Investigation of the properties of carbon-base nanostructures doped YBa2Cu3O7−δ high temperature superconductor

In this research, we have investigated the effects of three samples of carbon-base nanostructures (carbon nanoparticles, carbon nanotubes and silicon carbide nanoparticles) doping on the properties of Y1Ba2Cu3O7−δ (YBCO) high temperature superconductor. The pure and doped YBCO samples were synthesized by sol-gel method and characterized by resistivity versus temperature (ρ-T), current versus voltage (I-V), through X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis. The results confirmed that for all the samples, the orthorhombic phase of YBCO compound is formed. We found that the pinning energy and critical current density of samples increase by adding carbon nanostructures to YBCO compound. Also critical temperature is improved by adding carbon nanotubes to YBCO compound, while it does not change much for carbon and silicon carbide nanoparticles doped compounds. Furthermore, the samples were characterized by UV-vis spectroscopy in 300 K and the band gap of the samples was determined. We found that the carbon nanotubes doping decreases YBCO band gap in normal state from 1.90 eV to 1.68 eV, while carbon and SiC nanoparticles doping increases it to 2.20 and 3.37 eV respectively.