Production and characterisation of strontium and magnesium doped lanthanum-gallium oxide (LSGM) ceramics

摘要

Strontium and magnesium doped lanthanum-gallium oxide (LSGM) ceramics exhibit high oxygen ionic conductivity at medium temperatures (800℃) as compared to other materials such as yttrium stabilised zirconia. Due to this property, they are candidates to be used as electrolyte materials in solid oxide fuel cells (SOFC).rnIn this study, La_(0.80)Sr_(0.20)Ga_(0.83)Mg_(0.17)O_(3-δ) and La_(0.90)Sr_(0.10)Ga_(0.80)Mg_(0.20)O_(3-δ) powders were prepared from metal-nitrate starting materials by a Pcchini type sol-gel process. Obtained powders were sintered at 1430℃ for 24 hours in air. Powder X-ray diffraction and scanning electron microscopy analysis were performed on the powders and sintered ceramics and densities of the sintered ceramics were measured. Ceramics having single phase perovskite structure were produced with theoretical densities higher than 97%.rnLSGM ceramics were subjected to impedance spectroscopy analysis at 300℃, after coating with platinum. No grain boundary contribution was observed on the impedance of the ceramics. Ionic conductivities of the samples were measured in 400 1200℃ range. At 800℃, the highest ionic conductivity value was measured as 0.14 S/cm, which was obtained in the La_(0.80)Sr_(0.20)Ga_(0.83)Mg_(0.17)O_(3-δ) composition.