Influence of Yttria-Stabilized Zirconia on Microstructure and Electrical Properties of Doped Lanthanum Gallate

Talita Gishitomi Fujimoto,Shirley Leite Reis,Eliana Navarro Dos Santos Muccillo

doi:10.1590/1980-5373-mr-2019-0043

Talita Gishitomi Fujimoto, Shirley Leite Reis + Show 1 more

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https://doi.org/10.1590/1980-5373-mr-2019-0043

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Abstract

Lanthanum gallate with partial substitutions for strontium and magnesium shows higher ionic conductivity than traditional ionic conductors such as yttria-stabilized zirconia (8YSZ), and has been considered for application as solid electrolyte and electrode in Solid Oxide Fuel Cells operating at intermediate temperatures (500-700oC). Parallel to the development of new solid electrolytes, improvement of the already known electrolytes has been one goal. In this work, the effects of adding 8YSZ to La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM), on the microstructure and electrical performance were investigated. Compound electrolytes consisting of up to 20 wt.% 8YSZ were prepared by solid state reactions. Sintered pellets with up to 10 wt.% 8YSZ achieved near full density after sintering at 1450oC and reduction in the fraction of impurity phases. Addition of 8YSZ promoted grain growth to LSGM. The higher ionic conductivity was obtained for 1 wt.% 8YSZ addition with slight decrease of the apparent activation energy.

Highlights

Oxide-ion conductors with perovskite structure based on doped lanthanum gallate find application as solid electrolyte and electrodes in Solid Oxide Fuel Cells (SOFCs)
Since the pioneering works of Ishihara[3] and Feng[4], ceramic conductors consisting of lanthanum gallate with partial substitutions for strontium and magnesium in the A- and B-sites, respectively, of the perovskite structure (La1xSrxGa1-yMgyO3-δ, with 0.1 ≤ x,y ≤ 0.2) have been thoroughly investigated, due to their high ionic conductivity along with wide electrolytic domain, as described in recent reviews[5,6]
The addition of 1 wt.% 8YSZ to LSGM resulted in a small increase of the bulk conductivity of LSGM

Summary

Introduction

Oxide-ion conductors with perovskite structure based on doped lanthanum gallate find application as solid electrolyte and electrodes in Solid Oxide Fuel Cells (SOFCs) These electrochemical devices have received considerable attention as clean-energy production systems, with several advantages, such as low noise, fuel flexibility, low emissions, high efficiency and cell scalability, compared to conventional energy conversion engines[1,2]. The need to improve the physical properties of these ceramic solid electrolytes has led to the investigation of more complex systems constituted by two solid electrolytes (compound or composite electrolytes). In this context, few studies may be found related to doped lanthanum gallates.

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