Particle size distribution function of supported metal catalysts by X-ray diffraction

Ganesan, P.

doi:10.1016/0021-9517(78)90145-8

“…All samples reveal that the reflectivity is higher than the transmissivity in the whole investigated spectral range. However, Anesan et al [6], found that T > R for chemically prepared PbSe, films beside edges in both R and T. The difference between their results and ours is more likely due to the specular reflectance which is higher in our samples.…”

Section: Resultscontrasting

confidence: 60%

Optical Behaviour of Lead Selenide Films

El-Ocker

¹

,

Sharaf

²

,

Yossef

³

et al. 1990

Physica Status Solidi (b)

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Lead selenide thin films of thicknesses between 80 to 250 nm, are prepared by thermal evaporation under vacuum of -1.3 x Pa. X-ray diffraction studies reveal the formation of polycrystalline films. The optical gap is determined as a function of film thickness. It is observed that the width of the optical gap lies between 0.3 to 0.4 eV, additionally it shows the tendency t o decrease with increasing film thickness. Ellipsometry is used to estimate the optical constants and the absorption coefficient. Two well defined peaks are observed at energies of about 1.8 and 2.9 eV. The data are analysed in the frame of the band structure of PbSe,.

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“…Figures Ia and lb show the changes in the x-ray diffraction patterns with milling time for SmCo 5 and GdAI 2 . The initial material in both cases has fairly sharp x-ray diffraction peaks at the same Bragg angles as those expected for the bulk materials.…”

Section: Evolution Of the Nanostructurementioning

confidence: 99%

“…A single-profile analysis that separates linewidth broadening due to microstrain from broadening due to grain size was applied to extract the coherent diffracting crystallite size (DCS) and rootmean-squared microstrain [5]. The GdAI 2 data were analyzed using an integral-breadth technique after the K,1 2 contributions were removed from the (111) diffraction peak.…”

Section: Evolution Of the Nanostructurementioning

confidence: 99%

“…We therefore must settle for parameterizing these data in terms of milling time. Figure 4 shows the dependence of the coercivity H, and the remanence ratio M,/M, on milling time for SmCo 5 . The dependence of the coercivity on milling time appears similar to that expected for particles passing from multi-domain to single domain and finally to superparamagnetic sizes; however, the grain size changes from 20 nm to 4 nm during the period of greatest change in the magnetic properties.…”

Section: Sa)mentioning

confidence: 99%

“…This paper compares the magnetic behavior of two mechanically milled alloys. SmCo 5 and GdA1 2 are both ferromagnetic in their crystalline state. The goal of this paper is to understand how the nanostructure produced by mechanical milling affects the ferromagnetism and, in particular, how milling can induce a change in magnetic ordering from ferromagnetic to spinglass-like.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Role of Disorder in the Magnetic Properties of Mechanically Milled Nanostructured Alloys

Leslie‐Pelecky

¹

,

Kirkpatrick

²

,

Pekarek

³

et al. 2001

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Mechanical milling provides a unique means of studying the influence of grain size and disorder on the magnetic properties of nanostructured alloys. This paper compares the role of milling in the nanostructure evolution of two ferromagnets -SmCo 5 and GdAI 2 -and the subsequent impact of nanostructure on magnetic properties and phase transitions. The ferromagnetic properties of SmCo 5 are enhanced by short (< 2 hours) milling times, producing up to an eight-fold increase in coercivity and high remanence ratios. The coercivity increase is attributed to defect formation and strain. Additional milling increases the disorder and produces a mix of ferromagnetic and antiferromagnetic interactions that form a magnetically glassy phase. GdA1 2 , which changes from ferromagnetic in its crystalline form to spin-glass-like in its amorphous form, is a model system for studying the dependence of magnetically glassy behavior on grain size and disorder. Nanostructured GdAI 2 with a mean grain size of 8 nm shows a combination of ferromagnetic and magnetically glassy behavior, in contrast to previous studies of nanostructured GdA1 2 with a grain size of 20 nm that show only spin-glass-like behavior.

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Particle Size and Dispersion Measurements

Bergeret¹,

Gallezot²

2008

Handbook of Heterogeneous Catalysis

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The sections in this article are Definitions and Generalities Particles Particle Size Nuclearity of Particles Dispersion Relationships Between Particle Size, Surface Area and Dispersion Methods of Particle Size Measurement Particle Size Measurements by Gas Chemisorption Introduction and Principles Gas Adsorption–Desorption Methods A Static Methods B Dynamic Methods C Desorption Methods Choice of Adsorbate Gases Hydrogen Chemisorption; HydrogenOxygen Titration Conclusion and Recommendations X ‐Ray Diffraction Line Broadening Analysis Introduction Elementary Line Broadening Analysis: the Scherrer Equation Complete Line Profile Analysis: the W arren– A verbach Method Examples of Application of Classical LBA to Catalysts Whole‐Powder Pattern Fitting Methods: the Rietveld Refinement Limits of Application of Methods Conclusion Small‐Angle X ‐Ray Scattering Analysis Introduction Specific Surface Area Measurements: P orod's Law Mean Size Parameters: Guinier Radius Calculation of Size Distribution Application of SAXS to Metal Particle Size Determination in Supported Catalysts Anomalous Small‐Angle X ‐Ray Scattering ( ASAXS ) Conclusion Determination of Particle Size by Electron Microscopy Scope Fundamentals of Imaging and Contrast A Transmission Electron Microscope B Scanning Transmission Electron Microscope C Scanning Electron Microscope Preparation of Samples for TEM and STEM Examination Particle Size Measurement Selected Examples of Particle Size Distribution Selected Examples of 3D Localization of Particles in Supports by Electron Tomography Particle Size Measurements by Magnetic Methods

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Particle size distribution function of supported metal catalysts by X-ray diffraction

Cited by 88 publications

References 21 publications

Optical Behaviour of Lead Selenide Films

Optical Behaviour of Lead Selenide Films

The Role of Disorder in the Magnetic Properties of Mechanically Milled Nanostructured Alloys

Particle Size and Dispersion Measurements

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