Promising solid electrolyte material for an IT-SOFC: Crystal structure of the cerium gadolinium holmium oxide Ce₀.₈Gd₀.₁Ho₀.₁O₁.₉ between 295 and 1023 K

The crystal structure of Ce₀.₈Gd₀.₁Ho₀.₁O₁.₉ (cerium gadolinium holmium oxide) has been determined from powder X-ray diffraction data. This is a promising material for application as a solid electrolyte for intermediateerature solid oxide fuel cells (IT-SOFCs). Nanoparticles were prepared using a novel sodium alginate sol-gel method, where the sodium ion was exchanged with ions of interest and, after washing, the gel was calcined at 723'K in air. The crystallographic features of Gd and Ho co-doped cerium oxide were investigated around the desired operating temperatures of IT-SOFCs, i.e. 573 ≤ T ≤ 1023 K. We find that the crystal structure is a stable fluorite structure with the space group Fmm in the entire temperature range. In addition, the trend in lattice parameters shows that there is a monotonic increase with increasing temperature.