Role of Aniline Addition in Structural and Superconducting Properties of MgB2 Bulk Superconductor

In this study, the structural and superconducting properties of aniline-added MgB2 superconductors were investigated by X-ray diffraction (XRD), thermal analysis techniques, and ac susceptibility measurements. The amount of aniline was changed from 0 to 1 mol%. Phase analysis and lattice parameters were determined from XRD measurements. X-ray diffraction analysis indicates that the main phase is MgB2 and that there is a small amount of Mg as the secondary phase in aniline-added samples. According to the determination of lattice parameters, it is seen that the addition of aniline does not give a proper distribution with the contribution amount of a and c lattice parameters. From DSC curves, two exothermic peaks and one endothermic peak were observed in all samples. Pure and aniline-added samples were found to be dependent on the magnetic field in the ac susceptibility measurements, and the superconducting transition temperature (Tc) was found to decrease to lower temperatures due to an increase in the amount of aniline. It has been determined that changes in the in-phase (χ′) and out-of-phase (χ″) components of the ac susceptibility by increasing the aniline amount have weakened the MgB2 phase structure and thus cause changes in the pinning mechanism. In addition, ac losses of all the samples were calculated under external fields ranging from 160 to 1280 A/m and at 25 K.