WEB Mechanical characterization of 3-D supercrystalline ceramic-organic nanocomposites
Supercrystalline ceramic-organic nanocomposites are a rising field that has multiple applications in advanced optical, electronic and biomedical materials. They consist of nanoparticles functionalized with organic ligands brought into periodic long-range ordered structures via self-assembly. They have been widely studied in the form of thin films and 2-D structures however when it comes to bulk nanocomposites and their mechanical properties there is a lack of data in the literature. Here in this study, the latter is addressed. Bulk supercrystalline materials are manufactured by colloidal self-assembly of functionalized iron oxide nanoparticles, subsequently pressed and heat-treated, which leads to an increase in the stiffness and hardness of the material by a factor of four to eight thanks to the crosslinking of the ligands of adjacent nanoparticles. The mechanical properties of the resulting supercrystalline nanocomposites are determined by nanoindentation and micro-bending and compression of FIBed samples. Additionally, the fracture toughness is measured with the indentation crack length method, notched microbars, and with a first-of-a-kind approach called energy method. The fracture surfaces are analyzed to explain emerging deformation behaviors.