Abstract
The effect of calcium (Ca) substitution in yttrium (Y) site and nickel (Ni) substitution in copper (Cu) site of Y1–xCax Ba2Cu3–yNiy O7–δ (x = 0.1, 0.2, 0.3 and y = 0.0, 0.1, 0.2), materials prepared by solid state reaction method was investigated. Structural, average oxygen content and electrical resistivity measurements were studied using X-ray Diffraction (XRD), iodometric titration and four-probe method. From XRD analysis, all samples showed the orthorhombic symmetry of YBa2Cu3O7–δ (YBCO). The average oxygen content δ increases with the substitution of Cu by Ni and Y by Ca. Such a phenomenon allows the appearance of oxygen vacancies in the samples. From the electrical resistivity results, critical temperature TC decreases with the content of substitution y of Ni in Y0.9 Ca0.1Ba2Cu3–yNiy O7–δ system. In Y0.9Ca0.1Ba2Cu2.9Ni0.1O7–δ sample (y = 0.1), the variation ΔTC falls only of 7% approximately, whereas a reduction in ΔTC of 40% is observed in the YBa2Cu3–yNiy O7 –δ system. The critical temperatures TC of the Y1–xCax Ba2Cu2.9Ni0.1O7 –δ system (x = 0.1, 0.2 and 0.3) decreases with the content of substitution x of Ca until reaching a minimum at 67 K when x = 0.2, then it increases again.
GRAPHICAL ABSTRACT
![](/cms/asset/cc2c4493-e64b-47e0-9cf4-55d1b99fa42d/tmph_a_1802073_uf0001_oc.jpg)
Disclosure statement
No potential conflict of interest was reported by the author(s).
Correction Statement
This article has been republished with minor changes. These changes do not impact the academic content of the article.