The Measurement of Overall Elastic Stiffness and Bulk Modulus in Anisotropic Materials: Semiconductors

2009 ◽  
Author(s):  
Mohamed S. Gaith ◽  
I. Alhayek
Keyword(s):  
Bulk Modulus ◽  
Elastic Stiffness ◽  
Quantitative Comparison ◽  
Lattice Constants ◽  
Electro Optic ◽  
Semiconductor Compounds ◽  
Degree Of Anisotropy ◽  
Cubic System ◽  
Tensor Basis ◽  
Norm Ratio

In this study, the correlation between macroscopic and microscopic properties of the II-IV semiconductor compounds ZnX (X = S, Se, Te) is investigated. Based on constructing orthonormal tensor basis elements using the form-invariant expressions, the elastic stiffness for cubic system materials is decomposed into two parts; isotropic (two terms) and anisotropic parts. A scale for measuring the overall elastic stiffness of these compounds is introduced and its correlation with the calculated bulk modulus and lattice constants is analyzed. The overall elastic stiffness is calculated and found to be directly proportional to bulk modulus and inversely proportional to lattice constants. A scale quantitative comparison of the contribution of the anisotropy to the elastic stiffness and to measure the degree of anisotropy in an anisotropic material is proposed using the Norm Ratio Criteria (NRC). It is found that ZnS is the nearest to isotropy (or least anisotropic) while ZnTe is the least isotropic (or nearest to anisotropic) among these compounds. The norm and norm ratios are found to be very useful for selecting suitable materials for electro-optic devices, transducers, modulators, acousto-optic devices.

The Calculation of Stiffness for Semiconductor Components

2009 ◽  
Author(s):  
Mohamed Gaith ◽  
Imad Alhayek
Keyword(s):  
Bulk Modulus ◽  
Elastic Stiffness ◽  
Quantitative Comparison ◽  
Lattice Constants ◽  
Electro Optic ◽  
Semiconductor Compounds ◽  
Cubic System ◽  
Tensor Basis ◽  
Norm Ratio ◽  
Anisotropy Degree

In this study, the correlation between macroscopic and microscopic properties of the II-IV semiconductor compounds CdX (X = S, Se, Te) is investigated. Based on constructing orthonormal tensor basis elements using the form-invariant expressions, the elastic stiffness for cubic system materials is decomposed into two parts; isotropic (two terms) and anisotropic parts. A new scale for measuring the overall elastic stiffness of these compounds is introduced and its correlation with the calculated bulk modulus and lattice constants is analyzed. The overall elastic stiffness is calculated and found to be directly proportional to bulk modulus and inversely proportional to lattice constants. A scale quantitative comparison of the contribution of the anisotropy to the elastic stiffness and to measure the anisotropy degree in an anisotropic material is proposed using the Norm Ratio Criteria (NRC). It is found that CdS is the nearest to isotropy (or least anisotropic) while CdTe is the least near to isotropy (or nearest to anisotropic) among these compounds. The norm and norm ratios are found to be very useful for selecting suitable materials for electro-optic devices, transducers, modulators, acousto-optic devices.

On the Measurement of the Overall Elastic Stiffness and Bulk Modulus in Anisotropic Materials: Semiconductors

2009 ◽  
Author(s):  
Mohamed S. Gaith ◽  
Imad Alhayek
Keyword(s):  
Bulk Modulus ◽  
Elastic Stiffness ◽  
Quantitative Comparison ◽  
Lattice Constants ◽  
Electro Optic ◽  
Semiconductor Compounds ◽  
Cubic System ◽  
Tensor Basis ◽  
Norm Ratio ◽  
Anisotropy Degree

In this study, the correlation between macroscopic and microscopic properties of the II-IV semiconductor compounds CdX (X = S, Se, Te) is investigated. Based on constructing orthonormal tensor basis elements using the form-invariant expressions, the elastic stiffness for cubic system materials is decomposed into two parts; isotropic (two terms) and anisotropic parts. A new scale for measuring the overall elastic stiffness of these compounds is introduced and its correlation with the calculated bulk modulus and lattice constants is analyzed. The overall elastic stiffness is calculated and found to be directly proportional to bulk modulus and inversely proportional to lattice constants. A scale quantitative comparison of the contribution of the anisotropy to the elastic stiffness and to measure the anisotropy degree in an anisotropic material is proposed using the Norm Ratio Criteria (NRC). It is found that CdS is the nearest to isotropy (or least anisotropic) while CdTe is the least near to isotropy (or nearest to anisotropic) among these compounds. The norm and norm ratios are found to be very useful for selecting suitable materials for electro-optic devices, transducers, modulators, acousto-optic devices.

On the Properties of Anisotropic Piezoelectric and Fiber Reinforced Composite Materials

2006 ◽  
Author(s):  
Mohamed Gaith ◽  
Cevdet Akgoz
Keyword(s):  
Composite Materials ◽  
Elastic Fiber ◽  
Physical Property ◽  
Ceramic Materials ◽  
Fiber Reinforced ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite ◽  
Semiconductor Compounds ◽  
Degree Of Anisotropy ◽  
Tensor Basis

A new procedure based on constructing orthonormal tensor basis using the form-invariant expressions which can easily be extended to any tensor of rank n. A new decomposition, which is not in literature, of the stress tensor is presented. An innovational general form and more explicit physical property of the symmetric fourth rank elastic tensors is presented. The new method allows to measure the stiffness and piezoelectricity in the elastic fiber reinforced composite and piezoelectric ceramic materials, respecively, using a proposed norm concept on the crystal scale. This method will allow to investigate the effects of fiber orientaion, number of plies, material properties of matrix and fibers, and degree of anisotropy on the stiffness of the structure. The results are compared with those available in the literature for semiconductor compounds, piezoelectric ceramics and fiber reinforced composite materials.

scholarly journals Comparison of the Solid Solution Properties of Mg-RE (Gd, Dy, Y) Alloys with Atomistic Simulation

2008 ◽  
Vol 2008 ◽  
pp. 1-4 ◽  
Author(s):  
Yurong Wu ◽  
Wangyu Hu
Keyword(s):  
Solid Solution ◽  
Bulk Modulus ◽  
Solid Solubility ◽  
Atomistic Simulation ◽  
Molecular Dynamic Simulations ◽  
Solution Properties ◽  
Dynamic Simulations ◽  
Axis Ratio ◽  
Lattice Constants ◽  
Solution Mechanism

Molecular dynamic simulations have been performed to study the solid solution mechanism of Mg100-xREx (RE=Gd,Dy,Y, x=0.5,1,2,3,4  at.%). The obtained results reveal that the additions of Gd, Dy and Y increase the lattice constants of Mg-RE alloys. Also the axis ratio c/a remains unchanged with increase in temperature, restraining the occurrence of nonbasal slip and twinning. Furthermore, it is confirmed that bulk modulus of Mg alloys can be increased remarkably by adding the Gd, Dy, Y, especially Gd, because the solid solubility of Gd in Mg decrease sharply with temperature in comparison with Dy and Y. Consequently, the addition of the RE can enhance the strength of Mg-based alloys, which is in agreement with the experimental results.

Electronic and elastic properties of AIIB2IIIC4VI defect-chalcopyrite semiconductors

2019 ◽  
Vol 33 (28) ◽  
pp. 1950340 ◽  
Author(s):  
S. Chandra ◽  
Anita Sinha ◽  
V. Kumar
Keyword(s):  
Debye Temperature ◽  
Elastic Properties ◽  
Density Functional ◽  
Elastic Stiffness ◽  
Lattice Constants ◽  
Chalcopyrite Semiconductors ◽  
Principle Density Functional Theory ◽  
Experimental Values ◽  
G Ratio ◽  
First Time

The electronic and elastic properties of [Formula: see text] defect-chalcopyrite semiconductors have been studied using first-principle density functional theory (DFT) calculations. The lattice constants, energy band gap, elastic stiffness constants, bulk modulus, shear modulus, shear anisotropy factor, Young’s modulus, Debye temperature, Poisson’s ratio and B/G ratio have been computed. The values of elastic constants of 14 defect-chalcopyrites and Debye temperature for 18 compounds have been reported for the first time. The obtained results are in reasonable agreement with the experimental values in few cases where experiments are performed and reported values.

First-Principles Calculations of Elastic and Thermodynamic Properties of Cubic CdTe

2011 ◽  
Vol 268-270 ◽  
pp. 886-891
Author(s):  
Ben Hai Yu ◽  
Dong Chen
Keyword(s):  
Experimental Data ◽  
Heat Capacity ◽  
Thermodynamic Properties ◽  
Bulk Modulus ◽  
First Principles ◽  
Debye Model ◽  
First Principles Calculations ◽  
Lattice Constants ◽  
Temperature And Pressure ◽  
The Relationship

the equilibrium lattice constants, elastic and thermodynamic properties of cubic CdTe are systemically investigated at high temperature using the plane-wave pseudopotential method as well as the quasi-harmonic Debye model. The bulk modulus of CdTe are calculated as a function of temperature up to 1000K, the relationship between bulk modulusBand pressure is also obtained. The results gained from this model will provide overall predictions accurately for the temperature and pressure dependence of various quantities such as the bulk modulus, the heat capacity and the thermal expansion coefficient. More over, the dependences between Debye temperature and temperature are also successfully obtained. Our results are compared with the experimental data and discussed in light of previous works.

ELECTRONIC AND ELASTIC PROPERTIES OF MgAl2O4 SPINEL AT HIGH ISOSTATIC PRESSURE: FIRST PRINCIPLE STUDY

2009 ◽  
Vol 23 (06n07) ◽  
pp. 1695-1700 ◽  
Author(s):  
MEILING LI ◽  
FENGJIU SUN ◽  
PING ZHANG
Keyword(s):  
Bulk Modulus ◽  
Elastic Constants ◽  
Nearest Neighbor ◽  
Structural Instability ◽  
High Symmetry ◽  
First Principle ◽  
Lattice Constants ◽  
Bond Lengths ◽  
Energy Gaps ◽  
Internal Parameters

The calculations of mechanic and electronic properties for MgAl 2 O 4 spinel under pressure are presented by first principle. The lattice constants and internal parameters are in good agreement with the available experimental results. The calculations for bulk modulus, elastic constants, energy gaps, bond lengths for the nearest neighbor cation- O anion and their pressure dependence show an increase of bulk modulus, elastic constants, energy gaps in high symmetry and a decrease of cation- O anion bond lengths. A transition from indirect gap material to direct one is found due to applying pressure. Up to 70GPa, there is no sign of structural instability.

scholarly journals Acoustic Vibrational Properties and Fractal Bond Connectivity of Praseodymium Doped Glasses

2000 ◽  
Vol 53 (6) ◽  
pp. 805
Author(s):  
H. B. Senin ◽  
H. A. A. Sidek ◽  
G. A. Saunders
Keyword(s):  
Hydrostatic Pressure ◽  
Bulk Modulus ◽  
Ultrasonic Wave ◽  
Mole Fraction ◽  
Wave Attenuation ◽  
Elastic Stiffness ◽  
Ultrasonic Waves ◽  
Elastic Behaviour ◽  
Doped Glasses ◽  
Two Level Systems

The velocities of longitudinal and shear ultrasonic waves propagated in the (Pr2O3)x(P2O5)1-x glass system, where x is the mole fraction of Pr2O3 and (1 - x) is the mole fraction of P2O5, have been measured as functions of temperature and hydrostatic pressure. The temperature dependencies of the second order elastic stiffness tensor components (SOEC) CS IJ , which have been determined from the velocitydata between 10 and 300 K, show no evidence of phonon mode softening throughout the whole temperature range. The elastic stiffnesses increased monotonically, the usual behaviour associated with the effect of the phonon anharmonicityof atomic vibration. At low temperatures, strong phonon interactions with two-level systems have been observed. The ultrasonic wave attenuation of longitudinal and shear waves is dominated bya broad acoustic loss peak whose height and peak position are frequencydependent. This behaviour is consistent with the presence of thermally activated structural relaxation of the two-level systems in these glasses. The fractal bond connectivity of these glasses, obtained from the elastic stiffnesses determined from ultrasonic wave velocities, has a value between 2.32 to 2.55, indicating that their connectivitytends towards having a threedimensional character. The hydrostatic pressure dependencies of longitudinal ultrasonic waves show a slight increase with pressure. As a consequence, the hydrostatic pressure derivatives ( CS11/ P)P=0 of the elastic stiffness CS11/ and (BS/P)P=0 of the bulk modulus BS of (Pr2O3)x(P2O5)1-x glasses are positive. The bulk modulus increases with pressure, and thus these glasses stiffen under pressure, which is associated with the normal elastic behaviour. The GrÜneisen parameter approach has been used to quantifythe vibrational anharmonicityof the long-wavelength acoustic phonons in these glasses.

scholarly journals A critical assessment of interatomic potentials for modelling lattice defects in forsterite Mg$$_2$$SiO$$_4$$ from 0 to 12 GPa

2021 ◽  
Vol 48 (12) ◽  
Author(s):  
Pierre Hirel ◽  
Jean Furstoss ◽  
Philippe Carrez
Keyword(s):  
Upper Mantle ◽  
Stacking Faults ◽  
Elastic Stiffness ◽  
Elastic Wave Velocity ◽  
Critical Assessment ◽  
Interatomic Potentials ◽  
Planar Defects ◽  
Material Density ◽  
Lattice Constants ◽  
Stacking Fault Energies

AbstractFive different interatomic potentials designed for modelling forsterite Mg$$_2$$ 2 SiO$$_4$$ 4 are compared to ab initio and experimental data. The set of tested properties include lattice constants, material density, elastic wave velocity, elastic stiffness tensor, free surface energies, generalized stacking faults, neutral Frenkel and Schottky defects, in the pressure range $$0-12$$ 0 - 12  GPa relevant to the Earth’s upper mantle. We conclude that all interatomic potentials are reliable and applicable to the study of point defects. Stacking faults are correctly described by the THB1 potential, and qualitatively by the Pedone2006 potential. Other rigid-ion potentials give a poor account of stacking fault energies, and should not be used to model planar defects or dislocations. These results constitute a database on the transferability of rigid-ion potentials, and provide strong physical ground for simulating diffusion, dislocations, or grain boundaries.

STRUCTURAL, ELECTRONIC AND ELASTIC PROPERTIES OF TERNARY ALLOY CoxNi1-xSi2

2013 ◽  
Vol 27 (22) ◽  
pp. 1350142 ◽  
Author(s):  
S. OUCHENE ◽  
M. T. KADRI ◽  
K. BAAOUAGUE ◽  
H. BELKHIR
Keyword(s):  
Shear Modulus ◽  
Bulk Modulus ◽  
Elastic Properties ◽  
Fluorite Structure ◽  
Full Potential ◽  
Generalized Gradient ◽  
Lattice Constants ◽  
Ordered Phases ◽  
Densities Of States ◽  
Binary Compounds

First-principles calculations, by means of the full-potential linearized augmented plane wave (FP-LAPW) method using the generalized gradient approximation (GGA), were carried out for the structural, electronic and elastic properties of transition metals disilicides alloy Co x Ni 1-x Si 2 in the fluorite structure. The composition effect on lattice constants and bulk modulus has been analyzed. The deviations of the lattice constants from Vegard's law and the bulk modulus from linear concentration dependence (LCD) were observed for Co x Ni 1-x Si 2. We also calculated the densities of states for the distorted Co x Ni 1-x Si 2 alloys as well as for the ordered phases CoSi 2 and NiSi 2. Theoretical values of Young's modulus, shear modulus, Poisson's ratio and Debye temperature are estimated from the computed elastic constants. The analysis of the ratio of shear modulus to bulk modulus shows that the alloy is more brittle than the binary compounds. The calculated results are compared with other reported values.

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