Superconducting properties of YBaCuO ceramic doped with Ca and Zn

The addition of elements as impurities to superconducting compounds generally varies their physical properties and more information on the possible mechanisms of superconductivity is obtained through impurity studies. It is known that the rare‐earth replacement of Y and Ba in YBaCuO superconductor (Y‐123) has a small effect on the superconducting transition temperature (with few elements proving to be an interesting exception). In contrast, the transition metal substitutions for Cu sites have a clear effect on Y‐123 properties. Impurities mainly substitute the Cu sites in the CuO chain (as Co) or in the CuO2 plane (as Zn). In this study, we investigate the effect of Ca and Zn substitutions on the structural, electrical and magnetic properties of a series of Y1−xCaxBa2(Cu0.98Zn0.02)3O7−δ ceramics. The Ca‐doped Y‐123(Zn) are prepared by conventional solid‐state reaction method and characterized by X‐ray diffraction (XRD),scanning electron microscopy (SEM), differential thermal analysis–thermogravimetric analysis (DTA–TGA), and electrical and magnetic measurements (magnetization; susceptibility). Copyright © 2010 John Wiley & Sons, Ltd.