Quantum size effect of valence band plasmon energies in Si and SnOx nanoparticles

Nienhaus, Hermann; Kravets, V. G.; Koutouzov, S.; Meier, Cedrik; Lorke, Axel; Wiggers, Hartmut; Kennedy, M.K.; Kruis, Frank Einar

doi:10.1116/1.2190658

Cited by 16 publications

(18 citation statements)

References 27 publications

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“…With decreasing particle size an increasing energy of the plasmon loss is observed. This is in good agreement to the results of Nienhaus et al [1] for SnO 1.5 to SnO 1.8 . The plasmon loss for 10 nm SnO 2 particles realized by annealing does not fit in this image.…”

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confidence: 94%

“…Interestingly, only little literature is dealing with quantum-confinement effects in SnO 2 . The minimum of the investigated particle size is 5 nm for SnO 1.5 to SnO 1.8 produced by gas condensation [1]. The Karlsruhe Microwave Plasma Process (KMPP) [2], a versatile gas-phase process, is able to produce nanoparticles with sizes below 5 nm, and narrow particle size distribution.…”

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confidence: 99%

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Analytical TEM Investigation of Size Effects in SnO2 Nanoparticles Produced by Microwave Plasma Synthesis

Szabó

Schlabach

Ochs

2007

Microsc. Microanal.

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Tin dioxide, a wide-band gap n-type semiconductor oxide, is a technologically interesting material with application potential in catalysis and as gas sensor. The semiconducting properties, such as band-gap, are particle-size dependent. The plasmon losses are influenced by size and shape of nanoparticles. Such influence is well known for many physical properties, especially for particles with sizes < 10 nm. Interestingly, only little literature is dealing with quantum-confinement effects in SnO 2 . The minimum of the investigated particle size is 5 nm for SnO 1.5 to SnO 1.8 produced by gas condensation [1]. The Karlsruhe Microwave Plasma Process (KMPP) [2], a versatile gas-phase process, is able to produce nanoparticles with sizes below 5 nm, and narrow particle size distribution. Therefore, in this study SnO 2 nanoparticles are produced with particle sizes ranging from 2 to 5 nm, depending on the synthesis conditions. For comparison larger particle sizes of 10 nm are realized by annealing the powders at 1000 C, to study the influence of particle size on plasmon and core losses in a broader range. A Tecnai F20 ST, equipped with a GATAN Multiscan CCD and GIF is used, operated at 200 kV. Sample preparation is done by dipping lacey carbon films into the powder. The powders are studied by bright-field and dark-field imaging, by electron diffraction and by EELS. Electron diffraction images are scanned (Imacon Flextight Photo) with 600 dpi. Crystallite sizes are evaluated from line profiles of the digitized images, using Scherrer formula. EEL-Spectra are acquired in image mode. The spectrometer dispersion is set to 0.3 eV/channel. Special care is taken to analyze sample areas without carbon film. The relative sample thicknesses are determined by logratio method to be t/ λ < 1 in all cases. Core loss spectra are deconvolved.Syntheses of SnO 2 nanoparticles result for all experimental conditions in a white powder. Electron diffraction reveals crystalline cassiterite particles. The particle sizes show a clear dependence on the feeding rate (corresponding to precursor concentration) of the SnCl 4 precursor. The smallest particles have sizes around 2 nm and are produced with a precursor concentration of 3x10 -6 mol/l. Although electron diffraction reveals more or less an amorphous like structure, crystalline nanoparticles are obvious in dark field imaging. At higher magnifications lattice fringes appear in bright field imaging. Figure 1 depicts the measured particle sizes as a function of the SnCl 4 -precursor concentration (Fig. 1a) and electron diffraction of the powders produced with the lowest (Fig. 1b) and the highest concentration (Fig. 1c).The general features of the low loss spectra are in good agreement with SnO 2 low loss spectra recorded by Powell [3]. Interband transitions are observed around 12.5 eV, the main bulk plasmon appears around 19 eV, and the Sn-N 4,5 peak around 32 eV. A broadening of the spectra and loss of features is observed with decreasing particle sizes. A well-defined peak at 27 eV, characterist...

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confidence: 94%

mentioning

confidence: 99%

Analytical TEM Investigation of Size Effects in SnO2 Nanoparticles Produced by Microwave Plasma Synthesis

Szabó

Schlabach

Ochs

2007

Microsc. Microanal.

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“…Quantum confinement in the silicon filaments is evidenced by an upward shift of the Si plasmon peak energy in electron energy-loss spectroscopy (EELS) with decreasing Si particle size. [24] The peak energy is 16.7 eV for crystalline Si, and shifts to 17.2 and 17.8 eV for 5-8 nm and 3-4 nm wide Si filaments respectively, and then vanishes for films with no or very small Si particles (Figures 3a-c). Figures 3e-f show the corresponding plan-view Si maps obtained with EFTEM.…”

Section: Doi: 101002/adma201104578mentioning

confidence: 95%

Silicon Filaments in Silicon Oxide for Next‐Generation Photovoltaics

et al. 2012

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“…With such composite materials a broad variety of applications can be covered, comprising optical, dielectric, electronic, magnetic, and mechanical properties of the polymer composite. Additionally, using nanoparticles as fillers opens new prospects, since many physical properties are size dependent (Han et al 1994;Kyprianidou-Leodidou et al 1994;Li et al 2004;Qi and Wang 2005;Nienhaus et al 2006;Luca 2009;Zhang et al 2009;Doak et al 2010). For a specific tailoring of composite properties, knowledge of functional properties of the filler material is mandatory.…”

Section: Introductionmentioning

confidence: 99%

Nanoparticles in polymer-matrix composites

et al. 2010

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Regarding the development of nanoparticles for polymer matrix composites the particle/agglomerate size and particle/agglomerate distribution in the composites, respectively, is often crucial. This is exemplarily shown for, e.g. optical applications with measurements of refractive index and transmittance. Classical blending techniques, where nanoparticles are dispersed in polymers or resins, are compared to a combination of a special gas-phase synthesis method with subsequent in-situ deposition of nanoparticles in high-boiling liquids. The particles/agglomerates were characterized regarding particle size and particle size distribution using transmission electron microscopy and dynamic light scattering. Additionally, important material properties like mechanical properties, relevant for application, or like viscosity, relevant for processing, are determined. It is shown, that with in-situ dispersed nanoparticles synthesized in a microwave plasma process composites with finely dispersed particles/agglomerates are attainable.

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Quantum size effect of valence band plasmon energies in Si and SnOx nanoparticles

Abstract: Articles you may be interested inSize and alloying induced shift in core and valence bands of Pd-Ag and Pd-Cu nanoparticles

Cited by 16 publications

References 27 publications

Analytical TEM Investigation of Size Effects in SnO2 Nanoparticles Produced by Microwave Plasma Synthesis

Analytical TEM Investigation of Size Effects in SnO2 Nanoparticles Produced by Microwave Plasma Synthesis

Silicon Filaments in Silicon Oxide for Next‐Generation Photovoltaics

Nanoparticles in polymer-matrix composites

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