Crystal phase, electrical properties, and solid oxide fuel cell electrolyte application of scandia-stabilized zirconia doped with rare earth elements

Abstract

ZrO2–10 ​mol% Sc2O3 (10ScSZ) has attracted attention as an electrolyte material for solid oxide fuel cells owing to its high conductivity. However, the phase transition between cubic and rhombohedral occurs in the range 500–600 ​°C, resulting in its rapid decrease in conductivity below 500 ​°C. In this study, we determined the elements that can eliminate phase transition in the range 500–600 ​°C for 10ScSZ to realize high conductivity for all temperature regions. Rare elements were incorporated to 10ScSZ. X-ray diffraction and conductivity measurements were used to confirm the occurrence of phase transition. The results noted that the addition of La, Ce, Pr, Nd, Sm, Eu, Gd, and Tb improved the conductivity of 10ScSZ below 500 ​°C, unlike that with the addition of Dy, Y, Ho, Er, Tm, Yb, Lu, and Sc. Further, although the addition of Ce to 10ScSZ was considered a solution, Nd and Sm were also noted to be effective additives.