| 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 ∼4 GPa, for a hypothetical nanowire with specified geometry (10x10x100 nm3) we have deduced a tremendously higher tensile strength, of ∼23 GPa, as well as a bending strength of ∼30 GPa. A fractal exponent of ∼2.5 and a Weibull modulus of ∼10 are also derived. Such results are shown to be compatible with a theoretical estimation of the ideal strength, deduced as ∼52 GPa by applying Quantized Fracture Mechanics, assuming the fracture quantum coincident with a grain size of ∼3 nm. Doped materials are also treated. |
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