ELECTRONIC, OPTICAL AND MECHANICAL PROPERTIES OF AIIBVI SEMICONDUCTORS

2012 ◽  
Vol 26 (08) ◽  
pp. 1250020 ◽  
Author(s):  
DHEERENDRA SINGH YADAV ◽  
A. S. VERMA
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Energy Gap ◽  
Average Energy ◽  
Compound Semiconductors ◽  
Electronic Polarizability ◽  
Zinc Blende ◽  
Energy Gaps ◽  
Optical And Mechanical Properties ◽  
Good Agreement

The modified dielectric theory of solids is applied to investigate electronic, optical and mechanical properties of A II B VI binary semiconductors ( ZnO, ZnS, ZnSe, ZnTe, CdO, CdS, CdSe, CdTe, HgS, HgSe & HgTe ). The values of homopolar gaps (Eh), heteropolar gaps (Ec) and average energy gaps (Eg) were evaluated for these A II B VI groups of binary semiconductors with Zinc-blende (ZB) structure. The derived values of average energy gap (Eg) were found to be in excellent agreement with the values obtained from the Penn model except ZnO . The electronic polarizability was investigated using Chemla's relation and the values were found to be in a very good agreement with the results obtained from the Clausius–Mossotti relation. The crystal ionicity (fi) was evaluated and the obtained values were compared with the values obtained by different researchers. The evaluated values of crystal ionicity were used to calculate the electronic, optical, mechanical properties such as bulk modulus (B in GPa) cohesive energy or total energy (U in Ryd. electron) and microhardness (H in GPa) of these compound semiconductors. A good agreement has been found between calculated and experimental data.

First-Principles Calculations of the Structural, Electronic, Optical and Mechanical Properties of CdS, CdSe and CdTe

2013 ◽  
Vol 665 ◽  
pp. 302-306 ◽  
Author(s):  
Sheetal Sharma ◽  
Ajay Singh Verma
Keyword(s):  
Experimental Data ◽  
Density Functional ◽  
Full Potential ◽  
Generalized Gradient ◽  
Pressure Derivative ◽  
Functional Theory ◽  
Augmented Plane Wave ◽  
Zinc Blende ◽  
Optical And Mechanical Properties ◽  
Good Agreement

The structural, electronic, optical and elastic properties of zinc-blende compounds (CdX, X = S, Se and Te), were studied using full-potential augmented plane wave plus local orbitals method (FP-LAPW+ lo) within density functional theory, using generalized gradient approximation (GGA). Geometrical optimization of the unit cell (lattice constant, bulk modulus and its pressure derivative) is in good agreement with experimental data. Results for band structures, density of states, and elastic constants (C11, C12 and C44) are presented. We also report our results on optical properties like the complex dielectric functions and the refractive index (n) of these compounds. Our results are in reasonable agreement with the available theoretical and experimental data.

Simulation and prediction of optical characterization of casting (Adamantan-Fulgide) thin films using (CTANNs) approach

2019 ◽  
Vol 33 (11) ◽  
pp. 1950093 ◽  
Author(s):  
A. M. A. EL-Barry ◽  
D. M. Habashy
Keyword(s):  
Experimental Data ◽  
Thin Films ◽  
Back Propagation ◽  
Optical Characterization ◽  
Experimental Information ◽  
Training Algorithm ◽  
Energy Gaps ◽  
Resilient Back Propagation ◽  
Good Agreement

For reinforcement, the photochromic field and the cooperation between the theoretical and experimental branches of physics, the computational, theoretical artificial neural networks (CTANNs) and the resilient back propagation (R[Formula: see text]) training algorithm were used to model optical characterizations of casting (Admantan-Fulgide) thin films with different concentrations. The simulated values of ANN are in good agreement with the experimental data. The model was also used to predict values, which were not included in the training. The high precision of the model has been constructed. Moreover, the concentration dependence of both the energy gaps and Urbach’s tail were, also tested. The capability of the technique to simulate the experimental information with best accuracy and the foretelling of some concentrations which is not involved in the experimental data recommends it to dominate the modeling technique in casting (Admantan-Fulgide) thin films.

DETERMINATION OF VISCOELASTIC PROPERTIES OF THE PERIODONTAL LIGAMENT USING NANOINDENTATION TESTING AND NUMERICAL MODELING

2016 ◽  
Vol 16 (06) ◽  
pp. 1650089 ◽  
Author(s):  
HUIXIANG HUANG ◽  
WENCHENG TANG ◽  
YU YANG ◽  
BIN WU ◽  
BIN YAN
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Periodontal Ligament ◽  
Alveolar Bone ◽  
Spherical Indenter ◽  
Berkovich Indenter ◽  
Zener Model ◽  
Nanoindentation Experiment ◽  
Creep Models ◽  
Good Agreement

Viscoelasticity of the periodontal ligament (PDL) plays an important role in load transmission between tooth and alveolar bone, as well as tooth movement. This paper provides a novel nanoindentation experiment in combination with a rheological model to characterize the viscoelastic mechanical properties of the PDL. Two creep models of the indentation experiments with a Berkovich and a spherical indenter based on Zener model were developed. The hardness and reduced modulus were determined by using the Berkovich indenter. The parameters were identified through curve fittings. The fitting results show that the creep models are both in good agreement with the experimental data. Meanwhile, the models were both validated by comparing the numerical curves for load–depth relationship in loading segment with the corresponding experimental data. It is found that the spherical indenter is more suitable for testing the viscoelastic mechanical properties of the PDL than Berkovich indenter. Hence, the nanoindentation experiment with spherical indenter was simulated to further evaluate the Zener model by finite element analysis. The good agreement between the simulated results and experimental data demonstrates that the Zener model is capable of describing the viscoelastic mechanical behavior of the PDL.

Temperature dependence of the energy gap in semiconductors

1984 ◽  
Vol 62 (3) ◽  
pp. 285-287 ◽  
Author(s):  
A. Manoogian ◽  
J. C. Woolley
Keyword(s):  
Experimental Data ◽  
Vibrational Frequency ◽  
Energy Gap ◽  
Order Approximation ◽  
Approximate Equation ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Energy Gaps ◽  
Dilation Effect ◽  
Interaction Term

It is shown that the equation ΔE = αT2/(T + β), which is commonly used to describe the temperature variation of energy gaps in semiconductors, is a second order approximation of the electron–phonon interaction term in the recently proposed equation ΔE = UTs + Vθ[coth (θ/2T) – 1]. The calculation shows that the parameters α and β of the approximate equation can describe the characteristics of semiconductors only if the relation [Formula: see text] holds, with the validity limited by the magnitude of the existing dilation effect. In this case it is found that β = θ/2 where θ is the effective Einstein vibrational frequency, in temperature units, of the phonon spectrum in the material. A comparison of the two equations when fitted to experimental data is presented and discussed.

Springback Behavior of an Invar Sheet and Its Perforated Form

2006 ◽  
Vol 505-507 ◽  
pp. 781-786
Author(s):  
Yi Che Lee ◽  
Fuh Kuo Chen
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Tensile Tests ◽  
Test Results ◽  
Bending Tests ◽  
Predicted Values ◽  
Springback Behavior ◽  
Good Agreement

The springback behavior of an invar sheet and its perforated form were examined in the present study. The mechanical properties for invar sheet and perforated invar-sheet at elevated temperatures were first obtained from tensile tests. The test results suggest that both invar sheet and perforated invar-sheet have favorable formability at temperature higher than 200oC. An analytical model was also established to predict the springback of the invar sheet and its perforated form under bending conditions at various elevated temperatures. In order to verify the predicted results, the V-bending tests were conducted for the invar sheet at various temperatures ranging from room temperature to 300. The experimental data indicate that the springback decreases with the rise in temperature for both invar sheet and perforated invar-sheet. The good agreement between the experimental data and the predicted values confirms the validity of the proposed theoretical model as well.

Effect of Chain Morphology and Carbon-Nanotube Additives on the Glass Transition Temperature of Polyethylene

2013 ◽  
Vol 23 ◽  
pp. 16-23 ◽  
Author(s):  
S. Herasati ◽  
H.H. Ruan ◽  
Liang Chi Zhang
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Glass Transition ◽  
Carbon Nanotube ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Md Simulation ◽  
Md Simulations ◽  
Crystalline Polymers ◽  
Good Agreement

Glass transition temperature Tg is the most important parameter affecting the mechanical properties of amorphous and semi-crystalline polymers. However, the atomistic origin of glass transition is not yet well understood. Using Polyethylene (PE) as an example, this paper investigates the glass transition temperature Tg of PE with the aid of molecular dynamics (MD) simulation. The effects of PE chain branches, crystallinity and carbon-nanotube (CNT) additives on the glass transition temperature are analyzed. The MD simulations render a good agreement with the relevant experimental data of semi-crystalline PE and show the significant effects of crystallinity and addition of CNTs on Tg.

AB INITIO THERMODYNAMICS OF ZINC-BLENDE ZnS, ZnSe

2011 ◽  
Vol 25 (32) ◽  
pp. 4553-4561 ◽  
Author(s):  
HUAN-YOU WANG ◽  
HUI XU ◽  
JU-YING CAO ◽  
MING-JUN LI
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Constant Pressure ◽  
Local Density ◽  
Linear Thermal Expansion ◽  
Plane Wave Method ◽  
Temperature Range ◽  
Zinc Blende ◽  
Good Agreement

The density function perturbation theory (DFPT) is employed to study the linear thermal expansion and heat capacity at constant pressure (with the quasiharmonic approximation). The calculations are performed using a pseudopotential plane wave method and local density approximation for the exchange-correlation potential. The calculated results of linear thermal expansion coefficient and heat capacity at constant pressure for zinc-blende ZnS , ZnSe are compared with the available experimental data in a wide temperature range. Generally, in low-temperature range, they have good agreement. However, in high-temperature range, due to anharmonic effect and other reasons, lead to larger errors for these properties between the theoretical results and available experimental data.

Structural and Mechanical Properties of RT2Zn20 and RFe2-xCoxZn20(R=Y, Sm; T=Fe, Ru, Os, Co, Rh and Ir)

2011 ◽  
Vol 689 ◽  
pp. 204-210 ◽  
Author(s):  
Yi Chen ◽  
Jiang Shen
Keyword(s):  
Crystal Structure ◽  
Experimental Data ◽  
Mechanical Properties ◽  
Bulk Modulus ◽  
Elastic Constants ◽  
Interatomic Potentials ◽  
Lattice Constants ◽  
Quaternary Compounds ◽  
Cohesive Energies ◽  
Good Agreement

The phase stability, crystal structure and mechanical properties of YT2Zn20 and SmT2Zn20 (T=Fe, Ru, Os, Co, Rh and Ir) compounds have been investigated by using interatomic potentials based on the lattice inversion technique. The calculated lattice constants are in good agreement with the experimental data. The lattice constants increase and Bulk modulus decrease as the transition metal T varies from 3d to 5d. The Y-based compounds with lower energies are more stable than the Sm analogs. Also, the Bulk modulus of YT2Zn20 series are larger than SmT2Zn20 series. Moreover, the mechanical properties of the quaternary compounds YFe2-xCoxZn20 and SmFe2-xCoxZn20­, such as the elastic constants and bulk modulus, have been calculated in this work. The substitution of Co atoms would decrease the cohesive energies and increase the bulk modulus of materials.

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