Electrical and mechanical characterization by Instrumented Indentation technique of La0.85Sr0.15Ga0.8Mg0.2O3-d electrolytes for SOFCs

Abstract

La0.85Sr0.15Ga0.8Mg0.2O3−δ pellets obtained by the polymeric organic complex solution method, isostatic pressing and sintering at 1350 °C have been electrical and mechanically studied. Electrical measurements evidenced reasonable ionic conductivities (0.01 S cm−1 at 800 °C), which were comparable to those reported for the La1−xSrxGa1−yMgyO3−δ prepared by other synthesis methods. On the other hand, the mechanical properties (elastic modulus, E and hardness, H) have been determined at micro/nanometric scale using the instrumented indentation technique. While E did not vary significantly with the increasing indentation depth (h), H values strongly decreased with the indentation depth up to 500 nm. For h > 500 nm, both mechanical properties remained almost constant, thus obtaining E = 271 ± 6 GPa and H = 13.2 ± 0.4 GPa. Finally, the residual imprints and fracture mechanisms have been observed by atomic force microscopy (AFM).