Study of microstructure and magneto-transport properties in Bi1.6Pb0.4Sr2Ca3GdxCu4Oδ superconducting systems


Journal of Materials Science: Materials in Electronics, vol.29, no.19, pp.16157-16165, 2018 (SCI-Expanded) identifier


The role of Gd addition in the Bi1.6Pb0.4Sr2Ca3GdxCu4Oy (x = 0.0, 0.1, 0.2, 0.3 and 0.4) system was examined by X-ray powder diffraction, scanning electron microscopy, critical current density (Jc) and magneto-transport measurements. The samples were fabricated by the conventional solid state reaction method. The analysis showed that the critical temperature (Tc) and hole number (p) of the materials decreased while the room temperature resistances increased with the addition of Gd. The resistance–temperature dependence for the low-resistance regions of the transition can be determined by the thermally activated flux flow model. The upper critical field [Hc2(T)] values calculated by using this model decreased with the addition of Gd. Furthermore, it was observed that the activation energy (U0) decreased both with the increase in the amount of Gd and applied magnetic field. The degradation of the superconducting properties of the samples may be related to the alteration of the structural, electronic and magnetic properties of the materials depending on the presence of the Gd ions. As a result, the decrease in the number of holes and the magnetic properties of Gd ions are thought to be the fundamental reasons for the deterioration of the superconducting properties of the materials. It has been observed that Gd additions from the microstructure studies of the materials affected the surface morphology negatively.