Correction of impurity effects on the characterization of YBCO superconductor

We have corrected the impurity effect on the characterization of Y1-xCaxBa2 Cu3Oy superconductors prepared by the solid state reaction method. Although the samples have sharp superconducting transition, tiny peaks of BaCuO2 ph ase are included in the X-ray diffraction (XRD) patterns suggesting a part of Ca ions entered onto the Ba-site. Rietveld analysis of the XRD patterns shows that about 10% of Ca ions occupy the Ba-site regardless of the Ca con tent. Various superconducting parameters such as the oxygen content, hole c oncentration, etc., are compared before and after the impurity correction. Our results show that a small amount of impurity phase may have large effec ts on the characterization of superconductors. (C) 2000 Elsevier Science B. V. All rights reserved.