Molecular dynamics simulations of the deformation behavior of gadolinia-doped ceria solid electrolytes under tensile loading

Gadolinia-doped ceria (GDC) is a promising candidate electrolyte material for use in intermediate-temperature solid oxide fuel cells (IT-SOFCs). By doping gadolinia during the synthesis process, some oxygen vacancies are generated to promote ionic conductivity. However, the mechanical properties of GDC are severely attenuated by introduced point defects. In the current work, molecular dynamics (MD) simulations are carried out on the uniaxial tensile deformation process of GDC. The GDC is observed to undergo a stress-induced martensitic phase transformation from a fluorite structure to a rutile structure or its twin structure. It is found that the addition of point defects has a significant influence on the phase-transformation behavior of GDC, which limits the further deformation and the loading capacity of the material. The dopant-dependent tensile strength is also obtained and is observed to be consistent with reported experimental measurements.

► The deformation behavior of gadolinia-doped ceria under tensile loading was investigated. ► A martensitic transformation from a fluorite to a rutile or its twin structure was observed. ► A stress-induced pre-transformation occurs before martensitic nucleation. ► The oxygen vacancies can hinder the pre-transformation by disrupting the mechanism. ► The tensile strength shows a fluctuation trend, which accords with the experiments.