Physical characterization of composites based on yttria-stabilized zirconia and doped lanthanum gallate

This work reports a systematic study on the microstructure, electrical conductivity, and nanoindentation of 8 mol% yttria-stabilized zirconia (8YSZ), La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-δ (LSGM) in both pure form and as composites. The main purpose was to evaluate the effects of the minor phase on the properties of the composite materials. Commercial 8YSZ was the major phase. Pure LSGM and composites consisting of 1, 10, and 20 wt.% LSGM were prepared by the solid-state reaction method. Sintering experiments were carried out from 1200°C to 1450°C. The temperature of maximum shrinkage decreased with increasing LSGM content. The average grain size of the composites was dependent on the relative proportion of the minor phase. Interface reactions occurr during sintering. Electrical conductivity of the composites was found to be lower compared to that of 8YSZ. The hardness showed no significant variation with the minor phase content, although a beneficial effect on the elastic modulus was noted for composites containing 10 wt.% LSGM.