Iryna Polishchuk1

1, Materials Science and Engineering, Technion–Israel Institute of Technology, Haifa, , Israel

Composite materials usually exhibit the combined physical properties of their constituents. The result is a material that is superior to conventional monolithic materials. Advanced composites are used in a variety of industrial applications and therefore attract much scientific interest. Here we report on the formation of novel carbon-based nanocomposites via incorporation of graphene oxide (GO) into the crystal lattice of single crystals of calcite (1). Incorporation of a 2D organic material into single-crystal lattices has never before been reported. The resulting nanocomposites were characterized utilizing state of the art characterization techniques such as high-resolution synchrotron powder X-ray diffraction, electron microscopy, aberration corrected high resolution transmission electron microscopy, fluorescence microscopy and nanoindentation tests.
Our results show that GO sheets can indeed become incorporated into calcite single crystalline hosts, allowing for the fabrication of graphene-based composite materials with enhanced properties. A detailed analysis reveals a layered distribution of GO sheets entrapped within the calcite host. Moreover, the optical and mechanical properties of the calcite host are altered when a carbon-based nanomaterial is introduced into its lattice. Carbon-based calcite single crystals exhibit new optical properties: in contrast to pure calcite, the hybrid crystals become fluorescent and are spectroscopically characterized by the presence of three lifetimes, one of which is considerably longer than that observed for bare GO in solution. Nanoindentation tests demonstrated that relative to pure calcite the composite GO/calcite crystals exhibit lower elastic modulus and higher hardness.
The results of this study demonstrate that the incorporation of a 2D material within a 3D crystal lattice is not only feasible but can also lead to the formation of hybrid crystals exhibiting novel properties.

Di Giosia M, Polishchuk I, Weber E, Fermani S, Pasquini L, Pugno NM, Zerbetto F, Montalti M, Calvaresi M, Falini G and Pokroy B. Bioinspired nano-composite: 2D materials within a 3D lattice. Adv Funct Mater2016; 26:5569.