Size dependence of nanostructures: Impact of bond order deficiency

Sun, Chang Q.

doi:10.1016/j.progsolidstchem.2006.03.001

Cited by 825 publications

(792 citation statements)

References 673 publications

(820 reference statements)

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“…The atomic structure of nanocrystalline materials differs from that in the bulk due to relaxation phenomena [1]. The unit-cell volume compression is common for metal nanoparticles [2,3], whereas its expansion occurs in most nanosized metal-oxides [4,5].…”

Section: Introductionmentioning

confidence: 99%

Local structure relaxation in nanosized tungstates

Anspoks

Kalinko

Timoshenko

et al. 2014

Solid State Communications

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Section: Introductionmentioning

confidence: 99%

Local structure relaxation in nanosized tungstates

Anspoks

Kalinko

Timoshenko

et al. 2014

Solid State Communications

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“…At elevated temperatures, this exchange may allow for the formation of stable mixed metal-carbon nanoparticles that have a reduced density of host metal atoms but still retain the bulk crystal structure of the host. For example, a drastic reduction in the vacancy formation energy and in the activation energy of diffusion, shown consistently in calculations for small particles [36][37][38][39][40][41][42], could give rise to a net outdiffusion of host atoms and lead to large concentrations of vacancies, which in combination with a solute, such as carbon, could form vacancy-interstitial complexes that may be stable at the nanoscale. If such effects indeed occur, they may be quite prevalent in transition metal particles used for the synthesis of nanostructured carbon allotropes or in catalytic chemistry.…”

mentioning

confidence: 99%

Giant carbon solubility in Au nanoparticles

Sutter

2011

J Mater Sci

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Variable temperature transmission electron microscopy of individual 5 nm Au nanoparticles shows a striking increase in the particle size on raising the temperature from room temperature to 500°C in the presence of carbon from amorphous carbon support. Using the assembly of ordered graphene shells on the surface of individual nanoparticles at elevated temperatures-and the high pressures induced by such shells-as an experimental tool to study the origins of this swelling, we find that the volume increase is associated with the uptake of carbon to concentrations exceeding the bulk solubility by more than four orders of magnitude. The formation of stable metalcarbon nanostructures that have no bulk equivalent may have important implications on the functional properties of metal nanoparticles.The interaction of carbon with transition metals is key to processes for synthesizing the known sp 2 bonded carbon allotropes-fullerenes, nanotubes, and graphene-all of which are materials showing extraordinary properties and enormous potential for applications.Graphene, a planar two-dimensional honeycomb lattice of sp 2 bonded carbon atoms [1] Typically, transition metals catalytically dissociate hydrocarbons at their surfaces to set free carbon adatoms, which can be absorbed into the bulk at high temperature and segregate to the surface on subsequent cooling to form sp 2 -bonded structures. Planar graphene is synthesized by this process on bulk crystals or thin films of transition metals, such as Ru [16][17][18], Pt [19], Ir [20], and Ni [21], which can take up carbon into interstitial sites with solubilities up to a few atomic percent. Carbon nanostructures, such as fullerenes [22][23][24][25] are synthesized over transition metal (Fe, Ni, Co) nanoparticles, using the same steps of hydrocarbon dissociation, carbon intake into interstitial sites, and precipitation. It is generally assumed that the uptake of carbon in metal nanoparticles involves interstitial sites, similar to the bulk, but the stable concentrations (i.e., the carbon solubility) may be different at the nanoscale. The high surface-to-volume ratio of nanoparticles has been predicted to cause a significant increase of the solubility [26][27][28][29][30][31][32][33]. However, lattice relaxation in very small particles Electronic supplementary material The online version of this article

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“…When an epitaxial layer is grown around a bare nanowire, the interface strain will take place due to lattice misfit and can be obtained as ε m = (a s − a * c ) /a * c , where a * c and a s are the lattice constants of core interior and that of shell outside. 33,35 Notably, according to atomic-bond-relaxation consideration, [30][31][32][33][34] some quantities, such as lattice constant (a * c ), bond length (h c * 0 ) and single bond energy (E c * b ) of the core Si nanowire are different from those of the bulk counterpart. In the light of continuum mechanics, 33,35,36 the mean strain and stress in the core nanowire of a CSNW under cylindrical coordinates can be deduced as…”

Section: Principlementioning

confidence: 99%

“…[15][16][17][18][19][24][25][26][27][28] In fact, as the dimension of a device is reduced to nanometer scale, the effects of surface and interface play an important role in their physical and chemical properties. 29 According to the key idea of atomic-bond-relaxation consideration, [30][31][32][33][34] the bond identities of atoms located at the end parts such as surface and interface will be changed compared to those of the bulk case. Although many efforts about the thermal transport properties of CSNWs have been made to understand the relationship between interface and thermal conductivity, there are many important and fundamental issues remain unsolved.…”

Section: Introductionmentioning

confidence: 99%

Interface bond relaxation on the thermal conductivity of Si/Ge core-shell nanowires

Chen

Sun

et al. 2016

AIP Advances

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The thermal conductivity of Si/Ge core-shell nanowires (CSNWs) is investigated on the basis of atomic-bond-relaxation consideration and continuum mechanics. An analytical model is developed to clarify the interface bond relaxation of Si/Ge CSNWs. It is found that the thermal conductivity of Si core can be modulated through covering with Ge epitaxial layers. The change of thermal conductivity in Si/Ge CSNWs should be attributed to the surface relaxation and interface mismatch between inner Si nanowire and outer Ge epitaxial layer. Our results are in well agreement with the experimental measurements and simulations, suggesting that the presented method provides a fundamental insight of the thermal conductivity of CSNWs from the atomistic origin.

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Size dependence of nanostructures: Impact of bond order deficiency

Cited by 825 publications

References 673 publications

Local structure relaxation in nanosized tungstates

Local structure relaxation in nanosized tungstates

Giant carbon solubility in Au nanoparticles

Interface bond relaxation on the thermal conductivity of Si/Ge core-shell nanowires

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