Anisotropic mechanical behavior of gadolinia-doped ceria solid electrolytes under tensile loading

The electrolyte of solid oxide fuel cells is generally a ceramic material whose inherent brittleness greatly limits its application. Understanding the fracture mechanism of electrolyte materials is an important issue to be resolved. In this study, the anisotropic deformation behavior of gadolinia-doped ceria (GDC) solid electrolytes is investigated by using the molecular dynamics method. When GDC is subject to uniaxial tensile loading, different fracture mechanisms are found in different crystal orientations. In the [100], [21¯1¯] crystal stretching process, phase transformation from fluorite to rutile occurs, while, in the [110] crystal orientation, multiple phase transformations are observed between fluorite and rutile structure, demonstrating the good loading capacity by a stress-induced transformation toughening mechanism. There is no phase transformation in the [111] crystal orientation, which exhibits brittle cleavage fracture owing to electrostatic repulsion of adjacent oxygen ion layers. Finally, the two-sided effects of temperature and doping concentration on different fracture mechanisms are analyzed.