Solid oxide cell (SOC) technology represents one of the most promising possibilities in the near future in terms of sustainable energy generation and storage. Indeed, these devices can directly convert the chemical energy that is stored in a wide range of fuels, into current electricity, with high efficiency and low emissions.

The major limits to their development are currently related to the high temperatures of use, which shorten their service life and increase production costs. Electrolyte materials, therefore, play a key role in determining both the SOC electrochemical mechanism and operating temperature, being determined by the nature and activation energy of the conduction process.

Hence, Perovskite-type materials such as BaCe_1-x-y-zZr_xY_yYb_zO_3−δ (BCZYYb) are very attractive due their unique dual–conductivity at intermediate temperature (450-600°C) as well as good thermo-chemical stability, coking resistance and sulphur tolerance. For this system the proton conduction process is activated at lower temperatures than the anion conduction process, making these new materials competitive as the single-conduction ones. Moreover, the mixed oxygen-ion and proton conductivity has been demonstrated to drastically improve the SOC performances, allowing numerous encouraging applications in multi-fuel supply cells, from hydrogen to hydrocarbons.

In this study we propose a comparison between chemical and solid-state synthesis methods to obtain BCZYYb electrolyte powders. Two different compositions were chosen, BaCe_0.7Zr_0.1Y_0.1Yb_0.1O_3−δ (BCZYYb7111) and BaCe_0.4Zr_0.4Y_0.1Yb_0.1O_3−δ (BCZYYb4411), as it is well known, the first to have higher conductivity value in standard condition, while the second present greater chemical stability in CO2-rich atmospheres. Sol-gel and co-precipitation chemical methods were explored as synthetic methods starting from metal nitrates precursors. On the other hand, the influence of ball milling and planetary milling processes was evaluated in solid-state reactions starting from metal oxides/carbonates. Through meticulous microstructural and morphological characterisations, it was possible to determine how the diverse synthesis parameters can influence the structure and purity of the target phase. Finally, the powders obtained has been employed to produce high density electrolyte suitable for solid oxide cell applications.