Modification of Magnetic and Electrical Properties of Bi,Pb-2223 Superconductors by Nano-Sized Eu Substitution

In the current paper, the effect of nano Eu particle (80 nm) substitution (x = 0.00, 0,025, 0.050, 0.1 and 0.15) in the Bi1.7Pb0.3Sr2Ca1Cu1.75Na0.25Oy on the structural, morphological, magnetic and superconductivity properties was investigated. The solid-state reaction method was used for producing the ceramic samples. The X-ray diffraction (XRD) analysis shows that the Bi-2223 phase with a tetragonal structure is the main phase structure in the ceramic samples. A flaky plate structure separated by grain boundaries has been observed in the scanning electron microscope (SEM). It was found that the grain sizes expanded and the inter-grain bonding increased when nano-sized Eu is added in the host structure. In magnetic hysteresis (M-H) measurements, diamagnetic behaviour, which is characteristic of the Bi-2223 superconductor phase, was observed in all samples. The sample with the best diamagnetic behaviour was substituted with Eu nano particle at a rate of x = 0.1, resulting in an increase in the hysteresis field with the formation of intergranular bonds. Based on M-H measurements performed at temperatures of 15 K and 25 K, the samples’ critical current density (Jc) was determined using the Bean model. The highest critical current density value was calculated in the sample substituted with nano-sized Eu at x = 0.1 rate as a result of improving intergranular connections. Flux pinning forces (Fp) were determined from Jc and B values. Nano-sized Eu particles at a ratio of x = 0.1 improved the pinning forces by acting as flux pinning centres.