Structural characterization of natural shell. a) Photographs of outside part of natural shell (left picture) shows attractive color and of inner part (right picture) shows the nacrous layer. b) SEM image of the cross section micro-structure of natural nacre c) Magnified SEM image of (b) shows the "brick-and-mortar" structure of natural nacre. d) Magnified SEM image of (c) shows the mineral bridges between neighboring aragonite platelets. Credit: Advanced Materials (2025). DOI: 10.1002/adma.202416535
Modern industry requires multi-dimensional performance design of protective structural materials. In nature, many organisms maintain the mechanical strength required for defense and achieve camouflage effects at the same time. Among them, nacre demonstrates a fracture toughness far beyond its constituent components due to the sophisticated multi-level microstructure. How to effectively apply this structural design to engineering material systems remains a challenge.
In a study published in , a research team led by Academician Yu Shuhong from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences reported a structure-function integrated design of nacre-mimetic alumina (Al2O3)-based (NMA) composites. This NMA composite material not only has unique color tunability and excellent wave transparency, but also achieves lightweight, high strength, high toughness, and outstanding impact resistance.
Researchers proposed a dual-oxide interface design strategy. By constructing mineral bridge structures between alumina micro-plates (MPs), the mechanical strength and toughness were significantly improved. By regulating the chemical composition of the assembled MP interface through solid-phase reactions, the controllable coloring was achieved.
Additionally, researchers prepared a new type of NMA composites through self-evaporation assembly and high-temperature sintering. It was found that the fracture toughness of this biomimetic composite was more than three times that of commercial alumina ceramic, and the absorbed impact energy reached more than four times that of commercial alumina ceramic.
Considering NMA composites' favorable structural conditions for transmission of electromagnetic (EM) waves, researchers proposed a new design for EM wave transmission. The wave-transmission became more efficient, which is due to the micron-scale wave-transmission channels formed by the layered ceramic framework and low-dielectric constant polymer and the optical axis vertical orientation of single-crystal aluminum oxide MPs.
The study realizes the synergistic enhancement of the mechanical properties and EM transmission performance, providing platforms for future applications in the field of aerospace, navigation, and electronics.
More information: Jun Pang et al, Mechanical Robust Nacre鈥怣imetic Composites with Designable Cryptic Coloration and Electromagnetic Wave鈥怲ransparent Performance, Advanced Materials (2025).
Journal information: Advanced Materials
Provided by University of Science and Technology of China
