Effect of Na doping on flux pinning of YBa1.9Na0.1Cu3O7-d

TL;DR

This study investigates how sodium doping affects flux pinning in YBa2Cu3O7 superconductors, revealing that Na doping reduces critical current density and pinning energy, thus negatively impacting flux pinning properties.

Contribution

The paper provides experimental evidence on the negative impact of Na doping on flux pinning and related properties in YBCO superconductors using melt-textured growth.

Findings

Na doping shifts the irreversibility line to lower temperatures.

Na doping decreases critical current density and pinning energy.

Na doping introduces a second peak in Jc(Hdc) curves and increases anisotropy.

Abstract

We have prepared Na-doped YBa2Cu3Oy (YBa1.9Na0.1Cu3Oy +40mol%Y211) (YBNCO) and Na-free YBa2Cu3Oy (YBCO) samples by the Melt-Textured Growth (MTG) method to study the effect of doped Na ion on flux pinning. The ac susceptibility curves (acs) as well as the hysteresis loops were measured for the samples. Then the effective pinning energy (U(T,Hdc,J)), irreversibility line (Hirr(T)) and critical current density (jc(Hdc)) were determined, where T, Hdc and J are temperature, dc magnetic field and current density, respectively. We found that, with Na doping, the Hirr(T) line shifted to lower temperature while the Jc(Hdc) and U(T,Hdc,J) became smaller. It indicates that the Na ions play a negative role in the flux pinning of YBCO. The appearance of the second peak in the Jc(Hdc) curves and the enhancement of anisotropy in YBNCO further support this finding.