Partial disclinations

Wit, R. de

doi:10.1088/0022-3719/5/5/004

Cited by 131 publications

(71 citation statements)

References 10 publications

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“…The latter can also be qualitatively understood as we think that a part of the stress could be relieved by the core of the nanowire which could be coherently relaxed as in a star-disclination model. 6 Experimentally, this is consistent with the observed contrast difference in the lattice image near the center of the nanowire compared with that of the rest of T4 ͓Fig. 1͑g͔͒.…”

supporting

confidence: 83%

“…In FTNWs with small diameters, elastic energy consideration has lead to either coherent lattice transformation ͑homogeneous strain͒ 5 or a stardisclination distortion ͑inhomogeneous strain͒. 6 Above a critical diameter, we expect that the nanowires either revert back to a single crystalline structure or adopt an incoherently relaxed structure involving extended defects 4 such as dislocations. 7 Kinetics is expected to blur but not change this picture much.…”

mentioning

confidence: 99%

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Incoherent structural relaxation of fivefold twinned nanowires

Jiang

Zhang

et al. 2008

Applied Physics Letters

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Boron carbide nanowires with a fivefold twinned structure have been shown to have regular spaced microtwin lamellas localized in one of the crystalline segments. This defect structure is interpreted as incoherent structural relaxation to relieve the angular excess. A structural model, in terms of a disclination core surrounded by a small angle grain boundary with an intersecting microtwin lamella pair structure, has been proposed and strain analyses suggest it could be a common phenomena for nanowires with large angular mismatch and small twinning formation energy.

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confidence: 83%

mentioning

confidence: 99%

Incoherent structural relaxation of fivefold twinned nanowires

Jiang

Zhang

et al. 2008

Applied Physics Letters

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“…The gap can be accommodated by straining the atomic lattice. If the strain is uniformly distributed in the decahedron, a disclination will form at the center of the decahedral particle [36]. That is just the case of the FePt nanocrystal shown in Fig.…”

Section: Structure Of Multiply Twined Nanocrystalsmentioning

confidence: 98%

Shapes, multiple twins and surface structures of monodisperse FePt magnetic nanocrystals

Sun²,

2002

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Shapes, surface atomic arrangement and structural evolution induced by annealing of monodisperse FePt nanocrystals, synthesized by a solution phase chemical procedure, have been studied by high-resolution transmission electron microscopy. The as-synthesized FePt nanocrystals display dominantly a truncated octahedron shape enclosed by flat {1 0 0}, stepped {1 1 1} and zig-zag {1 1 0} facets. The Marks decahedron FePt nanocrystals and the icosahedron based multiply twined FePt nanocrystals are identified in the as-synthesized particles. An improved structural model has been proposed for the multiply twined nanocrystals. After annealing, the {1 1 0} facets disappear and a regular cuboctahedron becomes the dominant shape. Surfaces of the FePt nanocrystals show no reconstruction but with some atomic steps and kinks. Ó

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“…Thus, some form of internal distortion must be incorporated. Some examples of these are a homogenous elastic strain 29 , an inhomogeneous strain 28,30 , dislocations 23,28,31,32 or a crystal structure modification. 28,33,34 The icosahedron comprises 20 grains, each of which is a not-quite-regular tetrahedron in which each unit cell has a rhombohedral distortion that (in the ideal case) has magnitude = 0.0261 (see Equation 3.1 for the definition of ).…”

Section: Multiply Twinned Silver Nanoparticlesmentioning

confidence: 99%

Size-dependent structure of silver nanoparticles under high pressure

Koski

2008

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Professor A Paul Alivisatos, ChairSilver noble metal nanoparticles, that have a diameter less than 10 nm, often possess multiply twinned grains allowing them to adopt shapes and atomic structures not observed in bulk materials. The properties exhibited by particles with multiply-twinned polycrystalline structures are often far different from those of single-crystalline particles and from the bulk. I will present experimental evidence that silver nanoparticles < 10 nm undergo a reversible structural transformation under hydrostatic pressures up to 10 GPa.Results for nanoparticles in the intermediate size range of 5 to 10 nm suggest a reversible linear pressure-dependent rhombohedral distortion which has not been previously observed in bulk silver. I propose a mechanism for this transition that considers the bond-length distribution in idealized multiply twinned icosahedral particles. At smaller sizes, results for 3.9 nm silver nanoparticles suggest a reversible linear orthorhombic distortion that continuously varies with hydrostatic pressure to 8GPa. This distortion is interpreted in the 2 context of idealized decahedral particles.In addition, given these size-dependent measurements of silver nanoparticle compression with pressure, we have constructed a pressure calibration curve. Encapsulating these silver nanoparticles in hollow metal oxide nanospheres then allows us to measure the pressure inside a nanoshell using x-ray diffraction. We demonstrate the measurement of pressure gradients across nanoshells and show that these nanoshells have maximum resolved shear strengths on the order of 500 MPa to 1GPa.Professor A Paul Alivisatos Dissertation Committee Chair i

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Partial disclinations

Cited by 131 publications

References 10 publications

Incoherent structural relaxation of fivefold twinned nanowires

Incoherent structural relaxation of fivefold twinned nanowires

Shapes, multiple twins and surface structures of monodisperse FePt magnetic nanocrystals

Size-dependent structure of silver nanoparticles under high pressure

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