Synthesis and characterization of IT-electrolyte with perovskite structure La 0.8Sr 0.2Ga 0.85Mg 0.15O 3− δ by glycine–nitrate combustion method

Abstract

The intermediate-temperature electrolyte with perovskite-type La 0.8Sr 0.2Ga 0.85Mg 0.15O 3−δ (LSGM) was synthesized using glycine–nitrate combustion method. The formation process of the LSGM phase was investigated using DTA–TGA and XRD, and the thermal and electrical properties of the sintered samples were studied by thermal expansion and ac impedance technology. The research results show that the formation process of the LSGM phase suffered several different reaction stages. The perovskite phase was formed essentially at a sintering temperature of 1200 °C. The stable perovskite phase was formed completely after a sintering temperature of 1400 °C. The sinterability shows that the sintering temperature of the sample, which was synthesized by glycine–nitrate combustion method, is at least 100 °C lower than that of the conventional solid state method that was reported previously. The thermal expansion coefficient of the LSGM is somewhat higher than that of the YSZ. Impedance spectra indicate that the grain boundary resistance of the LSGM synthesized by glycine–nitrate combustion method is smaller. The conductivity of sample sintered at 1500 °C is higher than that at 1550 °C. The conductivity of a sample is 7.8×10 −2 S cm −1 at 850 °C. The thermal analysis shows that the LSGM is relatively stable over an intermediate temperature range of 500–800 °C.