Simultaneous Substitution of Y and Ba by Ca in YBCO
A series of samples of Y1-xCaxBa2Cu3Oy (YCBCO) were synthesized with 0.05≤x≤0.3 and characterized by DC magnetization, X-ray diffraction (XRD), and Rietveld refinement. It was found that Ca replaces Y and Ba in YBa2Cu3Oy (YBCO) simultaneously, and the amount of Ca in the Y and Ba positions is estimated by the refinement，respectively. The experimental results showed that the structural changes had a close correlation with Tc. With careful analysis of the change of the Tc below and above x=0.2 and the changes of the bond lengths, such as Cu(2)-O(2) and Cu(2)-O(3), it is suggested that the Ca substitution for Y suppresses the Tc more strongly than that for Ba.
Yafang Han et al.
L. Zhang et al., "Simultaneous Substitution of Y and Ba by Ca in YBCO", Materials Science Forum, Vols. 546-549, pp. 2123-2126, 2007