X-ray and high-resolution neutron diffraction studies on Nd _x Y_1-x Ba₂Cu₃O_7-δ Superconductors

A synthesis of neodymium-substituted YBCO superconductor Nd _x Y_1-x Ba₂Cu₃O_7-δ (x=0,0.25,0.5,0.75,1) has been done using a dissolved method in order to obtain homogeneous crystals and higher critical current density. The effects of the substitutions on the structural and magnetic properties of the superconductors after sintering at 970 ^â̂̃C have been examined. Crystallinity of the synthesized powders was confirmed using X-ray and high-resolution neutron diffraction (XRD and HRPD) techniques. Rietveld analyses for both diffraction data sets gave increasing lattice parameters with addition of Nd content and decreasing orthorhombicity. Such addition also caused a decrease in occupancy of the oxygen in the O(4) site. Further investigation using SQUID showed critical temperature of the superconductors between 90.9 and 92.0 K. The critical current density (J _c ) was calculated from the magnetic hysteretic loop at 5 K as 40 kA cm^-2 for Nd _0.25Y_0.75Ba₂Cu₃O _7-δ sample and 100 kA cm^-2 for Nd _0.5Y_0.5Ba₂Cu₃O_7-δ sample. We also found that increasing Nd content on the Nd _x Y _1-x Ba₂Cu₃O_7-δ superconductor samples can improve their resilience of superconductivity and critical current density.