A novel non-catalytic synthesis method for zero- and two-dimensional B13C2nanostructures

Abstract

Boron carbide nanoparticles and nanoflakes represent nano-building blocks for complex hierarchical assembly of nanoscale structures that exhibit ideal mechanical robustness. These nano-building blocks were synthesized by simply changing the mixing ratio of the solid precursors to influence the saturation condition of the process. As such, the ability to tune the nanostructures of boron carbide was achieved by controlling the concentration of gaseous boron oxide in the process with no catalyst involved in the growing process. The phase of the resulting nanostructures were found to be B₁₃C₂, which is a much desired phase because its hardness of close to 60 GPa is twice as hard as B₄C. Nanoflakes were found to contain high degree of (101)-type twins with their boundaries likely to pass through the center of icosahedra in the structure. Nanoflakes with twinned microstructure are anticipated as a model nanostructure and can provide opportunities to fundamentally explore their mechanistic nature since twins have the potential in inhibiting the crack propagation, leading to toughening the materials.