The Effect of Co-Doping at the A-Site on the Structure and Oxide Ion Conductivity in (Ba0.5-xSrx)La0.5InO3-δ: A Molecular Dynamics Study.

Kuk-Jin Hwang,Tae Shin,Seong-Min Jeong,Myung-Hyun Lee,Hae-Jin Hwang

doi:10.3390/ma12223739

Kuk-Jin Hwang, Tae Shin + Show 3 more

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https://doi.org/10.3390/ma12223739

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Abstract

A molecular dynamics simulation was used to investigate the structural and transport properties of a (Ba0.5−xSrx)La0.5InO3−δ (x = 0, 0.1, 0.2) oxygen ion conductor. Previous studies reported that the ionic conductivity of Ba-doped LaInO3 decreases because Ba dopant forms a narrow oxygen path in the lattice, which could hinder the diffusion of oxygen ions. In this study, we reveal the mechanism to improve ionic conductivity by Ba and Sr co-doping on an La site in LaInO3 perovskite oxide. The results show that the ionic conductivity of (Ba0.5−xSrx)La0.5InO3−δ increases with an increasing number of Sr ions because oxygen diffusion paths which contain Sr ions have a larger critical radius than those containing Ba ions. The radial distribution function (RDF) calculations show that the peak heights in compositions including Sr ions were lower and broadened, meaning that the oxygen ions moved easily into other oxygen sites.

Highlights

Ceramic ion conductors are important materials for application in electrochemical devices, such as solid oxide fuel cells (SOFCs), oxygen pumps, and oxygen sensors, due to their oxide ion conductivity and chemical and mechanical stability at high operating temperatures [1,2,3]
The aim of this study was to reveal the mechanism for improving ionic conductivity by Ba and Sr ions co-doping on an La site in LaInO3 using a structural investigation method and a molecular dynamics simulation
This study suggests that to achieve a high ionic conductivity in doped LaInO3, the critical radius should be = larger by the substitution of cations

Summary

Introduction

Ceramic ion conductors are important materials for application in electrochemical devices, such as solid oxide fuel cells (SOFCs), oxygen pumps, and oxygen sensors, due to their oxide ion conductivity and chemical and mechanical stability at high operating temperatures [1,2,3]. To achieve high ionic conductivity, oxygen ion conductors must have a large open space that allows a high level of point defect disorder and low migration enthalpy [4]. Some examples of such oxides are ZrO2 , CeO2 , Bi2 O3 based oxide with fluorite structure, LaGaO3 based perovskites, Bi4 V2 O11- and La2 Mo2 O9 -based derivatives, Ba2 In2 O5 derived perovskite, and brownmillerite such as phases and pyrochlores [5]. Fluorite-related structures such as yttria-stabilized zirconia (YSZ) show good performance as oxide ion conductors at high temperatures (~0.1 S·cm−1 at 1273 K). It is well known that the electrical conductivity of YSZ decreases to around 0.03 S·cm−1 at 1073 K [6]

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