Recent development and application of mesocrystals

Mesocrystal structures can be applied to the active materials of lithium-ion batteries. The crystallinity, specific surface area, and exposed crystal face have potential for the improvement of their performance. The nanosized building blocks contribute to shorten the diffusion distance of lithium ions. The conductivity of ions and electrons can be improved by the single crystalline structure. The high surface area and porous interior are beneficial for the reversible stability at a high charge-discharge rate. 

As shown in Fig. 1, mesocrystal structures have the nanoscopic space between each nanocrystal. We have proposed that organic molecules can be introduced in the nanoscopic space of mesocrystal structures of biominerals and biomimetic materials. When the organic dye molecules were introduced in the nanospace, the photoluminescence was observed with excitation by UV light. Photochemical reactions, such as dimerization and isomerization, were achieved in the nanospace. Recently, we have shown the hierarchical replication of biominerals with organic polymers from nanoscopic to macroscopic scales (Fig. 26). After the 

Gilbert and coworkers recently reported on the low surface area of biominerals consisting of nanocrystals. Based on the measurements, the surface area of sea urchin spine is comparable to that of spacefilling macroscopic geologic calcite crystals. The mesoerystal struetures of biominerals are different from those of synthetic materials. They suggested that the low specific surface area is ascribed to the presence of ACC in the nanospace. In fact, organic molecules can be introduced in the nanospace from the solution or the liquid state. However, the gas for the measurement of the surface area is not introduced in the nanospace. The structures of the nanospace in mesocrystals remain unresolved problems. 

We adopted the prismatic layer of a bivalve shell as a model for in vitro repairing (Fig. 28). °° The prismatic layer is comprised of calcite prisms elongated in the c axis and an interprismatic organic framework. In the original prismatic layer, calcite polygonal columns 10-50 pm in diameter 

The partial regeneration of biominerals can be interpreted as the oriented growth of nanocrystals with the association of organic molecules. The epitaxial growth of mesocrystals leads to the in vitro repair of biominerals. Soluble organic molecules, such as glutamic acid and PAA, contribute to the formation of mesocrystals in the repaired part. When insoluble organic 

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