Effect of sintering aids on the conductivity of BaCeo.9Ln_(0.1)O_(3-δ)

摘要

Polycrystalline powders of BaCe_(0.9)Ln_(0.1)O_(3-δ) (Ln - La, Nd, Sm, Gd, Yb, Tb and Y) have been prepared using a freeze-drying precursor route at 1000 C. In order to decrease the densification temperature, different sintering aids (e.g. Co, Zn, Ni, Fe and Cu) were added by mixing the polycrystalline powders with a nitrate solution containing these metals. This allows obtaining dense ceramics at temperatures as low as 1000°C, when compared to samples without sintering aids at 1400 C. The effect of aid content and sintering temperature on the microstructure and electrical conductivity were investigated by scanning electron microscopy and impedance spectroscopy. The addition of small amounts of transition metals does not produce observable structural changes by conventional X-ray powder diffraction. However, the bulk and total conductivities decrease when compared to samples without transition metals. Zn seems to be the most effective sintering element for BaCe_(0.9)Ln_(0.1)O_(3-δ) electrolytes because it does not cause significant changes in the ionic and electronic conductivities.