Structural and Magnetic Studies on La2-xDyxCa2xBa2Cu4+2xOz Type Superconducting Oxides

TL;DR

This study investigates how doping with dysprosium and calcium affects the structure and superconducting properties of La2-xDyxCa2xBa2Cu4+2xOz compounds, revealing increased Tc and flux pinning with higher dopant levels.

Contribution

It provides detailed structural and superconducting property analysis of La-2125 type oxides with varying Dy and Ca doping, highlighting calcium's role in inducing superconductivity.

Findings

Superconducting transition temperature (Tc) increases with dopant concentration, reaching 75 K at x=0.5.

All samples exhibit tetragonal La-123 type structure confirmed by neutron diffraction.

Flux pinning force and critical current density improve with higher doping levels.

Abstract

The La-2125 type La2-xDyxCa2xBa2Cu4+2xOz (0.1 < x < 0.5; LDBO) compounds have been synthesized and studied for their structural and superconducting properties by room temperature neutron diffraction, high field dc magnetization, four-probe resistivity and iodometric double titration. The Rietveld analysis of the neutron diffraction data reveals tetragonal structure for all the samples, which crystallizes into La-123 type tetragonal structure in P4/mmm space group. Iodometric double titrations were performed to determine the oxygen content values and calculate mobile charge carrier (holes) density. The superconducting transition temperatures (Tc) increases from ~ 20 K for x = 0.1 to a maximum of 75 K for x = 0.5. Flux pinning force (Fp) and critical current density (Jc), calculated from the low temperature hysteresis loops, also increases with increasing dopant concentration. The paper presents the studies on structure and superconducting properties of all LDBO compounds in light of the role of calcium in inducing superconductivity in the tetragonal non-superconducting oxide.