Inspired by sea urchins and coccoliths, which produce inorganic skeletons from amorphous calcium carbonate (acc) in the environment, researchers have demonstrated the ability to make minerals or ceramics composed of a single chemical compound from acc nanoparticles, using pressure-driven fusion. The findings represent an advance over traditional ceramic sintering methods and could prove useful in constructing other materials made of a single chemical compound - or monoliths - from temperature-sensitive biominerals and biomaterials. Inorganic materials are a staple of modern technology. However, synthesizing inorganic monoliths is challenging because current sintering techniques can destroy the material's continuity and limit its mechanical strength. This is particularly true for acc, which, despite being a relatively hard material, is sensitive to heating and tends to form rigid crystalline structures when compressed. In nature, organisms have developed ways to produce flexible and strong inorganic exoskeletons using acc particles. Here, Zhao Mu and colleagues show similar acc monoliths can be manufactured through compression. This is achieved by regulating the amounts of structurally bound water and external pressure of acc particles in such a way that particle boundaries fuse without triggering sample-wide crystallization, producing transparent monoliths with mechanical strength similar to that of single-crystal calcite. According to the authors, this process is largely analogous to the biomineralization of skeletons using numerous amorphous particles and could be used to enable large-scale and efficient manufacturing of continuously structured inorganic monoliths.
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Journal
Science