Effects of Substituting Calcium for Yttrium on the Superconducting Properties of YBa2Cu3Oz Bulk Samples

TL;DR

This study investigates how substituting calcium for yttrium in YBa2Cu3Oz affects its superconducting properties, revealing optimal doping levels that enhance grain boundary transport and induce bulk pinning effects.

Contribution

It provides systematic analysis of calcium doping effects on superconductivity and microstructure in YBa2Cu3Oz, identifying optimal doping for improved properties.

Findings

Optimal doping at x=0.3 enhances grain boundary transport.

Superconducting transition temperature decreases to 85 K with doping.

Bulk pinning and nonlinear effects appear at high doping levels.

Abstract

We report systematic studies of AC magnetic susceptibility and transport properties of Y(1-x)Ca(x)Ba2Cu3Oz bulk samples with 0\leq x\leq 0.4. Single phase materials, reduction of carrier concentration and decrease of Tc to 85 K were obtained at doping levels up to 20%. For Y0.7Ca0.3Ba2Cu3Oz sample the improvement of grains boundary transport and screening capabilities has been observed as a result of the optimal ratio between carrier concentration and impurity phase BaCuO2 presence. The appearence of bulk pinning and nonlinear effects starting at the highest temperature were detected also.