Effects of Fe-dopings through solid solution and grain-boundary segregation on the electrical properties of CeO2-based solid electrolyte

The 1 and 10 mol% Gd-doped ceria (1- and 10-GDC) solid solution powders were synthesized by co-precipitation method, then which were doped with 0.5 mol% Fe by the means of solid solution (SS) and preferred grain-boundary segregation (GBS), named as GDC-0.5Fe (SS) and (GBS), respectively. All the synthesized powders only show the CeO2 solid solution phase with grain sizes of 15.8 similar to 16.8 nm. Then, the corresponding GDC ceramics before and after Fe-doping were sintered at 800 A degrees C for 1 h. The sole ceria solid solution phase appears in all the sintered samples with grain sizes of 59.8 similar to 112 nm. The Fe doping through solid solution always leads to the decrement in the electrical conductivity of both 1- and 10-GDC samples, while that through controlled grain-boundary segregation results in the increment of 10-GDC sample. The ion transference numbers of 1- and 10-GDC-0.5Fe (GBS) samples are all above 0.95 in 300 similar to 650 A degrees C.