Abstract
This study systematically investigates the thermal decomposition, densification behaviour, microstructural evolution , electronic structure, ionic conductivity, and electrochemical performance of Bi and Cu co-doped GDC (2B1C) powders. Thermal expansion and sintering analysis reveal that the 2B1C powders exhibit excellent low-temperature sinterability, achieving near-full densification with a relative density of 98.6 % at 750 °C, and further reaching 98.7 % at 850 °C, which is significantly lower than the sintering temperature of conventional GDC. XRD and SEM results confirm high purity and well-formed crystalline structures with advanced densification. XPS and Raman analyses reveal that doping modulates the defect chemistry and enhances oxygen vacancy concentration. Impedance spectroscopy shows that 2B1C-2 achieves the highest ionic conductivity of 2.12× 10^-2 S·cm −1 at 750 °C. Moreover, in a practical SOC cell configuration, the YSZ-supported cell with a 2B1C barrier layer demonstrates capable electrochemical performance, achieving a maximum power density of 235.1 mW/cm 2 at 850 °C. Overall, Bi and Cu co-doping significantly lowers the sintering temperature and enhances ionic conductivity, making 2B1C a promising electrolyte candidate for metal-supported solid oxide cells (SOCs) at reduced processing temperatures.