Improved microstructure and sintering temperature of bismuth nano-doped GDC powders synthesized by direct sol-gel combustion

To improve the microstructural and electrochemical properties of Gadolinium-doped ceria (GDC) electrolytes, materials co-doped ceria with bismuth oxide (1–5 mol%) have been successfully prepared in a one-step sol-gel combustion synthetic route. Sol-gel combustion facilitates molecular mixing of the precursors and substitution of the large Bi³⁺ cations into the fluorite structure, considerably reducing the sintering temperature. Adding Bi₂O₃ as a dopant increases the GDC densification to above 99.7% and reduces its traditional sintering temperature by 300 °C. Impedance analyses show that the addition of bismuth enhances the conductivity (3.1∙10⁻²−1.7∙10⁻¹ S·cm⁻¹ in the temperature range 600–800 °C) and improves the performance of the solid electrolyte in intermediate-temperature solid oxide fuel cells.