Transport critical current density in superconducting Y-358

In high temperature superconductors (HTS) flux pinning mechanism and critical current densities are highly related. We have synthesized and characterized bulk superconducting Y-358. By using FESEM the granular nature and distribution of grain dimensions have been studied. At zero magnetic field current voltage (IV) characteristics below the critical temperature (Tc) have been used to extract transport critical current density using an electric field (E) criterion. Possibility of the nonlinearity in IV has been explored. At T = 72.5 K, grain critical current density (J_cG) and total critical current density (J_c) are found to be ∼ 11.04 x 10⁴ A/cm² and 0.26 A/cm² respectively. Variations of Jc and JcG with temperature have been investigated. An exponential growth of J (T) and J_cG (T) has been observed. Role of number of superconducting planes and Josephson coupling between layers in controlling JcG has been studied in the phase transition region using coherence length and interlayer separations. (author)