Ultrahigh Recovery of Fracture Strength on Mismatched Fractured Amorphous Surfaces of Silicon Carbide

Abstract

Nanowires (NWs) have been envisioned as building blocks of nanotechnology and nanodevices. In this study, NWs were manipulated using a weasel hair, and fixed by conductive silver epoxy, eliminating the contaminations and damages induced by conventional beam depositions. The fracture strength of the amorphous silicon carbide was found to be 8.8 GPa, which was measured by in situ transmission electron microscopy nanomechanical testing, approaching the theoretical fracture limit. Here, we report that self-healing of mismatched fractured amorphous surfaces of brittle NWs was discovered. The fracture strength was found to be 5.6 GPa on the mismatched fractured surfaces, recovering 63.6% of that of pristine NWs. This is an ultrahigh recovery, due to the limits of reconstruction of dangling bonds on the fractured amorphous surfaces and the mismatched areas. Simulation by molecular dynamics showed fracture strength recovery of 65.9% on the mismatched fractured amorphous surfaces, which is in good agreement with the experimental results. Healing on the mismatched fractured amorphous surfaces is by reorganization of Si-C bonds forming Si-C and Si-Si bonds. The potential energy increases 2.6 eV in the reorganized Si-C bonds, and decreases by 3.2 and 1.9 eV, respectively, in the formed Si-C and Si-2 Si bonds. These findings provide insights for the reliability, design and fabrication of high performance NW-based devices, to avoid catastrophic failure working in harsh and extreme environments.

Bactericidal behavior of chemically exfoliated boron nitride nanosheets doped with zirconium

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Click chemical assembly and validation of bio-functionalized superparamagnetic hybrid microspheres

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Self-healing on mismatched fractured composite surfaces of SiC with a diameter of 180 nm

“…Recently, self-healing is confirmed on fractured surfaces of SiC with diameters of 87, 104 and 102 nm under vacuum without external interventions. 31,32 However, the self-healing occurred on pure crystalline or amorphous fractured surfaces, resulting in applications that are limited dramatically under the two extreme conditions. For example, SiC undergoes phase transformation under deformation, stress and ion irradiation, [13][14][15][16][17][18] forming an AAC composite structure.…”

“…32 It was predicted that self-healing could not be realized on fractured NWs with diameters more than 150 nm, on account of the big gap generated by the variation of height on the fractured rough surfaces. 31 This prediction is based on the fact that the larger the diameter, the rougher the surfaces generated on the fractured parts. Previous research studies demonstrate that rough surfaces have extreme difficulty in undergoing selfhealing, due to the big gap considerably impeding the contact of fractured surfaces.…”

“…For this reason, nonuniform NWs are used to conduct in situ TEM tensile tests, avoiding the fracture of several segments simultaneously. 32 For a uniform NW, a purely local amorphous phase in a single crystal is employed to carry out the self-healing, because of the lower fracture strength (8.8 GPa) 31 of the amorphous phase compared to that of the monocrystalline phase (13.4 GPa). 32 When the amorphous phase accounts for a lower volume in the AAC composite structure of SiC, it is difficult to conduct self-healing on mismatched fractured surfaces.…”