Influence of phase segregation on the bulk and grain boundary conductivity of LSGM electrolytes

Electrolytes based on La1 − xSrxGa0.8Mg0.2O3 − δ (LSGM) are difficult to synthesise as single phase materials and secondary phases of LaSrGa3O7 and LaSrGaO4 are usually found at temperatures as high as 1400 °C. Dense LSGM ceramics with different amounts of these impurities were prepared from freeze-dried powders. These ceramics were studied by impedance spectroscopy to evaluate the influence of phase segregation on the bulk and grain boundary contributions to the ionic conductivity. The bulk and specific grain boundary conductivities of dense LSGM samples resulted to be nearly independent on the fraction of impurities. Furthermore, the ionic and electronic conductivities are not seriously affected by the presence of minor secondary phases.