The Mechanical Behaviors in Oxides: Beyond Brittleness

Oxide materials are traditionally perceived as intrinsically brittle due to their strong covalent and ionic bonds, which hinder plastic deformation and limit their applicability in emerging technologies such as flexible and wearable electronics. Over the past two decades, various strategies have broken through this paradigm, endowing crystalline oxides with unconventional mechanical properties, such as ultra-flexibility, super-elasticity, and enhanced ductility. These breakthroughs have uncovered a diverse range of distinct deformation mechanisms, encompassing size effects, mobile point defects, dislocation activities, domain switching, phase transitions, and the role of engineered artificial structures. In this review, we provide a comprehensive synthesis of the fundamental principles governing these behaviors across different dimensions of oxide nanostructures (0D, 1D, 2D, and 3D). At the same time, the most commonly used mechanical characterization techniques for each dimension are combined to explore how the dynamical process of each mechanism is influenced by mechanical loading modes, such as in situ tensile, compressive, or bending tests. Finally, we outline the future directions and challenges in this field, with an emphasis on the design of oxide materials for next-generation flexible electronics and other advanced applications.