X-Ray and High-Resolution Neutron Diffraction Studies on Nd x Y1−x Ba2Cu3O7−δ Superconductors
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A synthesis of neodymium-substituted YBCO superconductor Nd x Y1−x Ba2Cu3O7−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 ∘C 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 Nd0.25Y0.75Ba2Cu3O7−δ sample and 100 kA cm−2 for Nd0.5Y0.5Ba2Cu3O7−δ sample. We also found that increasing Nd content on the Nd x Y1−x Ba2Cu3O7−δ superconductor samples can improve their resilience of superconductivity and critical current density.
KeywordsYBCO superconductor Dissolved method X-ray and high-resolution neutron powder diffraction Structure dc-susceptibility
This work was partially supported by “Hibah Riset Pascasarjana” provided by DP2M, Directorate General of Higher Education (DGHE) of Indonesia, under the contract No. 762/I2.7/PM/2011. One of us (WGS) would like to thank DGHE for the scholarship through BPPS Program and funding of Sandwich Program to Japan in 2011. The use of SQUID magnetometer at RIKEN Nishina Center, Japan, is gratefully appreciated.
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