Hierarchical and intersectional microstructure of Graceful Fig shell

A Graceful Fig shell' microstructures are observed with a scanning electronic microscope (SEM). It shows that the shell is a kind of natural hierarchical bioceramic composite. The shell is composed of parallel aragonite-layers and each aragonite layer consists of thin aragonite sheets. Furthermore, each thin aragonite sheet is composed of lesser nano-aragonite fibers. It is also found that the aragonite fibers in arbitrary two adjacent aragonite-layers compose a kind of intersectional microstructure. The maximum pullout energy of the intersectional microstructure is investigated and compared to that of conventional parallel microstructure. It shows that the maximum pullout energy of the intersectional microstructure is markedly larger than that of the parallel microstructure. The larger the intersectional angle of the intersectional microstructure is, the more the maximum pullout energy of the intersectional microstructure will increase, compared to that of the parallel microstructure, which is experimentally validated.