Enhancing pinning ability by the addition of potassium niobate nanorods in YBCO superconductor

Abstract

In the current study, we have investigated the effect of adding potassium niobate (KNbO3) nanorods (NRs) in YBCO superconductor to improve flux pinning properties. The KNbO3-NRs are synthesized by hydrothermal method, and KNbO3-YBCO nanocomposites are prepared by incorporating variable amounts of the NRs in YBCO matrix by solid-state reaction method. X-ray diffraction (XRD) pattern confirmed the orthorhombic phase of YBCO, KNbO3-NRs, and KNbO3-YBCO nanocomposite samples. The morphology and composition of the YBCO, KNbO3, and KNbO3-YBCO nanocomposites are studied using field emission scanning electron microscopy (FESEM) and energy-dispersive x-ray spectroscopy (EDX). Magnetic measurements of KNbO3-YBCO nanocomposites are carried out at temperatures from 15 to 65 K under an external magnetic field from -7 to + 7 T. The value of critical temperature (TC0) in xKNbO3-YBCO nanocomposites showed no significant decrease from the TC0 value obtained for YBCO, indicating that inserting a modest amount of KNbO3-NRs into the YBCO matrix does not result in substantial changes in TC0. The critical current density (JC) showed an enhancement of ∼ 3.6 times in 0.5wt%KNbO3-YBCO nanocomposite compared to YBCO. Additionally, when the concentration of KNbO3-NRs in YBCO was raised, the critical current density (JC) decreased due to the accumulation of KNbO3-NRs at the interfaces between grain boundaries. The rate of JC decay decreases as the externally applied field increases for nanocomposite samples compared to YBCO, showing an improvement in the pinning properties of nanocomposites.