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Magneto transport and magnetization are studied in graphene oxide (GO)-doped YBa2Cu3O7-δ (YBCO) high-temperature superconductor. The samples were prepared by sol-gel method with different weight percentage (0, 0.3, 0.5 wt.%) of GO. The transition temperature of GO-doped samples did not change in comparison with the pure YBCO. However, SEM images show that the GO doping reduces the grain average diameter, which results in an enhancement (up to a factor of ~ 2) of the critical current density and of the flux pinning force in the presence of different applied magnetic fields. [ABSTRACT FROM AUTHOR]

In this work, bulk graphene-doped YBa 2 Cu 3 O 7-δ (YBCO) high-temperature superconductor samples were prepared with composition of YBCO + x wt.% graphene nanoplatelets (G) (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0). The X-ray diffraction patterns show the YBCO orthorhombic phase in all the samples. The SEM images show good grain connectivity between YBCO grains in graphene-doped samples. Furthermore, the broadening of resistivity under applied magnetic fields up to 9T and thermally activated flux creep in the mixed state were studied using Arrhenius plots. The activation energy U 0 (H) increased with graphene doping results in better flux pinning and higher critical current densities. Moreover, improvement in the critical temperature (T C), upper critical field (μ 0 H C2) and the irreversibility field (μ 0 H irr) were observed in graphene-doped samples as compared to the pure YBCO sample. [ABSTRACT FROM AUTHOR]

Abstract: The effects of carbon nano-tubes (CNTs) on the crystal structure and superconducting properties of YBa2Cu3O7− δ (Y-123) compound were studied. Samples were synthesized using standard solid-state reaction technique by adding CNT up to 1wt% and X-ray diffraction data confirm the single phase orthorhombic structure for all the samples. Current–voltage measurements in magnetic fields up to 9T were used to study the pinning energy UJ and critical current density J c as a function of magnetic field at fixed temperature. We find that while T c does not change much with the CNT doping (91–92K), both UJ and J c increase systematically up to 0.7wt% CNT doping in a broad magnetic field ranges between 0.1 and 9T and J c in the 0.7wt% 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 J c increase. [Copyright &y& Elsevier]