Abstract
The development of high-temperature superconductor (HTS) YBa2Cu3O7~δ (Y123) bulks in industrial applications were established years ago. It is one of the developments that currently attracts great attention especially in transportation, superconductor cables and wires. This study is focused on the preparation of the Y123 bulk superconductors by the thermal treatment method due to the promising ways to develop high-quality Y123 superconductors with its simplicity, low cost, and relatively low reaction temperature used during the process. Y123 were added with graphene nanoparticles (x = (0.0–1.0) wt.%). Samples were then characterized by X-ray diffraction (XRD) analysis, field-emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), and alternating current susceptibility (ACS). It was found that Y123 confirmed that the majority of phases in all the XRD patterns was the orthorhombic crystal structure and the Pmmm space group with secondary phases belonged to Y2Ba1Cu1O5 (Y211). The highest Tc obtained when graphene nanoparticles were added in the Y123 sample was x = 1.0 wt.%, followed by x = 0.5 wt.% with 92.64 and 92.59 K, respectively. From the microstructure analysis, the average grain size significantly decreased to 4.754 µm at x = 0.5 wt.%. The addition of graphene nanoparticles had disturbed the grain growth of Y123, affecting the superconducting properties of the samples. On the other hand, the intergranular critical current density, Jcm, was found to increase with graphene nanoparticle addition and had the highest value at x = 1.0 wt.%, indicating that graphene nanoparticles acted as pinning centers in the Y123 matrix.
Highlights
The discovery of superconductivity in YBa2 Cu3 O7~δ (Y123) compounds have attracted significant attention around the world due to its high critical temperature (Tc ), the ability to be cooled to the superconducting state by the cheap LN2 and their promising ability in numerous technological applications, including in real life such as in magnetic levitation transportations system and high power transmission cables [1,2,3]
1.0 wt.% have been successfully prepared by the thermal treatment method
X-ray diffraction (XRD) analysis using Rietveld refinement showed that Y123 major phase was found with orthorhombic structures and the secondary phase of Y211 in all samples, even though the XRD analysis cannot detect the presence of graphene nanoparticles
Summary
The discovery of superconductivity in YBa2 Cu3 O7~δ (Y123) compounds have attracted significant attention around the world due to its high critical temperature (Tc ), the ability to be cooled to the superconducting state by the cheap LN2 and their promising ability in numerous technological applications, including in real life such as in magnetic levitation transportations system and high power transmission cables [1,2,3]. The intrinsic properties of Y123 polycrystalline compounds, such as weak links at the grain boundary, have limited its performance in applications, especially at temperatures of 20–30 K and the applied magnetic field [4]. It is very challenging to raise their properties to the level due to some limitations. This problem has been attributed to the lower J c , which caused the degradation of its superconducting properties instead. The high superconducting performance of Y123 can be achieved by enhancing flux pinning in the Y123 system by ensuring good condition during the processing of Y123 bulks to obtain good quality and ultimate performances
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