Study and optimization of the synthesis routine of the single phase YBaCo2O6-δ double perovskite

A L Sednev,D S Tsvetkov

doi:10.15826/chimtech/2017.4.3.03

Abstract

The chemical interaction of YCoO3-δ and BaCoO3-δ with formation of double perovskite was studied depending on temperature and oxygen partial pressure. The stability of YCoO3 was shown to have а crucial influence on the kinetics and mechanism of YBaCo2O6-δ formation. It was found that at 1000 °C in air, i.e. under conditions when YCoO3 is unstable, the double perovskite YBaCo2O6-δ is formed much slower compared to the pure oxygen atmosphere where YCoO3 is stable at the same temperature. Thus controlling YCoO3 stability was shown to be the factor of key importance for optimal preparation of the YBaCo2O6-δ single phase.

Highlights

Complex oxide YBaCo2O6–δ with double perovskite structure has been extensively investigated in recent years as a promising material for oxygen membranes [1, 2] and solid oxide fuel cells (SOFCs) [3, 6, 7, 9, 12] due to high mixed ionic-electronic conductivity [12] and moderate thermal expansion comparable to that of the state-of-the art SOFC electrolytes [3]
YBaCo2O6–δ is unstable in air at temperatures between 800 and 850 °C [13] and decomposes to mixture of the simple perovskites YCoO3–δ and BaCoO3–δ, which are more thermody
The presence of these impurities is a consequence of instability of the YCoO3, which decomposes in air at T ≥ 900 °C with formation of Y2O3 and CoO [11,12,13, 22, 23]

Summary

Introduction

Complex oxide YBaCo2O6–δ with double perovskite structure has been extensively investigated in recent years as a promising material for oxygen membranes [1, 2] and solid oxide fuel cells (SOFCs) [3, 6, 7, 9, 12] due to high mixed ionic-electronic conductivity [12] and moderate thermal expansion comparable to that of the state-of-the art SOFC electrolytes [3]. Taking into account that synthesis of YBaCo2O6–δ proceeds through the formanamically stable under these conditions. This significantly impedes obtaining a single phase material. A synthesis routine, which could be provided the single phase YBaCo2O6–δ obtaining, has not been discussed in literature so far. The main aim of the current work was to study a formation of the YBaCo2O6–δ double perovskite at 900 and 1000 °C in different gas atmospheres in order to optimize its synthesis routine

Objectives

Results

Conclusion