Multiscale Elasticity of 3D Boron Carbonitride Foam for Tunable Mechanical Resisting Devices

Boron carbonitride (BCN) foam is a three-dimensional material with a hierarchical structure, which has promising potential due to its semiconducting properties and high surface area. However, the lack of understanding of its elastic properties impedes its large-scale integration into advanced applications. We grew BCN foam samples with different atomic compositions and studied their microscopic- and macroscopic-scale mechanics, which revealed that samples with high concentrations of carbon have lower elastic resistance across different scales (i.e., lower Young’s moduli). While the microscopic elasticity is dominated by interlayer interactions, the macroscopic elasticity is also strongly influenced by the buckling and fracturing of the three-dimensional structure of the BCN foam, and thus, the macroscopic Young’s moduli are lower than the microscopic ones. Our findings shed light on the mechanism that underlies the multiscale mechanics of BCN foam and pave the path toward its integration into tunable mechanical resisting devices such as flexible electronic devices and resonators.