Homovalent Ho/Bi substitution effect on characteristic properties of Bi-2212 superconducting ceramics

In the current work, the effect of trivalent Ho/Bi partial replacement on the fundamental characteristic features such as the general crystallinity quality quantities, dc electrical resistivity, superconducting, degree of granularity, strength quality of intra- and inter-grain boundary couplings in the oxygen-deficit multi-layered perovskite-based Bi2.1Sr2.0Ca1.1Cu2.0Oy (Bi-2212) superconducting ceramics is examined by powder X-ray diffraction (XRD), temperature-dependent electrical resistivity (rho-T), and Archimedes water displacement methods. The polycrystalline Bi2.1-xHoxSr2.0Ca1.1Cu2.0Oy compounds are produced by the conventional ceramic method within the molecular ratio intervals 0.00 <= x <= 0.30. All the experimental findings show that the trivalent holmium (Ho3+) impurities are successfully substituted by the bismuth (Bi3+) particles in the Bi-2212 crystal system. Besides, the optimum holmium concentration for the bulk Bi-2212 superconducting ceramics is recorded to be x = 0.01. XRD results indicate that the Bi-2212 material prepared by the optimum Ho/Bi substitution possesses the maximum average crystallite size (60 nm), Bi-2223 superconducting phase volume fraction (33.48%), c-axis length (32.55 angstrom), and Lotgering index (0.48) parameters. In this respect, the best sample with particle distributions well linked each other has the maximum bulk density value of 6.04 g/cm(3) and minimum degree of granularity of 4.13%. It is obvious that the optimum (excess) Ho/Bi partial substitution supports the enhancement in the density (granular structure nature) of Bi-2212 compound. Moreover, dc electrical resistivity measurement results show that the optimum homovalent Ho/Bi partial substitution in the Bi-2212 superconducting matrix leads to increase the homogeneities in the oxidation state of superconducting grains and especially densities of active and effective electronic states (DOS) at Fermi energy level. To sum up, this study indicates that the optimum trivalent Ho/Bi partial substitution increases the usage of Bi-2212 superconducting materials in much more application fields.

Automated summary

The study demonstrates that the optimum trivalent Ho/Bi partial substitution enhances the crystal structure and superconducting properties of Bi-2212 materials, indicating its importance in improving performance.