Abstract: As a natural armor, nacre evolved excellent mechanical properties. It has long been thought that the superior toughness of nacre derives from its brick-and-mortar structure, while its basic component-individual aragonite tablet, has not assume vital mechanical functions. However, recent investigations discovered that individual aragonite tablet exhibits characteristics of toughness, which may correlate with its nanostructure inside. Therefore, investigating the tablet′s nanostructure and unrevealing its structure-function relationships can shed additional light on the design and fabrication of high-performance artificial composites. In the present study, nanostructure and fracture behavior of individual aragonite tablet were investigated by using TEM techniques. Results showed that though diffracting as a single crystal, the tablet contains enormous intracrystalline organics inside. TEM observation of damaged tablets suggested that intracrystalline organics regulate the fracture mode of the tablet to a large extent. By synergistic effect of crack deflection, crack blunting and intracrystalline-organic deformation, the energy dissipation efficiency of individual aragonite tablet are remarkably promoted.

Key words: nacre, aragonite tablet, nanostructure, fracture behavior