, the sintering conditions were adjusted by varying the processing atmosphere and temperature. Furthermore, the influences of adding Nd242 on both the superconducting property and the crystal growth of the NdBCO bulk were investigated. We present experimental evidence suggesting that the addition of Nd242 can effectively improve the superconducting performance of NdBCO bulks, which showed optimal properties when the Ba:Cu ratio in the precursor was 0.80. We also found that the addition of Nd242 caused an increase in growth rate, particularly along the c-axis direction of the NdBCO. Moreover, the effect of the addition of Nd242 on the growth rate was clarified. (paper)