ELASTIC CONSTANTS AND ACOUSTIC WAVE VELOCITIES IN Cd1-xZnxTe MIXED CRYSTALS

2008 ◽  
Vol 22 (12) ◽  
pp. 1221-1229 ◽  
Author(s):  
N. BOUARISSA ◽  
Y. ATIK
Keyword(s):  
Acoustic Wave ◽  
Elastic Constants ◽  
Mixed Crystals ◽  
Bulk Acoustic Wave ◽  
Virtual Crystal Approximation ◽  
Wave Speeds ◽  
Wave Velocities ◽  
Zinc Blende ◽  
Compositional Disorder ◽  
Zinc Blende Structure

Based on the pseudopotential scheme under the virtual crystal approximation that takes into account the effect of compositional disorder combined with the bond-orbital model of Harrison, the results of calculations of elastic constants and surface and bulk acoustic wave speeds of Cd 1-x Zn x Te mixed crystals in the zinc-blende structure are presented. The agreement between our results and known data, which are only available for CdTe and ZnTe is found to be reasonable.

Microhardness, phase transition, acoustic wave velocities and melting temperature of AlxGa1−xSb

2018 ◽  
Vol 32 (20) ◽  
pp. 1850210 ◽  
Author(s):  
O. A. Al-Hagan ◽  
H. Algarni ◽  
N. Bouarissa ◽  
M. Ajmal Khan ◽  
T. F. Alhuwaymel
Keyword(s):  
Acoustic Wave ◽  
Melting Temperature ◽  
Composition Dependence ◽  
Ternary Alloys ◽  
Virtual Crystal Approximation ◽  
Al Content ◽  
Wave Velocities ◽  
Good Accord ◽  
Compositional Disorder ◽  
Pseudopotential Approach

The band structure of Al[Formula: see text]Ga[Formula: see text]Sb semiconducting ternary alloys and their related properties such as elastic constants, microhardness, transition pressure to the first phase, acoustic wave velocities and melting temperature have been investigated. The calculations are performed using a pseudopotential approach within the virtual crystal approximation which includes the effect of compositional disorder as an effective potential. Generally, our results are found to be in good accord with the experimental results. The composition dependence of all features of interest showed a monotonic behavior and suggests that the stiffness, hardness and structural stability becomes better in Al[Formula: see text]Ga[Formula: see text]Sb for higher Al concentrations. The bulk sound speeds and melting temperature are found to become larger when increasing the Al content.

scholarly journals Theoretical investigation of acoustic wave velocity of aluminum phosphide under pressure

2019 ◽  
Vol 7 (1) ◽  
pp. 3
Author(s):  
Salah Daoud ◽  
Abdelhakim Latreche ◽  
Pawan Kumar Saini
Keyword(s):  
Acoustic Wave ◽  
Wave Velocity ◽  
Elastic Constants ◽  
Structural Parameters ◽  
Theoretical Data ◽  
Aluminum Phosphide ◽  
Semiconducting Material ◽  
Wave Velocities ◽  
Knoop Microhardness ◽  
Good Agreement

The bulk and surface acoustic wave velocities of Aluminum phosphide (AlP) semiconducting material under pressure up to 9.5 GPa were studied. The structural parameters and the elastic constants used in this work are taken from our previous paper published in J. Optoelec-tron. Adv. M. 16, 207 (2014). The results obtained at zero-pressure are analyzed and compared with other data of the literature. In addition, the acoustic Grüneisen parameter and the Vickers and Knoop microhardness are predicted and analyzed in detail. Our calculated results are in good agreement with the experimental and other theoretical data of literature.   

The mathematical modeling for bulk acoustic wave propagation velocities in transversely isotropic piezoelectric materials

2015 ◽  
Vol 22 (4) ◽  
pp. 823-836 ◽  
Author(s):  
Abo-el-nour N Abd-alladan ◽  
Abdelmonam M Hamdan ◽  
Adel A Almarashi ◽  
Antonio Battista
Keyword(s):  
Acoustic Wave ◽  
Acoustic Waves ◽  
Piezoelectric Effect ◽  
Piezoelectric Materials ◽  
Transversely Isotropic ◽  
Bulk Acoustic Wave ◽  
Acoustic Wave Propagation ◽  
Wave Velocities ◽  
Saw Devices ◽  
Propagation Velocities

The objective of this paper is to study the bulk acoustic wave (BAW) propagation velocities in transversely isotropic piezoelectric materials, aluminum nitride, zinc oxide, cadmium sulfide and cadmium selenide. The bulk acoustic wave velocities are computed for each direction by solving the Christoffel’s equation based on the theory of acoustic waves in anisotropic solids exhibiting piezoelectricity. These values are calculated numerically and implemented on a computer by Bisection Method Iterations Technique (BMIT). The modification of the bulk acoustic wave velocities caused by the piezoelectric effect are graphically compared with the velocities in the corresponding non-piezoelectric materials. The results obtained in this study can be applied to signal processing, sound systems and wireless communication in addition to the improvement of surface acoustic wave (SAW) devices and military defense equipment.

Beryllium Effect on the Energy Band Gaps and the Electronic Charge Density of the Alloy (Be, Cd) Se

2019 ◽  
Vol 297 ◽  
pp. 131-142
Author(s):  
Hadjer Saheb ◽  
Abderrachid Bechiri
Keyword(s):  
Charge Density ◽  
Electronic Band Structure ◽  
Electronic Charge ◽  
Electronic Charge Density ◽  
Virtual Crystal Approximation ◽  
Electronic Band ◽  
Empirical Pseudopotential Method ◽  
Zinc Blende ◽  
Disorder Effect ◽  
Zinc Blende Structure

In the present study, we have computed the electronic band structure and electronic charge density of the alloy (Be, Cd)Se in the zinc-blende structure; using the local Empirical Pseudopotential Method (EPM), which takes into account the disorder effect into the Virtual Crystal Approximation (VCA) by introducing an effective potential disorder. The obtained results show a reasonable agreement with the available experimental data. Detailed plots of the valence charge distribution along the [111] direction and in the (110) plane are also presented and discussed.

Acoustic waves I

2004 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Acoustic Wave ◽  
Elastic Constants ◽  
Acoustic Waves ◽  
Shear Waves ◽  
Plane Waves ◽  
Volume Element ◽  
Longitudinal Waves ◽  
Stress Gradients ◽  
Wave Velocities ◽  
Wave Normal

In this chapter we treat plane waves specified by a wave normal and a particle motion vector . Two types of waves, longitudinal waves and shear waves, are observed in solids. For low symmetry directions, there are generally three different waves with the same wave normal, a longitudinal wave and two shear waves. The particle motions in the three waves are perpendicular to one another. Only longitudinal waves are present in liquids because of their inability to support shear stresses. The transverse waves are strongly absorbed. Acoustic wave velocities (v) are controlled by elastic constants (c) and density (ρ). For a stiff ceramic (c ∼ 5 × 1011 N/m2) and density (ρ ∼ 5 g/cm3 = 5000 kg/m3), the wave velocity is about 104 m/s. For low frequency vibrations near 1 kHz the wavelength λ is about 10 m. The shortest wavelengths are around 1 nm and correspond to infrared vibrations of 1013 Hz. Acoustic wave velocities for polycrystalline alkali metals are plotted in Fig. 23.2. Longitudinal waves travel at about twice the speed of transverse shear waves since c11 > c44. Sound is transmitted faster in light metals like Li which have shorter, stronger bonds and lower density than heavy alkali atoms like Cs. The tensor relation between velocity and elastic constants is derived using Newton’s Laws and the differential volume element shown in Fig. 23.3(a). The volume is equal to (δZ1) (δZ2) (δZ3). Acoustic waves are characterized by regions of compression and rarefaction because of the periodic particle displacements associated with the wave. These displacements are caused by the inhomogeneous stresses emanating from the source of the sound. In tensor form the components of the stress gradient are ∂Xij/∂Zk and will include both tensile stress gradients and shear stress gradients, as pictured in Fig. 23.3(b). The force F acting on the volume element is calculated by multiplying the stress components by the area of the faces on which the force acts.

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