Increase of critical current density with doping carbon nano-tubes in YBa2Cu3O7-δ

• Published in: Physica. C, Superconductivity Vol. 469; no. 1; pp. 55 - 59
• Main Authors: DADRAS, S, LIU, Y, CHAR, Y. S, DAADMEHR, V, KIM, K. H
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 2009
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Critical currents; Effects of crystal defects, doping and substitution; Exact sciences and technology; Physics; Properties of type I and type II superconductors; Superconductivity; Transition temperature variations; YBa2Cu3O7-δ; Critical current density; Scanning electron microscopy; 74.25.Sv; Impurity density; Superconducting transitions; Doping; Magnetic field effects; Carbon nanotubes; 74.72.Bk; XRD; Carbon nano-tube doping; Solid state reaction; 74.62.Dh; High-Tc superconductors; Orthorhombic lattices; IV characteristic; Barium Copper Yttrium Oxides Mixed; 61.48.De
• ISSN: 0921-4534; 1873-2143
• DOI: 10.1016/j.physc.2008.11.004

The effects of carbon nano-tubes (CNTs) on the crystal structure and superconducting properties of YBa2Cu3O7-delta (Y-123) compound were studied. Samples were synthesized using standard solid-state reaction technique by adding CNT up to 1 wt% and X-ray diffraction data confirm the single phase orthorhombic structure for all the samples. Current-voltage measurements in magnetic fields up to 9 T were used to study the pinning energy UJ and critical current density Jc as a function of magnetic field at fixed temperature. We find that while Tc does not change much with the CNT doping (91-92 K), both UJ and Jc increase systematically up to 0.7 wt% CNT doping in a broad magnetic field ranges between 0.1 and 9 T and Jc in the 0.7 wt% CNT doped sample is at least 10 times larger than that of the pure Y-123. The scanning electron microscope image shows that CNTs are forming an electrical-network between grains. These observations suggest that the CNT addition to the Y-123-compounds improve the electrical connection between superconducting grains to result in the Jc increase.