Temperature dependence of thermal expansion coefficient of silver nanoparticles and of bulk material determined by EXAFS

Dubiel, M.; Brunsch, S.; Tröger, L.

doi:10.1107/s0909049500016666

Cited by 26 publications

(17 citation statements)

References 7 publications

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“…Final grain sizes in similar films annealed at similar temperatures (without added bulge stresses) were about 1800 nm [31]. these values and assuming δ = 145 pm (b/2 [26], where b is the magnitude of the Burgers vector [32]), we find the strain due to shrinking of the grains to be -1.53 × 10 -3 ( Table 1). Note that this shows that grain growth provides the largest strain in the problem (Δε th = -8.28 × 10 -4 (Eq.…”

Section: Stress Calculationsmentioning

confidence: 81%

Driving forces for texture transformation in thin Ag films

et al. 2016

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The well-known thickness-dependent (111)-to-(100) texture transformation in thin FCC films is usually attributed to a competition between interface and strain energies. In this model, thin films retain their (111) texture due to the lower energy of the (111) interface, while thick films transform to (100) due to the lower stiffness and thus strain energy of a (100) film. However, recent work has called this model into question, suggesting that neither the stress nor the interface energy play a dominant role in texture transformation. We investigated the driving forces involved in this transformation by using a bulge test apparatus to induce different stresses in thin Ag films under identical annealing conditions. In situ synchrotron XRD measurements show the change in texture during annealing, and reveal that applied stresses have no effect on the transformation. Stress analysis shows that differences in driving forces for texture transformation due to applied bulge pressure were significant (≈200 kJ/m 3 ), suggesting that a different, much larger driving force must be responsible. Reduction in defect energy has been proposed as an alternative. However, vacancy and dislocation densities must be exceptionally high to significantly exceed the strain energy and do not provide obvious orientation selection © 2016. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ mechanisms. Nanotwins in reported densities are shown to provide greater driving force (≈ 1000 kJ/m 3 ) and may account for orientation selection. The large difference between the calculated strain and defect energies and the driving force for grain growth (21,100 kJ/m 3 ) casts doubt on the applicability of a simple thermodynamic model of texture transformation.

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Section: Stress Calculationsmentioning

confidence: 81%

Driving forces for texture transformation in thin Ag films

et al. 2016

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“…60 In addition, the $0.3% decrease in Ag layer thickness due to thermal contraction during cooling to 77 K, calculated using a thermal expansion coefficient of a Ag ¼ 15 Â 10 À6 K À1 (Ref. 53), results in a negligible correction of $ 0.3% for q 77 K in Fig. 5.…”

Section: Methodsmentioning

confidence: 99%

“…In contrast, the layer with T s ¼ 300 C indicates a twice-as-large tensile stress, which may be attributed to the differential thermal contraction during cooling to room temperature after deposition with a thermal expansion coefficient of a Ag ¼ 15 Â 10 À6 K À1 (Ref. 53) and a MgO ¼ 9-13 Â 10 À6 K À1 (Ref. 54).…”

Section: Methodsmentioning

confidence: 99%

Epitaxial Ag(001) grown on MgO(001) and TiN(001): Twinning, surface morphology, and electron surface scattering

Chawla

Gall

2012

Journal of Applied Physics

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Morphology of TiN thin films grown on MgO (001) by reactive dc magnetron sputtering J. Vac. Sci. Technol. A 28, 912 (2010); 10.1116/1.3357303Oxygen-assisted control of surface morphology in nonepitaxial sputter growth of Ag Interdependence between stress, preferred orientation, and surface morphology of nanocrystalline TiN thin films deposited by dual ion beam sputtering Epitaxial Ag(001) layers were deposited on MgO(001) in order to study electron surface scattering. X-ray reflection indicates 3D layer nucleation with a high rms surface roughness of 1.0 nm for a layer thickness d ¼ 3.5 nm. X-ray diffraction shows that f111g twins form at d < 11 nm, followed by 2nd generation twinning for 11 nm < d < 120 nm. Increasing the growth temperature from 25 to 150 C suppresses 2nd generation twinning and reduces the twin density by 2 orders of magnitude. In situ deposition of epitaxial 2.5-nm-thick TiN(001) underlayers prior to Ag deposition results in twin-free single-crystal Ag(001) with 10 Â smoother surfaces for d ¼ 3.5 nm. This is attributed to a better wetting on the higher energy TiN(001) than MgO(001) surface, resulting in the absence of 3D nuclei with exposed f111g facets, which facilitate twin nucleation. The twinned Ag/MgO layers have a higher resistivity q than the single crystal Ag/TiN layers at both 298 and 77 K, due to electron scattering at grain and twin boundaries. The q for single-crystal Ag layers increases with decreasing d, which is well explained with known surface scattering models and provides specularity parameters for the Ag-vacuum and the Ag-air interfaces of p ¼ 0.8 6 0.1 and 0.4 6 0.1, respectively. A comparison with corresponding epitaxial Cu(001) layers shows that q Ag < q Cu for d > 50 nm, consistent with known bulk values. However, q Ag > q Cu for d < 40 nm. This is attributed to the larger electron mean free path for electron-phonon scattering and a correspondingly higher resistivity contribution from surface scattering in Ag than Cu. In contrast, air exposure causes q Ag < q Cu for all d, due to diffuse scattering at the oxidized Cu surface and the correspondingly higher Cu resistivity.

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“…The evaluation of the EXAFS data of small NPs typically provides a decreased coordination number, a dilatation or a contraction of the lattice structure and an increased Debye-Waller factor, together with an increased static disorder. 32 In addition, EXAFS does not require operation under vacuum, in contrast to XPS. It was used by the Parkin group to investigate the phase change in silver speciation, during the photo-assisted growth of Ag from AgNO 3 .…”

Section: X-ray-based Techniquesmentioning

confidence: 99%

Characterization techniques for nanoparticles: comparison and complementarity upon studying nanoparticle properties

2018

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Nanostructures have attracted huge interest as a rapidly growing class of materials for many applications. Several techniques have been used to characterize the size, crystal structure, elemental composition and a variety of other physical properties of nanoparticles. In several cases, there are physical properties that can be evaluated by more than one technique. Different strengths and limitations of each technique complicate the choice of the most suitable method, while often a combinatorial characterization approach is needed. In addition, given that the significance of nanoparticles in basic research and applications is constantly increasing, it is necessary that researchers from separate fields overcome the challenges in the reproducible and reliable characterization of nanomaterials, after their synthesis and further process (e.g. annealing) stages. The principal objective of this review is to summarize the present knowledge on the use, advances, advantages and weaknesses of a large number of experimental techniques that are available for the characterization of nanoparticles. Different characterization techniques are classified according to the concept/group of the technique used, the information they can provide, or the materials that they are destined for. We describe the main characteristics of the techniques and their operation principles and we give various examples of their use, presenting them in a comparative mode, when possible, in relation to the property studied in each case.

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Temperature dependence of thermal expansion coefficient of silver nanoparticles and of bulk material determined by EXAFS

Cited by 26 publications

References 7 publications

Driving forces for texture transformation in thin Ag films

Driving forces for texture transformation in thin Ag films

Epitaxial Ag(001) grown on MgO(001) and TiN(001): Twinning, surface morphology, and electron surface scattering

Characterization techniques for nanoparticles: comparison and complementarity upon studying nanoparticle properties

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