Quantifying the defect-dominated size effect of fracture strain in single crystalline ZnO nanowires

He, Mo Rigen; Xiao, Pan; Zhao, Jiong; Dai, Sheng; Fang, Ke; Zhu, Jing

doi:10.1063/1.3594655

Cited by 17 publications

(24 citation statements)

References 27 publications

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“…17,18,41,42 It seems more fundamental to correlate fracture strain with (surface) defects instead of commonly used fracture strength, so as to eliminate the contribution of Young's modulus. 43 This argument is likely also applicable to ductile NWs such as the Ag NWs where yield strain can be correlated with side surface area.…”

Section: Resultsmentioning

confidence: 99%

Size effects on elasticity, yielding, and fracture of silver nanowires:In situexperiments

et al. 2012

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This paper reports the first quantitative measurement of a full spectrum of mechanical properties of five-fold twinned silver (Ag) nanowires (NWs) including Young's modulus, yield strength and ultimate tensile strength. In situ tensile testing of Ag NWs with diameters between 34 and 130 nm was carried out inside a scanning electron microscope (SEM). Young's modulus, yield strength and ultimate tensile strength all increased as the NW diameter decreased. The maximum yield strength in our tests was found to be 2.64 GPa, which is about 50 times the bulk value and close to the theoretical value of Ag in the <110> orientation. The size effect in the yield strength is attributed to the increase in the Young's modulus. Yield strain scales reasonably well with the NW surface area, which reveals that yielding of Ag NWs is due to dislocation nucleation from surface sources. Pronounced strain hardening was observed for most NWs in our study. The strain hardening, which has not previously been reported for NWs, is mainly attributed to the presence of internal twin boundaries. KEYWORDSfive-fold twin, size effect, Young's modulus, yield strength, ultimate tensile strength, strain hardening

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Section: Resultsmentioning

confidence: 99%

Size effects on elasticity, yielding, and fracture of silver nanowires:In situexperiments

et al. 2012

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“…Mechanical properties of wurzite ZnO NWs [17][18][19][20][21][22][23][24] or nanobelts (NBs) [25][26] are investigated under uniaxial tensile stress, [17][18][19][20] compressive and shear stress, 21 bending stress, 20,[23][24][25] or dynamic mechanical resonance. 22,26 Also, high-resolution TEM observation of strain-free ZnO NW surface revealed ZnO (10-10) m surface reconstruction with a radial contraction up to ε aa = -0.061 at surface to a depth of t Surf = 1.3 nm.…”

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confidence: 99%

Band-Gap Deformation Potential and Elasticity Limit of Semiconductor Free-Standing Nanorods Characterized in Situ by Scanning Electron Microscope–Cathodoluminescence Nanospectroscopy

et al. 2015

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Modern field-effect transistors or laser diodes take advantages of band-edge structures engineered by large uniaxial strain εzz, available up to an elasticity limit at a rate of band-gap deformation potential azz (= dEg/dεzz). However, contrary to aP values under hydrostatic pressure, there is no quantitative consensus on azz values under uniaxial tensile, compressive, and bending stress. This makes band-edge engineering inefficient. Here we propose SEM-cathodoluminescence nanospectroscopy under in situ nanomanipulation (Nanoprobe-CL). An apex of a c-axis-oriented free-standing ZnO nanorod (NR) is deflected by point-loading of bending stress, where local uniaxial strain (εcc = r/R) and its gradient across a NR (dεcc/dr = R(-1)) are controlled by a NR local curvature (R(-1)). The NR elasticity limit is evaluated sequentially (εcc = 0.04) from SEM observation of a NR bending deformation cycle. An electron beam is focused on several spots crossing a bent NR, and at each spot the local Eg is evaluated from near-band-edge CL emission energy. Uniaxial acc (= dEg/dεcc) is evaluated at regulated surface depth, and the impact of R(-1) on observed acc is investigated. The acc converges with -1.7 eV to the R(-1) = 0 limit, whereas it quenches with increasing R(-1), which is attributed to free-exciton drift under transversal band-gap gradient. Surface-sensitive CL measurements suggest that a discrepancy from bulk acc = -4 eV may originate from strain relaxation at the side surface under uniaxial stress. The nanoprobe-CL technique reveals an Eg(εij) response to specific strain tensor εij (i, j = x, y, z) and strain-gradient effects on a minority carrier population, enabling simulations and strain-dependent measurements of nanodevices with various structures.

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“…The MD simulations have proven that vacancies can lower strain at the elastic limit of wurtzite ZnO NWs to 4%. This value falls in the middle of experimental tests, 2%-7% [21]. On the contrary, surface contamination is the reason to raise fracture strain.…”

Section: Large Dispersion Of Fracture Strain Of Wurtzite Zno Nwsmentioning

confidence: 99%

“…Taking the wurtzite to tetragonal phase transformation in ZnO NWs as an example, the initial wurtzite structured NWs yields 6.5%-10.0% strain at the elastic limit [19,20]. These values fall at the middle of experimentally measured fracture strain, 2%-15%, of wurtzite structured ZnO NWs [19,[21][22][23]. After phase transformation, fracture strain reaches to 17%-20% [19,20].…”

Section: Introductionmentioning

confidence: 98%

“…One is the necessary requirement permitting the wurtzite to tetragonal phase transformation. The other is a reasonable interpretation of the large dispersion in fracture strain, 2%-15%, of wurtzite structured NWs [19,[21][22][23]. Motivated by these two contradictions, we performed systematic MD simulations on the tensile deformation of ZnO NWs in this paper.…”

Section: Introductionmentioning

confidence: 99%

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On the wurtzite to tetragonal phase transformation in ZnO nanowires

et al. 2017

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Dynamic behaviour of silicon carbide nanowires under high and extreme strain rates: a molecular dynamics study H Tsuzuki, J P Rino and P S Branicio There is a long standing contradiction on the tensile response of zinc oxide nanowires between theoretical prediction and experimental observations. Although it is proposed that there is a ductile behavior dominated by phase transformation, only an elastic deformation and brittle fracture was witnessed in experiments. Using molecular dynamics simulations, we clarified that, as the lateral dimension of zinc oxide nanowires increases to a critical value, an unambiguous ductile-to-brittle transition occurs. The critical value increases with decreasing the strain rate. Factors including planar defects and surface contamination induce brittle fracture prior to the initiation of phase transformation. These findings are consistent with previous atomistic standpoints and experimental results.

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Quantifying the defect-dominated size effect of fracture strain in single crystalline ZnO nanowires

Cited by 17 publications

References 27 publications

Size effects on elasticity, yielding, and fracture of silver nanowires:In situexperiments

Size effects on elasticity, yielding, and fracture of silver nanowires:In situexperiments

Band-Gap Deformation Potential and Elasticity Limit of Semiconductor Free-Standing Nanorods Characterized in Situ by Scanning Electron Microscope–Cathodoluminescence Nanospectroscopy

On the wurtzite to tetragonal phase transformation in ZnO nanowires

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