Reactive diffusion in nanostructures of spherical symmetry

Schmitz, Guido; Ene, Cristian; Nowak, Carsten

doi:10.1016/j.actamat.2009.02.021

Cited by 31 publications

(22 citation statements)

References 19 publications

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“…[50,51] However,i nc ase of more complex materials, such as oxides,i ti sv ery rare that lattice resolution can be achieved, and only in af ew studies of non-metallic materials were lattice plane reconstructions obtained. [52,53] To exploit the resolution limit of atom probe reconstructions and to identify lattice planes in LMO,aFFT analysis of local distances from reconstructed atoms to an arbitrary reference plane was performed in this study as recently proposed.…”

Section: Experimental Section Materialsmentioning

confidence: 99%

Three‐Dimensional Microstructural Characterization of Lithium Manganese Oxide with Atom Probe Tomography

et al. 2016

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The microstructure of the active material of Li‐ion batteries has a crucial influence on local ion‐transport processes but is not yet well characterized. Atom probe tomography (APT), a method combining sub‐nanometer spatial resolution with sub‐parts‐per‐thousand chemical resolution is well suited for 3 D microstructural characterization. Herein, the results of the characterization of lithium (nickel)manganese oxides [L(N)MO] with APT are presented. Structural and chemical defects of different dimensions such as the segregation of Na impurities to grain boundaries and the appearance of a Ni‐rich foreign phase are detected. Furthermore, a lamellar microstructure correlated to fluctuations in the local Li content was observed, and its influence on Li transport in the material is discussed. In defect‐free regions, the lattice planes of LMO are reconstructed for the first time, and the high spatial resolution of APT is revealed. Thus, the results demonstrate the potential of APT for the 3 D microstructural characterization of LMO.

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Section: Experimental Section Materialsmentioning

confidence: 99%

Three‐Dimensional Microstructural Characterization of Lithium Manganese Oxide with Atom Probe Tomography

et al. 2016

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“…In addition, if the sample geometry is closed ͑cylindrical, spherical samples͒, since the stress free strain fields are long range fields, the stress development and relaxation will certainly depend on the shape and size of the sample and for example a radius dependence of the processes are also expected. 4,5 In extreme circumstances even a switching between the Darken and Nernst-Planck limits can be observed. 5 In the latter regime the intermixing is controlled by the diffusion of the slower component.…”

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confidence: 99%

“…4,5 In extreme circumstances even a switching between the Darken and Nernst-Planck limits can be observed. 5 In the latter regime the intermixing is controlled by the diffusion of the slower component. 4,5 Precursor experiments of hollow nanoshell formations were carried out by Aldinger 6 and by the Geguzin group.…”

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Production of hollow hemisphere shells by pure Kirkendall porosity formation in Au/Ag system

Glodán

Cserháti

Beszeda

et al. 2010

Applied Physics Letters

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Interdiffusion has been studied in Ag/Au hemispherical core-shell structures on sapphire substrate. In isothermal heat treatments first a relatively fast growth of nanovoids was observed, which was followed by a slower shrinkage process. The void formation is interpreted by pure Kirkendall-porosity formation since Ag-50%Au solid solution has been formed in the shell. In contrary, in all previous publications on hollow nanoshell formation a chemical reaction took place and the shell consisted of the reaction product ͑i.e., of sulphide or oxide͒. Furthermore, in these cases the shrinkage was observed at temperatures higher than the formation temperature. © 2010 American Institute of Physics. ͓doi:10.1063/1.3490675͔It is well-known that voids can be formed during interdiffusion in binary systems ͑Kirkendall porosity formation 1 or Frenkel effect 2,3 ͒. The origin of this effect is the resultant vacancy flow ͑caused by the inequality of the intrinsic atomic fluxes in the lattice frame of reference͒ oriented toward the faster component. In fact this resultant volume flow is responsible for the development of stress free strain in the diffusion zone: one side tends to shrink and the other one to expand. Additional stress free strains can also develop due to the difference of the atomic volumes and/or to the formation of intermetallic compounds in which the specific volumes of the constituents can be considerably different than in the parent phases. 4 The partial or full relaxation of these diffusional stresses can lead to the well-known Kirkendall shift: in case of vacancy mechanism, if the efficiency of the vacancy sources and sinks ͑at dislocations͒ is high enough, atomic planes will be removed/inserted at the corresponding fast/slow component of the diffusion couple. If this process is fast and complete then the stresses will be relaxed and the pure Darkenregime is realized. Thus the overall intermixing in the laboratory frame of reference is controlled by the larger diffusion coefficient. In real systems, however, more complex time evolution is expected. It can happen that the restricted efficiency of vacancy sinks leads to vacancy super saturation and porosity formation on the side of the faster component. These pores then can also sink vacancies and thus this will be a competing process with the vacancy annihilation at dislocations, i.e., with the Kirkendall shift. 2 Furthermore, the additional diffusional stresses can enhance or suppress the porosity formation. This complex interplay of the above effects is a delicate theoretical problem and it is expected that simple analytical solutions can work only at very special simple cases. In addition, if the sample geometry is closed ͑cylindrical, spherical samples͒, since the stress free strain fields are long range fields, the stress development and relaxation will certainly depend on the shape and size of the sample and for example a radius dependence of the processes are also expected. 4,5 In extreme circumstances even a switching between the Darken and Nernst-Pla...

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“…Due to the annealing process, the Al-Cu/Kapton alloys suffered thermal stresses as observed by curling of the samples. The residual stress is assumed to arise from shrinkage of the substrate up to 1% at 673 K (as reported by the supplier) and by the thermal diffusion of the material [13][14][15][16]. Additionally, 50 nm thick Figure 2, where a sample pressed by the clamps is shown (Figure 2 were examined by atomic force microscopy (AFM).…”

Section: Alloys Preparation and Substrate Selectionmentioning

confidence: 99%

Elastic Modulus Determination of Al‐Cu Film Alloys Prepared by Thermal Diffusion

Huerta

Oliva²,

Avilés

et al. 2012

Journal of Nanomaterials

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Elastic moduli of 50–250 nm thick Al-50 at % Cu film alloys deposited by thermal evaporation on Kapton substrates and postformed by thermal diffusion are investigated. Formation of the Al2Cu alloy phase was confirmed by X-ray photoelectron spectroscopy (XPS). Surface morphology was examined by atomic force microscopy (AFM) and scanning electron microscopy (SEM) before and after tensile mechanical testing. Force-strain curves of the Al-Cu alloy were obtained by subtracting the effect of the force-strain Kapton curves from the corresponding curves of the Al-Cu/Kapton system. A reduction in the elastic modulus of the Al-Cu alloys from 106.1 to 77.8 GPa with the increase of alloy thickness was obtained. Measured elastic moduli were between the reported bulk modulus for Al and Cu. Reductions in the surface roughness and increments in the grain size were measured after tensile testing of the Al-Cu alloys.

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Reactive diffusion in nanostructures of spherical symmetry

Cited by 31 publications

References 19 publications

Three‐Dimensional Microstructural Characterization of Lithium Manganese Oxide with Atom Probe Tomography

Three‐Dimensional Microstructural Characterization of Lithium Manganese Oxide with Atom Probe Tomography

Production of hollow hemisphere shells by pure Kirkendall porosity formation in Au/Ag system

Elastic Modulus Determination of Al‐Cu Film Alloys Prepared by Thermal Diffusion

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