  Advanced composites are used in a variety of industrial applications and
therefore attract much scientific interest. Here we describe the formation of
novel carbon-based nanocomposites via incorporation of graphene oxide into the
crystal lattice of single crystals of calcite. Incorporation of a 2D organic
material into single-crystal lattices has never before been reported. To
characterize the resulting nanocomposites we employed high-resolution
synchrotron powder X-ray diffraction, electron microscopy, transmission
electron microscopy, fluorescence microscopy, and nanoindentation tests.
Detailed analysis revealed a layered distribution of graphene oxide sheets
incorporated within the calcite host. Moreover, the optical and mechanical
properties of the calcite host were altered when a carbon-based nanomaterial
was introduced into its lattice. Compared to pure calcite, the composite
GO-calcite crystals exhibited lower elastic modulus and higher hardness. The
results of this study show that the incorporation of a 2D material within a 3D
crystal lattice is not only feasible but also can lead to the formation of
hybrid crystals exhibiting new properties.
