Improving the electrical properties of Er-doped CeO2: effect of sintering aids CaO, MgO, and TiO2 on conductivity

This research reports the synthesis, characterization, and electrical properties of the systems EryCe1-yO2-delta (y = 0.05, 0.1, and 0.15), and the effect of the incorporation of sintering aids (2 wt.% of CaO, MgO, and TiO2) on the electrical properties of the composition Er0.1Ce0.9O1.95, to be used as ceramic solid electrolytes in low-temperature solid oxide fuel cells (LT-SOFC). All EryCe1-yO2-delta samples were obtained by mechanochemistry (20 h of milling) and characterized by XRD. The morphology of the pure sintered compositions and with the incorporation of sintering aids (sintered at 1200 degrees C) was evaluated by FE-SEM. Electrical properties as a function of temperature (200-650 degrees C) and frequency (100 Hz-1 MHz) were evaluated by impedance spectroscopy. It reveals an increase of bulk ionic conductivity for higher contents of Er, as the number of oxygen vacancies increases. The higher value of conductivity (6.7 x 10(-3) S cm(-1)) at 650 degrees C was for the composition Er0.15Ce0.85O1.925, while the ionic conductivity of Er0.1Ce0.9O1.95 at 650 degrees C increased from 2.68 x 10(-3) S cm(-1) to a maximum of 1.54 x 10(-2) S cm(-1) with the incorporation of CaO as additive. These improvements in bulk ionic conductivities can contribute to the development of more efficient electrolytes for the LT-SOFC technology.