scholarly journals Modeling the Bulk and Nanometric Dielectric Functions of Au and Ag

2021 ◽  
Author(s):  
Brahim Ait Hammou ◽  
Abdelhamid El Kaaouachi ◽  
Abdellatif El Oujdi ◽  
Adil Echchelh ◽  
Said Dlimi ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Function ◽  
Imaginary Part ◽  
Complex Number ◽  
Theoretical Models ◽  
Electronic Transitions ◽  
Experimental Measurements ◽  
Mathematical Functions ◽  
Lorentz Theory ◽  
Critical Model

In this work, we model the dielectric functions of gold (Au) and silver (Ag) which are typically used in photonics and plasmonics. The modeling has been performed on Au and Ag in bulk and in nanometric states. The dielectric function is presented as a complex number with a real part and an imaginary part. First, we will model the experimental measurements of the dielectric constant as a function of the pulsation ω by appropriate mathematical functions in an explicit way. In the second part we will highlight the contributions to the dielectric constant value due to intraband and interband electronic transitions. In the last part of this work we model the dielectric constant of these metals in the nanometric state using several complex theoretical models such as the Drude Lorentz theory, the Drude two-point critical model, and the Drude three-point critical model. We shall comment on which model fits the experimental dielectric function best over a range of pulsation.

Electric Field Effect on the Imaginary Part of the Dielectric Function in Highly Anisotropic Crystals

1974 ◽  
Vol 36 (1) ◽  
pp. 179-186 ◽  
Author(s):  
Yoshiro Sasaki ◽  
Chihiro Hamaguchi ◽  
Akihiro Morotani ◽  
Junkichi Nakai
Keyword(s):  
Electric Field ◽  
Dielectric Function ◽  
Imaginary Part ◽  
Field Effect ◽  
Electric Field Effect

scholarly journals Temperature dependence of hardness prediction for high-temperature structural ceramics and their composites

2021 ◽  
Vol 10 (1) ◽  
pp. 586-595
Author(s):  
Ruzhuan Wang ◽  
Dingyu Li ◽  
Weiguo Li
Keyword(s):  
High Temperature ◽  
Temperature Dependence ◽  
Material Design ◽  
Theoretical Models ◽  
Ceramic Composites ◽  
Basic Material ◽  
Experimental Measurements ◽  
Control Mechanisms ◽  
Oxide Ceramics ◽  
Structural Ceramics

Abstract Hardness is one of the important mechanical properties of high-temperature structural ceramics and their composites. In spite of the extensive use of the materials in high-temperature applications, there are few theoretical models for analyzing their temperature-dependent hardness. To fill this gap in the available literature, this work is focused on developing novel theoretical models for the temperature dependence of the hardness of the ceramics and their composites. The proposed model is just expressed in terms of some basic material parameters including Young’s modulus, melting points, and critical damage size corresponding to plastic deformation, which has no fitting parameters, thereby being simple for materials scientists and engineers to use in the material design. The model predictions for the temperature dependence of hardness of some oxide ceramics, non-oxide ceramics, ceramic–ceramic composites, diamond–ceramic composites, and ceramic-based cermet are presented, and excellent agreements with the experimental measurements are shown. Compared with the experimental measurements, the developed model can effectively save the cost when applied in the material design, which could be used to predict at any targeted temperature. Furthermore, the models could be used to determine the underlying control mechanisms of the temperature dependence of the hardness of the materials.

scholarly journals Preparation and characterization of polyani-line/polyvinyl alcohol nanocomposite by laser irradiation

2017 ◽  
Vol 6 (4) ◽  
pp. 77
Author(s):  
N A M Shahin ◽  
S Abd El Mongy ◽  
R Kamal ◽  
A B El- Bially ◽  
A A Shabaka ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Relaxation Time ◽  
Polyvinyl Alcohol ◽  
Laser Irradiation ◽  
Imaginary Part ◽  
Electronic Transition ◽  
X Ray Diffraction ◽  
X Ray ◽  
Amorphous Nature

Polyaniline (PANI) - Polyvinyl alcohol (PVA) nanocomposite were prepared using laser irradiation method. X-ray diffraction results showed that, (PANI/PVA) nanocomposite exhibited amorphous nature of polymer. The electronic transition will be studied using Ultraviolet-Visible spectrometer (UV-Vis). The real part of dielectric constant (έ) and imaginary part (ε") were studied. Also, the relaxation time was calculated.

scholarly journals Bioinspired aerofoil adaptations: the next steps for theoretical models

2019 ◽  
Vol 377 (2159) ◽  
pp. 20190070 ◽  
Author(s):  
Lorna J. Ayton
Keyword(s):  
Experimental Data ◽  
Theoretical Models ◽  
Theoretical Modelling ◽  
Experimental Measurements ◽  
Far Field ◽  
Acoustic Analogy ◽  
Trailing Edge ◽  
Trailing Edge Noise ◽  
Theoretical Predictions ◽  
Field Noise

The extended introduction in this paper reviews the theoretical modelling of leading- and trailing-edge noise, various bioinspired aerofoil adaptations to both the leading and trailing edges of blades, and how these adaptations aid in the reduction of aerofoil–turbulence interaction noise. Attention is given to the agreement between current theoretical predictions and experimental measurements, in particular, for turbulent interactions at the trailing edge of an aerofoil. Where there is a poor agreement between theoretical models and experimental data the features neglected from the theoretical models are discussed. Notably, it is known that theoretical predictions for porous trailing-edge adaptations do not agree well with experimental measurements. Previous works propose the reason for this: theoretical models do not account for surface roughness due to the porous material and thus omit a key noise source. The remainder of this paper, therefore, presents an analytical model, based upon the acoustic analogy, to predict the far-field noise due to a rough surface at the trailing edge of an aerofoil. Unlike previous roughness noise models which focus on roughness over an infinite wall, the model presented here includes diffraction by a sharp edge. The new results are seen to be in better agreement with experimental data than previous models which neglect diffraction by an edge. This new model could then be used to improve theoretical predictions for far-field noise generated by turbulent interactions with a (rough) porous trailing edge. This article is part of the theme issue ‘Frontiers of aeroacoustics research: theory, computation and experiment’.

Measurement of the dielectric function spectra of low dielectric constant using the spectroscopic ellipsometry

2003 ◽  
Author(s):  
Masahiro Horie ◽  
Kamil Postava ◽  
Tomuo Yamaguchi ◽  
Kumiko Akashika ◽  
Hideki Hayashi ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Function ◽  
Spectroscopic Ellipsometry ◽  
Low Dielectric Constant ◽  
Low Dielectric

On the Axisymmetric Response of a Damaged Flexible Pipe

2014 ◽  
Author(s):  
José Renato M. de Sousa ◽  
Carlos Magluta ◽  
Ney Roitman ◽  
George C. Campello
Keyword(s):  
Finite Element ◽  
Analytical Model ◽  
Load Capacity ◽  
High Stress ◽  
Experimental Tests ◽  
Theoretical Models ◽  
Experimental Measurements ◽  
Fe Model ◽  
Flexible Pipe ◽  
High Stress Concentration

This work focuses on the structural analysis of a damaged 9.13″ flexible pipe to pure and combined axisymmetric loads. A set of experimental tests was carried out considering one up to ten broken wires in the outer tensile armor of the pipe and the results obtained are compared to those provided by a previously presented finite element (FE) model and a traditional analytical model. In the experimental tests, the pipe was firstly subjected to pure tension and, then, the responses to clockwise and anti-clockwise torsion superimposed with tension were investigated. In these tests, the induced strains in the outer armor were measured. Moreover, the axial elongation of the pipe was monitored when the pipe is subjected to tension, whilst the twist of the pipe was measured when torsion is imposed. The experimental results pointed to a slight decrease in the stiffness of the pipe with the increasing number of broken wires and, furthermore, a redistribution of forces among the intact wires of the damaged layer with high stress concentration in the wires close to the damaged ones. Both theoretical models captured these features, but, while the results obtained with the FE model agreed well with the experimental measurements, the traditional analytical model presented non-conservative results. Finally, the results obtained are employed to estimate the load capacity of the pipe.

Non Destructive Optical Analysis of Implanted Layers in GaAs by Raman Scattering and Spectroscopic Ellipsometry

1982 ◽  
Vol 14 ◽  
Author(s):  
Joseph Biellmann ◽  
Bernard Prevot ◽  
Claude Schwab ◽  
Jean-Bernard Theeten ◽  
Marko Erman
Keyword(s):  
Raman Scattering ◽  
Dielectric Function ◽  
Imaginary Part ◽  
Depth Profile ◽  
Spectroscopic Ellipsometry ◽  
Intensity Ratio ◽  
Optical Analysis ◽  
Lattice Potential ◽  
Destructive Analysis ◽  
Non Destructive

ABSTRACTNon destructive analysis by Raman Scattering (RS) and Spectroscopic Ellipsometry (SE) is demonstrated on B+- and Se+ shallow implanted GaAs. Qualitative informations are obtained from 1st and 2nd order RS spectra. The former are analysed using the intensity ratio of the T0 and L0 modes, which defines a lattice potential perfection scale. The SE analysis of the E1, E1 +Δ1 structure in the imaginary part of the dielectric function confirms the RS results and its multilayer analysis yields the depth profile of the implanted ions.

Computation of the Porous Silicon Dielectric Function in the Supercell Model and Comparison with Experiment

1999 ◽  
Vol 579 ◽  
Author(s):  
J. Tagüeeña-Martínez ◽  
Y.G. Rubo ◽  
M. Beltrán ◽  
C. Wang ◽  
M. Cruz
Keyword(s):  
Porous Silicon ◽  
Dielectric Function ◽  
Imaginary Part ◽  
Absorption Edge ◽  
Tight Binding ◽  
Pore Morphology ◽  
Hydrogen Atoms ◽  
Comparison With Experiment ◽  
Supercell Model

ABSTRACTWe present the results for the imaginary part of the dielectric function of porous silicon, which were obtained with the tight-binding 128–atom supercell model for different porosities. The supercells have been chosen to allow the interconnection of the Si skeleton. We have analyzed also the effects of pore morphology. We have found that, at a fixed porosity, the developing of the surface, resulting in the increase of saturating hydrogen atoms, leads to a noticeable blueshift of the absorption edge.

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