Max-Planck-Institute of Colloids and Interfaces, Research Campus Golm, Am Mühlenberg 1, D-14424 Potsdam, Germany.
Proc Natl Acad Sci U S A. 2012 Mar 6;109(10):3699-704. doi: 10.1073/pnas.1109243109. Epub 2012 Feb 16.
Structuring over many length scales is a design strategy widely used in Nature to create materials with unique functional properties. We here present a comprehensive analysis of an adult sea urchin spine, and in revealing a complex, hierarchical structure, show how Nature fabricates a material which diffracts as a single crystal of calcite and yet fractures as a glassy material. Each spine comprises a highly oriented array of Mg-calcite nanocrystals in which amorphous regions and macromolecules are embedded. It is postulated that this mesocrystalline structure forms via the crystallization of a dense array of amorphous calcium carbonate (ACC) precursor particles. A residual surface layer of ACC and/or macromolecules remains around the nanoparticle units which creates the mesocrystal structure and contributes to the conchoidal fracture behavior. Nature's demonstration of how crystallization of an amorphous precursor phase can create a crystalline material with remarkable properties therefore provides inspiration for a novel approach to the design and synthesis of synthetic composite materials.
多层次结构是自然界中广泛用于创造具有独特功能特性的材料的一种设计策略。我们在这里对成年海胆刺进行了全面分析，揭示了一种复杂的层次结构，展示了自然界如何制造出一种既能像方解石单晶那样衍射又能像玻璃材料那样断裂的材料。每个刺都包含高度取向的 Mg-方解石纳米晶体阵列，其中嵌入了非晶区和大分子。据推测，这种准晶结构是通过密集排列的无定形碳酸钙 (ACC) 前体颗粒的结晶形成的。纳米颗粒单元周围残留的 ACC 和/或大分子形成了准晶结构，并有助于贝壳状断裂行为。自然界展示了无定形前体相的结晶如何能够创造出具有显著性能的结晶材料，因此为设计和合成新型合成复合材料提供了灵感。
