INTERACTION OF ACOUSTIC WAVES WITH POLARIZATION WAVES IN FERROELECTRICS

1967 ◽  
Vol 45 (12) ◽  
pp. 3903-3913 ◽  
Author(s):  
V. Dvořák
Keyword(s):  
Elastic Constants ◽  
Acoustic Waves ◽  
Linear Response ◽  
Piezoelectric Effect ◽  
Ultrasonic Attenuation ◽  
Linear Response Theory ◽  
Dielectric Susceptibility ◽  
Direct Relation ◽  
Effective Elastic Constants ◽  
Space Dispersion

An expression for effective elastic constants which control the behavior of acoustic waves interacting with polarization waves in ferroelectrics is derived using the linear response theory. If interactions due to the piezoelectric effect only are taken into account, then the frequency and space dispersion of effective elastic constants are essentially determined by those of the linear dielectric susceptibility. Some consequences of this direct relation between the elastic and dielectric properties of ferroelectrics are discussed for the ultrasonic attenuation and the Brillouin or neutron scattering by acoustic waves.

Elastic Constants of Crystals from Linear-Response Theory

1987 ◽  
Vol 59 (23) ◽  
pp. 2662-2665 ◽  
Author(s):  
Stefano Baroni ◽  
Paolo Giannozzi ◽  
Andrea Testa
Keyword(s):  
Elastic Constants ◽  
Linear Response ◽  
Linear Response Theory ◽  
Response Theory

Effective elastic constants and acoustic properties of single-crystal TiN/NbN superlattices

1992 ◽  
Vol 7 (8) ◽  
pp. 2248-2256 ◽  
Author(s):  
Jin O. Kim ◽  
Jan D. Achenbach ◽  
Meenam Shinn ◽  
Scott A. Barnett
Keyword(s):  
Single Crystal ◽  
Elastic Constants ◽  
Acoustic Waves ◽  
Mass Density ◽  
Surface Acoustic Waves ◽  
Dispersion Curves ◽  
Acoustic Properties ◽  
Tetragonal Symmetry ◽  
Cubic Symmetry ◽  
Effective Elastic Constants

Using the measured elastic constants of TiN and NbN single crystals with cubic symmetry, the effective elastic constants of single-crystal TiN/NbN superlattice films with tetragonal symmetry, namely c11, c12, c13, c33, c44, and c66 have been calculated for various thickness ratios of the layers. Using a line-focus acoustic microscope, measurements of surface acoustic waves (SAWs) have been carried out on single-crystal TiN/NbN superlattice films grown on the (001) plane of cubic crystal MgO substrates. The phase velocities measured as functions of the angle of propagation display the expected anisotropic nature of cubic crystals. Dispersion curves of SAWs propagating along the symmetry axes have been obtained by measuring wave velocities for various film thicknesses and frequencies. The SAW dispersion curves calculated from the effectiveelastic constants and the effective mass density of the superlattice films show very good agreement with experimental results. The results of this paper exhibit no anomalous dependence of the elastic constants on the superlattice period of TiN/NbN superlattices.

Pressure dependent ultrasonic properties of hcp hafnium metal

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Ramanshu P. Singh ◽  
Shakti Yadav ◽  
Giridhar Mishra ◽  
Devraj Singh
Keyword(s):  
Elastic Constants ◽  
Pressure Range ◽  
Room Temperature ◽  
Ultrasonic Attenuation ◽  
Coupling Constants ◽  
Ultrasonic Properties ◽  
Acoustic Coupling ◽  
Third Order Elastic Constants ◽  
The Stability ◽  
The Given

Abstract The elastic and ultrasonic properties have been evaluated at room temperature between the pressure 0.6 and 10.4 GPa for hexagonal closed packed (hcp) hafnium (Hf) metal. The Lennard-Jones potential model has been used to compute the second and third order elastic constants for Hf. The elastic constants have been utilized to calculate the mechanical constants such as Young’s modulus, bulk modulus, shear modulus, Poisson’s ratio, and Zener anisotropy factor for finding the stability and durability of hcp hafnium metal within the chosen pressure range. The second order elastic constants were also used to compute the ultrasonic velocities along unique axis at different angles for the given pressure range. Further thermophysical properties such as specific heat per unit volume and energy density have been estimated at different pressures. Additionally, ultrasonic Grüneisen parameters and acoustic coupling constants have been found out at room temperature. Finally, the ultrasonic attenuation due to phonon–phonon interaction and thermoelastic mechanisms has been investigated for the chosen hafnium metal. The obtained results have been discussed in correlation with available findings for similar types of hcp metals.

Effective Elastic Constants of Fiber-Eutectics and Transformation Particles Composite Ceramic

2010 ◽  
Vol 177 ◽  
pp. 182-185 ◽  
Author(s):  
Bao Feng Li ◽  
Jian Zheng ◽  
Xin Hua Ni ◽  
Ying Chen Ma ◽  
Jing Zhang
Keyword(s):  
Elastic Modulus ◽  
Elastic Constant ◽  
Effective Stress ◽  
Elastic Constants ◽  
Transverse Isotropy ◽  
Analytical Formula ◽  
Composite Ceramic ◽  
Phase Model ◽  
Composite Ceramics ◽  
Effective Elastic Constants

The composite ceramics is composed of fiber-eutectics, transformation particles and matrix particles. First, the recessive expression between the effective stress in fiber-eutectic and the flexibility increment tensor is obtained according to the four-phase model. Second, the analytical formula which contains elastic constant of the fiber-eutectic is obtained applying Taylor’s formula. The eutectic is transverse isotropy, so there are five elastic constants. Third, the effective elastic constants of composite ceramics are predicted. The result shows that the elastic modulus of composite ceramic is reduced with the increase of fibers fraction and fibers diameter.

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