From Al2O3 microplatelets to bioinspired structures on synthesis, magnetic assembly, and mechanical performance

Al 2 O 3 microplatelets provide versatile building blocks for architectured materials because their high aspect ratio, stiffness, and anisotropic geometry enable the construction of hierarchical structures inspired by natural materials such as nacre. Despite substantial progress in platelet synthesis, field-assisted assembly, additive manufacturing, and interface engineering, the relationships linking Al 2 O 3 hierarchical structure and mechanical performance remain fragmented. This review critically examines these relationships from a processing–structure–interface–property perspective. We first compare solid-, hydrothermal-, molten-salt-, and gas-phase routes for synthesizing Al 2 O 3 microplatelets, emphasizing the trade-offs among morphology control, aspect ratio, surface chemistry, scalability, and downstream processability. We then analyze magnetically assisted assembly and 3D printing by considering the coupled effects of magnetic torque, viscous resistance, gravitational effects, platelet geometry, Al 2 O 3 loading, and rotation frequency, and propose a processing-window framework for predictive orientation control. The mechanical performance of bioinspired Al 2 O 3 architectures is subsequently discussed in terms of the coupled roles of platelet aspect ratio, orientation, interfacial properties, mineral-bridge connectivity, and hierarchical architecture in controlling crack deflection, sliding, pull-out, bridging, and energy dissipation. Finally, key knowledge gaps are identified in platelet synthesis, magnetic 3D printing, alignment optimization with high solid-loading, quantitative interface design, and multifunctional applications. On this basis, a roadmap is proposed toward predictive design and scalable manufacturing of bioinspired Al 2 O 3 structures.