Electrical Conductivity of La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-D/La_1.55Sr_0.45Ga₃O_7+D Composite Electrolyte

Abstract

Doped lanthanum gallate constitutes a family of solid electrolytes with high ionic conductivity, wide electrolytic domain and good chemical stability. The combination of their properties turns some compounds of this family, promising candidates for application in solid oxide fuel cells operating at intermediate temperatures. In this work, La0.9Sr0.1Ga0.8Mg0.2O3-δ - x La1.55Sr0.45Ga3O7+δ, with x = 0, 1 and 5 wt.% were investigated aiming to obtain a composite solid electrolyte with optimized properties compared to the parent material. Composite electrolytes were prepared by solid state reaction method and evaluated for densification, phase content and microstructure. Electrical conductivity measurements were carried out as a function of temperature and oxygen partial pressure. Increase on densification and microstructural homogeneity were obtained with increasing fraction of the melillite phase. The electrical conductivity determined by impedance spectroscopy revealed a decrease of the grain resistivity for increasing amounts of La1.55Sr0.45Ga3O7+δ.