Characteristics of lanthanum aluminate as an electrolyte in solid oxide fuel cell

Abstract

This research aimed to study the effect of Sr and Mg substitutions on the properties of LaAIO3 used as an electrolyte in solid oxide fuel cell. All compositions were synthesized by conventional mixing process of oxides and carbonate and sintered at 1500, 1550 and 1575℃. Phase, crystal structure and microstructure were carried out by XRD and SEM and the thermal expansion coefficient was determined by a dilatometer. The electrical conductivity as a function of temperature was investigated by AC impedance spectroscopy and DC four probe measurements. The XRD results revealed that the structure of undoped and Sr- and Mg- doped compositions appeared to be distorted from cubic. After sintering, second phases could be observed in all compositions. The SEM microstructure showed that with Sr-dopant, the average grain size of LaAIO3 decreased. The thermal expansion of all compositions increased as the amount of Sr and Mg increased. The electrical measurement revealed that the highest electrical conductivity of 301.06x10-3 S/cm at 1000℃ and 37.23x10-3 S/cm at 800℃ could be obtained from the composition of La0.9Sr0.1Al0.85Mg0.15O2.875.