Reduction annealing effects on the crystal structure of $T^{\prime}$-type La$_{1.8}$Eu$_{0.2}$CuO$_{4+\alpha-\delta}$

TL;DR

This study investigates how reduction annealing affects the crystal structure of La$_{1.8}$Eu$_{0.2}$CuO$_{4+eta- ext{delta}}$ using neutron diffraction, revealing structural similarities with Pr$_{2}$CuO$_{4+eta- ext{delta}}$ despite superconductivity only appearing in the Eu-doped sample.

Contribution

It provides detailed neutron diffraction analysis of La$_{1.8}$Eu$_{0.2}$CuO$_{4+eta- ext{delta}}$ before and after reduction, highlighting structural similarities with related compounds and the emergence of superconductivity.

Findings

Structural parameters are similar to Pr$_{2}$CuO$_{4+eta- ext{delta}}$.

Oxygen positions are unaffected by reduction annealing.

Superconductivity appears only in Eu-doped samples.

Abstract

We performed neutron powder diffraction measurements on the as-sintered (AS) and oxygen-reduced (OR) La$_{1.8}$Eu$_{0.2}$CuO$_{4+\alpha-\delta}$ (LECO). The structural parameters for oxygens in AS and OR samples refined by the Rietveld analysis are almost identical to those of the reference system, Pr$_{2}$CuO$_{4+\alpha-\delta}$. Thus, the two systems are comparable in terms of the structural changes in oxygens due to the annealing, although superconductivity appears only in LECO.