Effects of calcium substitution on the superconducting properties of R(1-x)CaxBa2Cu3Oz (R=Eu, Gd, Er; 0=<x<=0.3)polycrystalline samples

TL;DR

This study investigates how calcium substitution affects the superconducting properties of polycrystalline R(1-x)CaxBa2Cu3Oz samples with R=Eu, Gd, Er, revealing dependencies on Ca content and R element type, and identifying optimal conditions for flux pinning.

Contribution

It provides new insights into how Ca substitution influences superconducting parameters and flux pinning, especially highlighting the Gd-based system's optimal properties.

Findings

Superconducting critical temperature varies with Ca content and R element.

Gd-based samples show the best combination of critical current and flux pinning.

Flux pinning is linked to R1+yBa2-yCu3Oz clusters in Gd samples.

Abstract

The influence of Ca substitution on the superconducting properties of polycrystalline R1-xCaxBa2Cu3Oz (R = Eu, Gd, Er; x=0; 0.2; 0.25 and 0.3) samples has been studied by X-ray powder diffraction, ac susceptibility and dc magnetization measurements. The superconducting parameters such as critical temperature, inter- and intra-granular critical current and flux pinning are found to be strongly dependent both on Ca content and type of R element. The best combination of these parameters is found for the system Gd1-xCaxBa2Cu3Oz forming R1+yBa2-yCu3Oz clusters. The level of overdoping and the type of intergrain connection, were found to be influenced by the R element and the Ca concentration. Flux pinning in Gd1-xCaxBa2Cu3Oz is connected with the presence of R1+yBa2-yCu3Oz clusters.