$Fe_{0.5}Cu_{0.5}(Ba_{1-x}Sr_{x})_2YCu_2O_{7+\delta}$ ($x$ = 0, 0.5 and 1) superconductors prepared by high pressure synthesis

TL;DR

This study successfully synthesized Fe-containing superconductors with varying compositions using high pressure methods, revealing that high pressure synthesis enhances superconductivity by increasing oxygen content and Fe atom redistribution, rather than secondary phases.

Contribution

It demonstrates a new synthesis approach for Fe-doped cuprate superconductors and clarifies the role of high pressure in inducing superconductivity.

Findings

Superconductivity is mainly induced by high pressure synthesis.

High pressure increases oxygen content and redistributes Fe atoms.

Superconductivity is not due to secondary phases.

Abstract

In this paper, the $Fe$-containing superconductors $Fe_{0.5}Cu_{0.5}Ba_2YCu_2O_{7+\delta}$, $Fe_{0.5}Cu_{0.5}BaSrYCu_2O_{7+\delta}$ and $Fe_{0.5}Cu_{0.5}Sr_2YCu_2O_{7+\delta}$ were successfully prepared by common solid-state reaction followed with a procedure of high pressure synthesis. The structural change and superconducting properties in $(Fe_xCu_{1-x})BaSrYCu_2O_{7+\delta}$ ($x$ = 0 $\sim$ 1.0) systems were also investigated. Annealing experiments indicate that the occurrence of superconductivity in $Fe_{0.5}Cu_{0.5}(Ba_{1-x}Sr_{x})_2YCu_2O_{7+\delta}$ ($x$ = 0, 0.5 and 1) systems is mainly induced by the procedure of high pressure synthesis, which causes the increase of oxygen content and the redistribution of $Fe$ atoms between $Cu(1)$ and $Cu(2)$ sites, but not from possible secondary phase of $YBa_2Cu_3O_{7-\delta}$, $YBaSrCu_3O_{7-\delta}$ or $YSr_2Cu_3O_{7-\delta}$ superconductors.