The effect of particles on the absorption factor for diffracted X-rays in single-phase powders measured at cylindrical geometry— a computational study

1998 ◽  
Vol 13 (4) ◽  
pp. 249-253
Author(s):  
J. Collazo ◽  
H. Hermann ◽  
A. Teresiak ◽  
K. Wetzig
Keyword(s):  
Single Phase ◽  
Fine Particles ◽  
Computational Study ◽  
X Rays ◽  
Absorption Factor ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
Powder Particles ◽  
Dense Packings ◽  
The Ideal

The results of computer simulations of the absorption of diffracted X-rays in single-phase powders measured at cylindrical (or Debye–Scherrer capillary) geometry taking into consideration the size of the powder particles are presented. The samples are simulated by random dense packings of equal spheres. The calculations are carried out for different values of the ratio, Da, of particle size to cylinder diameter, the product, κ, of linear absorption coefficient and cylinder radius and the scattering angle 2θ. Strong deviations of the absorption factor from the values for the ideal case of very fine particles are found in the region 0≤2θ≤30°, and for medium and high values of κ,(κ≥5) and Da (Da≥0.002). The consequences for the experiment are discussed.

Superstructure Determination of PbZrO3

1998 ◽  
Vol 54 (5) ◽  
pp. 524-530 ◽  
Author(s):  
K. Yamasaki ◽  
Y. Soejima ◽  
K. F. Fischer
Keyword(s):  
Structure Refinement ◽  
Lead Zirconate ◽  
X Rays ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
Acta Cryst ◽  
X Ray ◽  
Domain Structures ◽  
X Ray Absorption

By taking into account the effects of domain structures and X-ray absorption, the superstructure of PbZrO3, lead zirconate, has been determined at room temperature. The space group is Pbam with a unit cell of a = 5.8884 (19), b = 11.771 (4) and c = 8.226 (3) Å, with Z = 8. The intensity data were collected using short-wavelength synchrotron X-rays of 0.350 Å; this reduces the linear absorption coefficient to 11.93 mm−1. The structure refinement was performed using only the data of superlattice reflections which are free from ambiguity and resulting from the domain structure; the final R value is 0.047 for 335 unique superlattice reflections. Zr atoms show the antiphase-type displacement along the z axis; oxygen octahedra show tilt of the type a − a − c 0 using Glazer's [Acta Cryst. (1972), B28, 3384–3392; Acta Cryst. (1975), A31, 756–762] notation.

Détermination du coefficient d'absorption des rayons X à partir des mesures de réflectométrie X

2004 ◽  
Vol 82 (1) ◽  
pp. 75-79 ◽  
Author(s):  
E Ech-chamikh ◽  
I Aboudihab ◽  
M Azizan ◽  
A Essafti ◽  
Y Ijdiyaou
Keyword(s):  
Absorption Coefficient ◽  
Amorphous Carbon ◽  
X Rays ◽  
Absorption Coefficients ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
Simple Method ◽  
Material Layer ◽  
Reflectivity Spectra ◽  
Good Agreement

In this paper, we present a simple method that allows, among other things, to determine the absorption coefficient of X-rays from reflectivity measurements. This method is applicable if the analysed material is deposited on a substrate denser than the material layer, so that the X-rays reflectivity spectra exhibit two well-resolved descents. In such cases, the amplitude of the first descent (characteristic of the material layer) is directly related to the linear absorption coefficient of the material constituting the layer. We have been able to clarify this relationship and apply it successfully for several cases of materials, especially amorphous carbon and silicon. Values of thus obtained mass absorption coefficients are in very good agreement with those tabulated in the literature.[Journal translation]

scholarly journals Al-driven peculiarities of local coordination and magnetic properties in single-phase Alx-CrFeCoNi high-entropy alloys

Nano Research ◽  
2021 ◽  
Author(s):  
Alevtina Smekhova ◽  
Alexei Kuzmin ◽  
Konrad Siemensmeyer ◽  
Chen Luo ◽  
Kai Chen ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Single Phase ◽  
Magnetic Circular Dichroism ◽  
Surface Region ◽  
Face Centered Cubic ◽  
X Rays ◽  
X Ray ◽  
High Entropy ◽  
X Ray Absorption ◽  
Absorption Edges

AbstractModern design of superior multi-functional alloys composed of several principal components requires in-depth studies of their local structure for developing desired macroscopic properties. Herein, peculiarities of atomic arrangements on the local scale and electronic states of constituent elements in the single-phase face-centered cubic (fcc)- and body-centered cubic (bcc)-structured high-entropy Alx-CrFeCoNi alloys (x = 0.3 and 3, respectively) are explored by element-specific X-ray absorption spectroscopy in hard and soft X-ray energy ranges. Simulations based on the reverse Monte Carlo approach allow to perform a simultaneous fit of extended X-ray absorption fine structure spectra recorded at K absorption edges of each 3d constituent and to reconstruct the local environment within the first coordination shells of absorbers with high precision. The revealed unimodal and bimodal distributions of all five elements are in agreement with structure-dependent magnetic properties of studied alloys probed by magnetometry. A degree of surface atoms oxidation uncovered by soft X-rays suggests different kinetics of oxide formation for each type of constituents and has to be taken into account. X-ray magnetic circular dichroism technique employed at L2.3 absorption edges of transition metals demonstrates reduced magnetic moments of 3d metal constituents in the sub-surface region of in situ cleaned fcc-structured Al0.3-CrFeCoNi compared to their bulk values. Extended to nanostructured versions of multicomponent alloys, such studies would bring new insights related to effects of high entropy mixing on low dimensions.

A high-energy triple-axis X-ray diffractometer for the study of the structure of bulk crystals

2004 ◽  
Vol 37 (6) ◽  
pp. 901-910 ◽  
Author(s):  
C. Seitz ◽  
M. Weisser ◽  
M. Gomm ◽  
R. Hock ◽  
A. Magerl
Keyword(s):  
High Energy ◽  
X Rays ◽  
Bulk Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Intensity ◽  
High Penetration ◽  
Massive Sample ◽  
Laue Geometry ◽  
The Ideal

A triple-axis diffractometer for high-energy X-ray diffraction is described. A 450 kV/4.5 kW stationary tungsten X-ray tube serves as the X-ray source. Normally, 220 reflections of thermally annealed Czochralski Si are employed for the monochromator and analyser. Their integrated reflectivity is about ten times higher than the ideal crystal value. With the same material as the sample, and working with the WKα line at 60 keV in symmetric Laue geometry for all axes, the full width at half-maximum (FWHM) values for the longitudinal and transversal resolution are 2.5 × 10−3and 1.1 × 10−4for ΔQ/Q, respectively, and the peak intensity for a non-dispersive setting is 3000 counts s−1. In particular, for a double-axis mode, an energy well above 100 keV from theBremsstrahlungspectrum can be used readily. High-energy X-rays are distinguished by a high penetration power and materials of several centimetre thickness can be analysed. The feasibility of performing experiments with massive sample environments is demonstrated.

scholarly journals Methotrexate Detection Based On The Optical Properties Of Carbon Nanotubes And Silver Nano Particles Nanocomposites

2021 ◽  
Vol 7 (3) ◽  
pp. 1323
Author(s):  
Fida Mohammad Mohammadi
Keyword(s):  
Carbon Nanotubes ◽  
Refractive Index ◽  
Nonlinear Refractive Index ◽  
Nano Particles ◽  
Optical Measurements ◽  
Carbon Electrode ◽  
Linear Absorption Coefficient ◽  
Linear Absorption ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

<p>In this experiment, glassy carbon electrode with multi walled carbon nanotubes<br />nanocomposites have been prepared in different concentration in order to see if<br />methotrexate is anticancer drug. For the purpose of characterizing the structures,<br />nanocomposites were analyzed by scanning electron microscope. Optical measurements of different concentrations were conducted by z-scan method and the results show that by rising the concentration, nonlinear refractive index and linear absorption coefficient increases. The values of nonlinear refractive index are in orders of 𝟏𝟎−𝟖 𝒄𝒎𝟐 𝒘.</p>

scholarly journals Study the Shielding Properties against Gamma-rays for Epoxy Resin Reinforced by Different materials

2016 ◽  
Vol 8 (3) ◽  
pp. 705-710
Author(s):  
Baghdad Science Journal
Keyword(s):  
Epoxy Resin ◽  
Aluminum Powder ◽  
Gamma Rays ◽  
Scintillation Detector ◽  
Buildup Factor ◽  
Absorption Factor ◽  
Linear Absorption ◽  
Increase With Increase ◽  
Lead Powder ◽  
Shielding Properties

In the present work the Buildup factor for gamma rays were studied in shields from epoxy reinforced by lead powder and by aluminum powder, for NaI(Tl) scintillation detector size ( ×? ), using two radioactive sources (Co-60 and Cs-137). The shields which are used (epoxy reinforced by lead powder with concentration (10-60)% and epoxy reinforced by aluminum powder with concentration (10-50)% by thick (6mm) and epoxy reinforced by lead powder with concentration (50%) with thick (2,4,6,8,10)mm. The experimental results show that: The linear absorption factor and Buildup factor increase with increase the concentration for the powders which used in reinforcement and high for aluminum powder than the lead powder and decrease with increase thick the shields. It’s for Cs-137 higher than Co-60 source.

Normale und anomale Absorption von Röntgen-Strahlen in Germanium und Silicium/Normal and anomalous absorption of X-rays in Germanium and Silicon

1973 ◽  
Vol 28 (5) ◽  
pp. 588-600 ◽  
Author(s):  
G. Hildebrandt ◽  
J. D. Stephenson ◽  
H. Wagenfeld
Keyword(s):  
Cross Sections ◽  
Theoretical Data ◽  
Electric Quadrupole ◽  
Photoelectric Effect ◽  
Waller Factor ◽  
Dynamical Theory ◽  
X Rays ◽  
Linear Absorption ◽  
Debye Waller Factor ◽  
Silicon And Germanium

A brief discussion of G. Molière's generalized dynamical theory is given with respect to the interpretation of the experimental data|χ⊥ig/χi0 |obtained by means of the Borrmann effect. In order to compare theory and experiment photoelectric absorption cross sections for Silicon and Germanium have been calculated over the X-ray energy range from 5 to 25 keV. Linear absorption coefficients measured by us and other authors agree with theory within a few per cent. Taking the Debye-Waller factor into account, the same theoretical data have been used to calculate |χ⊥ig/χi0 | for Ge and Si. The agreement with extensive measurements of the Borrmann effect in Ge is very good in most cases. The experiments presented in this paper confirm the existence of the electric quadrupole transitions within the photoelectric effect.

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