scholarly journals Accounting for the Local Field When Determining the Dielectric Loss Spectra of Metals in the Region of the Frequencies of Volume, Surface and Localized Plasmon Oscillations

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 631 ◽  
Author(s):  
Tatiana Perova ◽  
Igor Shaganov ◽  
Kevin Berwick
Keyword(s):  
Dielectric Loss ◽  
Local Field ◽  
Alkali Metals ◽  
Collective Motion ◽  
Three Dimensional ◽  
Spherical Particles ◽  
Dielectric Losses ◽  
Free Electrons ◽  
Plasma Oscillations ◽  
Alkali Halide Crystals

The optical constant of bulk metal is used to determine the dispersion of the local field under one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) confinement. 3D confinement, expressed as ε 2 m i c ( ω 3 D ) , corresponds to the dielectric loss spectra of spherical particles with a diameter, d, much less than the wavelength of the beam used to measure the spectrum (d << λ). Excellent agreement with the results of Mie theory and experimental data for solid colloids within alkali halide crystals was observed. The function expressed as ε 2 m i c ( ω 1 D ) allows the measurement of spectral micro-characteristics in the frequency range of the longitudinal collective motion of the free electrons. This corresponds to the spectrum of dielectric losses of bulk plasma oscillations. The function ε 2 m i c ( ω 2 D ) describes the spectra of the dielectric losses of surface plasma oscillations in thin metal films. It is shown that the peak positions of ε 2 m i c ( ω 3 D ) , ε 2 m i c ( ω 2 D ) and ε 2 m i c ( ω 1 D ) spectra for simple metals, viz. alkali metals as well as Al, Be, Mg, Ga, In, Sn and Si, are in agreement with experimental results from electron-energy-loss spectroscopy and various optical techniques.

Dielectric and Magnetic Properties of Nanocomposites Based on Opal Matrixes, Phosphates and Vanadates of Metals

2019 ◽  
Vol 970 ◽  
pp. 100-106
Author(s):  
Alexey F. Belyanin ◽  
Sergey A. Bagdasaryan ◽  
Alexander S. Bagdasaryan ◽  
Alexander I. Yurin ◽  
Anatoly P. Surzhikov
Keyword(s):  
Magnetic Properties ◽  
Dielectric Loss ◽  
Spherical Particles ◽  
Dielectric Losses ◽  
Opal Matrix ◽  
Frequency Range ◽  
Low Frequencies ◽  
3D Packing ◽  
Magnetic Conductivity ◽  
Frequency Dependences

Opal matrix is a regular 3D-packing of spherical particles of amorphous SiO2, forming an ordered system of voids. Opal matrixes with spherical particles of SiO2 diameter d ≈ 260 nm (Δd ≈ 2 %) were synthesized. The frequency dependences of the conductivity, real and imaginary components of the dielectric and magnetic conductivity of nanocomposites containing crystallites 16–65 nm in size of magnetic materials ‒ double phosphates (LiNiPO4, LiCoPO4) and vanadates (GdVO4 and DyVO4) were measured. The dielectric losses of nanocomposites remain low (at a level of ~ 0.06) in the frequency range 107–1010 Hz for nanocomposites with DyVO4 and LiCoPO4. The dielectric loss increases both in the direction of low frequencies (< 106 Hz) and in the direction of THz frequencies.

Analysis of migration paths in fast-ion conductors with Voronoi–Dirichlet partition

2006 ◽  
Vol 62 (6) ◽  
pp. 1010-1018 ◽  
Author(s):  
Vladislav A. Blatov ◽  
Gregory D. Ilyushin ◽  
Olga A. Blatova ◽  
Nataly A. Anurova ◽  
Alexej K. Ivanov-Schits ◽  
...  
Keyword(s):  
Alkali Metals ◽  
Three Dimensional ◽  
Charge Carriers ◽  
Alkali Cations ◽  
Fast Ion Conductors ◽  
And Migration ◽  
Crystal Space ◽  
Fast Ion ◽  
Dirichlet Partition ◽  
Ion Conductors

In terms of the Voronoi–Dirichlet partition of the crystal space, definitions are given for such concepts as `void', `channel' and `migration path' for inorganic structures with three-dimensional networks of chemical bonds. A number of criteria are proposed for selecting significant voids and migration channels for alkali cations Li+–Cs+ based on the average characteristics of the Voronoi–Dirichlet polyhedra for alkali metals in oxygen-containing compounds. A general algorithm to analyze the voids in crystal structures has been developed and implemented in the computer package TOPOS. This approach was used to predict the positions of Li+ and Na+ cations and to analyze their possible migration paths in the solid superionic materials Li3 M 2P3O12 (M = Sc, Fe; LIPHOS) and Na1 + x Zr2Si x P3 − x O12 (NASICON), whose framework structures consist of connected M octahedra and T tetrahedra. Using this approach we determine the most probable places for charge carriers (coordinates of alkali cations) and the dimensionality of their conducting sublattice with high accuracy. The theoretically calculated coordinates of the alkali cations in MT frameworks are found to correlate to within 0.33 Å with experimental data for various phases of NASICON and LIPHOS. The proposed method of computer analysis is universal and suitable for investigating fast-ion conductors with other conducting components.

Effective Stiffness of a Debonded Particle in Particulate Composites

2007 ◽  
Vol 334-335 ◽  
pp. 33-36 ◽  
Author(s):  
Akihiro Wada ◽  
Yusuke Nagata ◽  
Shi Nya Motogi
Keyword(s):  
Three Dimensional ◽  
Particulate Composite ◽  
Spherical Particles ◽  
Particulate Composites ◽  
Particle Volume ◽  
Equivalent Inclusion Method ◽  
Equivalent Inclusion ◽  
Load Carrying ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

In this study, partially debonded spherical particles in a particulate composite are analyzed by three-dimensional finite element method to investigate their load carrying capacities, and the way to replace a debonded particle with an equivalent inclusion is examined. The variation in Young’s modulus and Poisson’s ratio of a composite with the debonded angle was evaluated for different particle arrangements and particle volume fractions, which in turn compared with the results derived from the equivalent inclusion method. Consequently, it was found that by replacing a debonded particle with an equivalent orthotropic one, the macroscopic behavior of the damaged composite could be reproduced so long as the interaction between neighboring particles is negligible.

Darcy-Forchheimer porous medium effect on rotating hybrid nanofluid on a linear shrinking/stretching sheet

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Liaquat Ali Lund ◽  
Zurni Omar ◽  
Ilyas Khan
Keyword(s):  
Porous Medium ◽  
Stability Analysis ◽  
Differential Equations ◽  
Three Dimensional ◽  
Spherical Particles ◽  
Medium Effect ◽  
Hybrid Nanofluid ◽  
Three Dimensional Flow ◽  
Content Type ◽  
Dimensional Flow

Purpose The purpose of this study is to find the multiple branches of the three-dimensional flow of Cu-Al2 O3/water rotating hybrid nanofluid perfusing a porous medium over the stretching/shrinking surface. The extended model of Darcy due to Forchheimer and Brinkman has been considered to make the hybrid nanofluid model over the pores by considering the porosity and permeability effects. Design/methodology/approach The Tiwari and Das model with the thermophysical properties of spherical particles for efficient dynamic viscosity of the nanoparticle is used. The linear similarity transformations are applied to convert the partial differential equations into ordinary differential equations (ODEs). The system of governing ODEs is solved by using the three-stage Lobatto IIIa scheme in MATLAB for evolving parameters. Findings The system of governing ODEs produces dual branches. A unique stable branch is identified with help of stability analysis. The reduced heat transfer rate has been shown to increase with the reduced ϕ2 in both branches. Further, results revealed that the presence of multiple branches depends on the ranges of porosity, suction and stretching/shrinking parameters for the particular value of the rotating parameter. Originality/value Dual branches of the three-dimensional flow of Cu-Al2 O3/water rotating hybrid nanofluid have been found. Therefore, stability analysis of the branches is also conducted to know which branch is appropriate for the practical applications. To the best of the authors’ knowledge, this research is novel and there is no previously published work relevant to the present study.

scholarly journals Derivation of Equations for a Size Distribution of Spherical Particles in Non-Transparent Materials

2021 ◽  
Vol 5 (4) ◽  
pp. 53-60
Author(s):  
Daniel Gurgul ◽  
Andriy Burbelko ◽  
Tomasz Wiktor
Keyword(s):  
Probability Density Function ◽  
Probability Density ◽  
Size Distribution ◽  
Density Function ◽  
Cross Section ◽  
Three Dimensional ◽  
Spherical Particles ◽  
Two Dimensional ◽  
Mathematical Formulas ◽  
Transparent Materials

This paper presents a new proposition on how to derive mathematical formulas that describe an unknown Probability Density Function (PDF3) of the spherical radii (r3) of particles randomly placed in non-transparent materials. We have presented two attempts here, both of which are based on data collected from a random planar cross-section passed through space containing three-dimensional nodules. The first attempt uses a Probability Density Function (PDF2) the form of which is experimentally obtained on the basis of a set containing two-dimensional radii (r2). These radii are produced by an intersection of the space by a random plane. In turn, the second solution also uses an experimentally obtained Probability Density Function (PDF1). But the form of PDF1 has been created on the basis of a set containing chord lengths collected from a cross-section.The most important finding presented in this paper is the conclusion that if the PDF1 has proportional scopes, the PDF3 must have a constant value in these scopes. This fact allows stating that there are no nodules in the sample space that have particular radii belonging to the proportional ranges the PDF1.

scholarly journals Clusters Formed by Dumbbell-like One-Patch Particles Confined in Thin Systems

2021 ◽  
Author(s):  
Masahide Sato
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Particle Interaction ◽  
Three Dimensional ◽  
The Other ◽  
Spherical Particles ◽  
Dimensionless Distance ◽  
Large Island ◽  
Cluster Shape

Abstract Performing isothermal-isochoric Monte Carlo simulations, I examine the types of clusters that dumbbell-like one–patch particles form in thin space between two parallel walls, assuming that each particle is synthesized through the merging of two particles, one non-attracting and the other attracting for which, for example, the inter-particle interaction is approximated by the DLVO model. The shape of these dumbbell-like particles is controlled by the ratio of the diameters q of the two spherical particles and by the dimensionless distance l between them. Using a modified Kern–Frenkel potential, I examine the dependence of the cluster shape on l and q. Large island-like clusters are created when q < 1. With increasing q, the clusters become chain-like. When q increases further, elongated clusters and regular polygonal clusters are created. In hte simulations, the cluster shape becomes three-dimensional with increasing l because the thickness of the thin system increases proportionally to l.

scholarly journals Numerical Study of Branched Turboprop Inlet Ducts Using a Multiple Block Grid Procedure

1991 ◽  
Author(s):  
Anil K. Tolpadi ◽  
Mark E. Braaten
Keyword(s):  
Numerical Solutions ◽  
Numerical Study ◽  
Three Dimensional ◽  
Separated Flow ◽  
Experimental Tests ◽  
Spherical Particles ◽  
Branch Duct ◽  
Pressure Losses ◽  
Overlapping Grids ◽  
Inlet Duct

An important requirement in the design of an inlet duct of a turboprop engine is the ability to provide foreign object damage protection. A possible method for providing this protection is to include a bypass branch duct as an integral part of the main inlet duct. This arrangement would divert ingested debris away from the engine through the bypass. However, such an arrangement could raise the possibility of separated flow in the inlet, which in turn can increase pressure losses if not properly accounted for during the design. A fully elliptic three-dimensional body-fitted computational fluid dynamics (CFD) code based on pressure correction techniques has been developed that has the capability of performing multiple block grid calculations compatible with present day turboshaft and turboprop branched inlet ducts. Calculations are iteratively performed between sets of overlapping grids with one grid representing the main duct and a second grid representing the branch duct. Both the grid generator and the flow solver have been suitably developed to achieve this capability. The code can handle multiple branches in the flow. Using the converged flow field from this code, another program was written to perform a particle trajectory analysis. Numerical solutions were obtained on a supercomputer for a typical branched duct for which experimental flow and pressure measurements were also made. The flow separation zones predicted by the calculations were found to be in good agreement with those observed in the experimental tests. The total pressure recovery factors measured in the experiments were also compared with those obtained numerically. Within the limits of the grid resolution and the turbulence model, the agreement was found to be fairly good. In order to simulate the path of debris entering the duct, the trajectories of spherical particles of different sizes introduced at the inlet were determined.

Die neuen Oxobismutate(III) Cs6Bi4O9, K9Bi5O13 und A2Bi4O7 (A = Rb, Cs) / The New Oxobismutates(III) Cs6Bi4O9, K9Bi5O13 and A2Bi4O7 (A = Rb, Cs)

2002 ◽  
Vol 57 (10) ◽  
pp. 1090-1100
Author(s):  
Franziska Emmerling ◽  
Caroline Röhr
Keyword(s):  
Single Crystal ◽  
Crystal Structures ◽  
Alkali Metals ◽  
Mixed Valence ◽  
Three Dimensional ◽  
X Ray Diffraction ◽  
X Ray ◽  
Trigonal Bipyramidal ◽  
Mixed Valence Compound

AbstractThe title compounds were synthesized at a temperature of 700 °C via oxidation of elemental Bi with the hyperoxides AO2 or via reaction of the elemental alkali metals A with Bi2O3. Their crystal structures have been determined by single crystal x-ray diffraction. They are dominated by two possible surroundings of Bi by O, the ψ-trigonal-bipyramidal three (B) and the ψ-tetrahedral four (T) coordination. Cs6Bi4O9 (triclinic, spacegroup P1̄, a = 813.82(12), b = 991.60(14), c = 1213.83(18) pm, α = 103.658(2), β = 93.694(3), γ = 91.662(3)°, Z = 2) contains centrosymmetric chain segmentes [Bi8O18]12- with six three- (T) and two four-coordinated (B) Bi(III) centers. K9Bi5O13 (monoclinic, spacegroup P21/c, a = 1510.98(14), b = 567.59(5), c = 2685.6(2) pm, β = 111.190(2)°, Z = 4) is a mixed valence compound with isolated [BivO4]3- tetrahedra and chains [BiIII4O9]6- of two T and two B coordinated Bi. In the compounds A2Bi4O7 (A = Rb/Cs: monoclinic, C2/c, a = 2037.0(3) / 2130.6(12), b = 1285.5(2) / 1301.9(7), c = 1566.6(2) / 1605.6(9) pm, β = 94.783(3) / 95.725(9)°, Z = 8) ribbons [Bi4O6O2/2]2- are formed, which are condensed to form a three-dimensional framework.

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