The Comparisons Between Y-123 and Y-124 Superconductor Substituted with Ca at the Cu-Site

• Published in: Journal of superconductivity and novel magnetism 2013-04, Vol.26 (4), p.953-957
• Main Authors: Hidayah, H. N., Yahya, S. Y., Azhan, H., Azman, K., Hawa, J. S., Norazidah, A. W.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Copper; Critical currents; Cuprates superconductors (high tc and insulating parent compounds); Current density; Electrical resistivity; Exact sciences and technology; Field emission; Magnetic fields; Magnetic Materials; Magnetism; Original Paper; Physics; Physics and Astronomy; Porosity; Properties of type I and type II superconductors; Strongly Correlated Systems; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Superconductivity; Superconductors; Yttrium
• ISSN: 1557-1939; 1557-1947
• DOI: 10.1007/s10948-012-1996-0

The comparison between YBa 2 Cu 3− x Ca x O δ and YBa 2 Cu 4− x Ca x O 8 superconductors substituted with Ca at the Cu-site was investigated. The concentration of Ca varied from x =0.00 to x =0.15. Resistivity and current density measurement (without magnetic field) were measured using four-probe method. The samples were characterized using X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). From the resistivity measurement, the critical temperature ( T c  zero ) in x =0.00 was 84 K for Y-123 and 83 K for Y-124 superconductor system. As the Ca concentration increased to x =0.15, both superconductor systems showed a decrease in value whereby 71 K for Y-123 and 74 K for Y-124. This was a result of the decrease in the hole concentration. Critical current density ( J c ) decreased with the further increment of Ca concentration owing to grain connectivity and an increase of porosity. At 50 K, J c decreased from 3.9790 A/cm 2 at x =0.00 to 3.5184 A/cm 2 at x =0.15 for Y-123, and from 3.6209 A/cm 2 at x =0.00 to 0.5243 A/cm 2 at x =0.15 for Y-124. The crystallographic crystal structure showed that both Y-123 and Y-124 superconductor systems exhibited an orthorhombic form. FESEM microscopy showed that the Y-123 sample had less porosity compared to Y-124 samples and the resulting Y-123 sample had a higher J c compared to the Y-124 sample.