Look for efficient Pr–Ni based SOCs oxygen electrodes in the Ruddlesden - Popper series: preliminary thermal stability studies focused on PrNiO3-δ and (Pr, La)4Ni3O10+δ

The present work investigates the thermal stability of Pr–Ni based nickelates belonging to the Ruddlesden-Popper (RP) series, specifically Pr4Ni3O10+δ, La4Ni3O10+δ, La3PrNi3O10+δ (n = 3), and PrNiO3-δ (n = ∞), as promising oxygen electrode materials for solid oxide cells (SOCs). A detailed preliminary study is therefore essential to determine the optimal conditions, particularly temperature and oxygen partial pressure (pO2), required for the successful synthesis, sintering, and application of these materials as electrodes. Thermogravimetric analysis (TGA) and X-ray diffraction (XRD) are employed to study their phase stability and decomposition behaviour under various atmospheres (argon, air, and oxygen). The results show that PrNiO3-δ has limited thermal stability, decomposing above 1040 °C in oxygen, while the other RP phases demonstrate greater stability, particularly Pr4Ni3O10+δ, which remains stable up to 1120 °C under oxygen. The substitution of La by Pr further improves the stability of the RP phases. Long-term aging experiments at 600–800 °C confirm that all materials maintain their phase integrity under air for up to three months. This study provides essential insights into optimizing synthesis and sintering conditions for these materials, supporting their application in high-temperature SOC devices.