Probing the long-term thermal stability mechanism of multi-rare-earth oxide-doped zirconia for solid oxide fuel cell electrolyte

The insufficient long-term thermal stability of 8 mol% yttria-stabilized zirconia (8YSZ) is caused by the formation and growth of the short-range ordered structure phase (t'' phase). This has limited the feasibility of utilizing this material as a solid electrolyte in solid oxide fuel cells (SOFCs). In this work, the long-term thermal stability of doped zirconia is improved by a multi-rare-earth oxide doping strategy. This strategy leads to lattice distortion and high dislocation density, causing an increase in migration energy (E_m), and the association energy (E_ass) is lowered. Consequently, the generation of the t'' phase is limited, and ionic conductivity does not significantly decrease during annealing. This work offers a new strategy for controlling the lattice distortion in electrolyte materials by regulating the radius and the content of dopants to realize a synergistic improvement in long-term thermal stability and ionic conductivity.