The nanoscale strength of ultra nano crystalline diamond

Aim of this paper is the estimation of the still unknown ultrananocrystalline diamond nanoscale strength. In spite of its measured strength at the microscale, of similar to 4 GPa, for a hypothetical nanowire with specified geometry (10 x 10 x 100 nm(3)) we have deduced a tremendously higher tensile strength, of similar to 23 GPa, as well as a bending strength of similar to 30 GlPa. A fractal exponent of similar to 2.5 and a Weibull modulus of similar to 10 are also derived. Such results are shown to be compatible with a theoretical estimation of the ideal strength, deduced as similar to 52 GPa by applying Quantized Fracture Mechanics, assuming the fracture quantum coincident with a grain size of similar to 3 nm. Doped materials are also treated.