Structural and Electrical Properties of Niobium Doped Y<sub>0.6</sub>Gd<sub>0.4</sub>Ba<sub>2-x</sub>Nb<sub>x</sub>Cu<sub>3</sub>O<sub>7-y</sub> Superconductors

Abstract

Polycrystalline samples of Y 0.6 Gd 0.4 Ba 2-x Nb x Cu 3 O 7-y (YGBNCO) with different Nb contents (x = 0.05, 0.10, 0.15, 0.20, and 0.25) were prepared using the usual solid state reaction technique. The structure for all samples was characterized by XRD and SEM. The electrical properties were measured by the FPP method in the temperature range from 70 to 130 K. The lattice constant of b remains almost unchanged and a and c increases with the increase of Nb content with x ≤ 0.10. The zero resistance transition temperature and J c decrease with increasing Nb content. But superconductivity did not suppress. As the Nb content in the samples increases, it gives a diffused phase indicating a niobium perovskite phase and it is a small amount of unidentified phase.