The real background and peak asymmetry in diffraction on nanocrystalline metals

Kaszkur, Zbigniew; Zieliński, Maciej; Juszczyk, W.

doi:10.1107/s1600576717003235

Cited by 6 publications

(7 citation statements)

References 32 publications

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“…We would like to point out that there are also studies that do not find significant evidence of stress, for example, in gold and platinum particles. 70 However, in these cases, the peak profiles were found to be of asymmetric shape. Cline et al reported on the development of a zinc oxide standard reference material for the determination of domain sizes.…”

Section: ■ Results and Discussionmentioning

confidence: 93%

“…Further studies are needed to provide more precise ϵ, σ, u , and D hkl data, which in particular also provide uncertainties. We would like to point out that there are also studies that do not find significant evidence of stress, for example, in gold and platinum particles . However, in these cases, the peak profiles were found to be of asymmetric shape.…”

Section: Nanocrystalsmentioning

confidence: 84%

See 1 more Smart Citation

Microwave-Assisted Synthesis of Ultrasmall Zinc Oxide Nanoparticles

Saloga

Thünemann

2019

Langmuir

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We report on ultrasmall zinc oxide single-crystalline nanoparticles of narrow size distribution and long-term colloidal stability. These oleate-stabilized nanoparticles were synthesized using microwave-assisted synthesis for 5 min, corresponding to a 99% decrease in synthesis time, when compared to the conventional synthesis method. It was observed that the average particle radius increases from 2.6 ± 0.1 to 3.8 ± 0.1 nm upon increasing synthesis temperature from 125 to 200 °C. This change also corresponded to observed changes in the optical band gap and the fluorescence energy of the particles, from 3.44 ± 0.01 to 3.36 ± 0.01 eV and from 2.20 ± 0.01 to 2.04 ± 0.01 eV, respectively. Small-angle X-ray scattering, dynamic light scattering, and UV–vis and fluorescence spectroscopy were employed for particle characterization. Debye–Scherrer analysis of the X-ray diffraction (XRD) pattern reveals a linear increase of the crystallite size with synthesis temperature. The consideration of the convolution of a Lorentz function with a Gaussian function for data correction of the instrumental peak broadening has a considerable influence on the values for the crystallite size. Williamson–Hall XRD analyses in the form of the uniform deformation model, uniform stress deformation model, and uniform deformation energy density model revealed a substantial increase of strain, stress, and deformation energy density of the crystallites with decreasing size. Exponential and power law models were utilized for quantification of strain, stress, and deformation energy density.

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Section: ■ Results and Discussionmentioning

confidence: 93%

Section: Nanocrystalsmentioning

confidence: 84%

Microwave-Assisted Synthesis of Ultrasmall Zinc Oxide Nanoparticles

Saloga

Thünemann

2019

Langmuir

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“…The background subtraction required careful consideration of (a) the contributions of the specimen holder (sintered glass plate),(b) sample amorphous component and, (c) the scattering from the adsorption layer on the sample surface as well as from the content of the pores in the sample. The background subtraction could be performed precisely starting from estimation of the background profile for the sample in He (the He1 experiment stage is considered) by fitting its polycrystalline peaks to pairs (reflecting Cu K α 1 and K α 2 lines) of Voigt profiles following rules described before 37 . The residual scattering profile resulting from the best fit was accepted as a background for He.…”

Section: Diffraction Pattern Analysismentioning

confidence: 99%

In situ diffraction monitoring of nanocrystals structure evolving during catalytic reaction at their surface

Zieliński

Kaszkur²,

Juszczyk³

et al. 2022

Preprint

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With decreasing size of crystals the number of their surface atoms becomes comparable to the number of bulk atoms and their powder diffraction pattern becomes sensitive to a changing surface structure. On the example of nanocrystalline gold supported on also nanocrystalline CeO2 we show evolution of (a) the background pattern due to chemisorption phenomena, (b) peak positions due to changing concentration profile of O within nonstoichiometric CeO(2−x) particles, (c) Au peak intensity due to transport phenomena of gold atoms to the surface of ceria, varying amount of Au in the crystalline form. The results of the measurements, complemented with mass spectrometry gas analysis, point to a multiply twinned structure of gold, its high mobility and repeatable peak position on exposure to He-X-He when X is O2 , H2 ,CO or CO oxidation reaction mixture, suggesting no ceria lattice oxygen being consumed/supplied at any stage of the process. The work shows possibility of structurally interpreting different contributions to the multi-phase powder diffraction pattern during a complex physico-chemical process, including effects of physi- and chemisorption. It shows a way to structurally interpret surface evolution during a catalytic reaction involving no bulk phase transition.

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“…[5][6][7][8][9][10], to precisely control the hydrogenation pathway and, thus, to obtain desired products. The main scope of this work is to describe surface adsorption phenomena by in situ infrared (IR) spectroscopy that can later be utilised for studies of catalyst surface structure changes by means of various structuresensitive techniques arranged as in operando setups, including in operando electron microscopy, 11 in operando powder X-ray diffraction 12,13 and others e.g. ref.…”

Section: Introductionmentioning

confidence: 99%