Electrical conductivity studies on the LSGM–CGO composite electrolytes

The composite electrolytes x mol% La0.8Sr0.2Ga0.8Mg0.2O3−δ (LSGM)–(100 − x) mol% Ce0.9Gd0.1O1.95 (CGO), where x = 0, 10, 20 and 50, were synthesized via a mechanical milling followed by a solid state reaction method. Powder X-ray diffraction patterns confirmed the presence of major phases of LSGM and CGO in the composites sintered at 1450 °C for 10 h. A dense grain morphology was recognized from the scanning electron microscopy images of the polished surface of the sintered pellets. The composite of 10 mol% LSGM–CGO (LC10-90) showed an improved electrical conductivity compared with a pristine CGO (LC0-100) electrolyte. The composites electrolytes with increasing concentration of LSGM above 10 mol% in the CGO matrix exhibited a lowering of electrical conductivity. On the other hand, the homogenously dispersed LSGM phase in the CGO matrix was effective to expand the electrolytic domain region toward low oxygen partial pressures (PO2) compared with the pristine CGO electrolyte.