Microstructural and Superconducting Properties of YBa_2Cu_{3-x}Co_xO_{7-\delta} System

TL;DR

This study investigates how cobalt doping affects the microstructure and superconducting properties of YBa2Cu3O7-δ, revealing that Co increases critical current density while decreasing transition temperature, with microstructural defects playing a key role.

Contribution

It provides new insights into the effects of cobalt substitution on the microstructure and superconducting parameters of YBa2Cu3O7-δ, including detailed microstructural analysis.

Findings

Critical current density increases with Co doping.

Transition temperature decreases with Co doping.

Microstructural defects contribute to flux pinning.

Abstract

Bulk superconductor samples of YBa2Cu3-xCoxO7-{\delta} with x = 0, 0.01, 0.03, 0.05 are synthesized by solid-state reaction route. Both x-ray diffraction and electron microscopy have been employed to study the phase identification, intergrowths, dislocations and the local structure of these samples. Transition temperature of the samples has been determined by four probe resistivity measurements. The x-ray diffraction patterns indicate that the gross structure/ phase of YBa2Cu3-xCoxO7-{\delta} do not change with the substitution of Co up to x=0.05. The zero resistance critical transition temperature [Tc(R=0)] is found to decrease and critical current density (Jc) increases with the increased concentration of cobalt in the compound. The Jc enhancement for the cobalt doped samples may be resulting due to flux pinning from some defects such as planar defects, stacking faults and micro defects (twin, domains etc.) and the rapid suppression in Tc may be due to the cooper pair breaking and the hole filling in the CuO2 planes.