Velocity of Sound and Acoustic Attenuation in Pure Gallium Single Crystals

1971 ◽  
Vol 49 (9) ◽  
pp. 1075-1097 ◽  
Author(s):  
K. R. Lyall ◽  
J. F. Cochran
Keyword(s):  
Single Crystals ◽  
Elastic Constants ◽  
Acoustic Waves ◽  
Sound Waves ◽  
Velocity Of Sound ◽  
Velocity Data ◽  
Acoustic Attenuation ◽  
Longitudinal Waves ◽  
Complete Set ◽  
Standing Sound

The velocity of sound for both transverse and longitudinal waves has been measured in single crystals of pure gallium. These velocity data have been used to calculate a complete set of elastic constants for gallium at 273, 77, and 4.2 °K. A survey has also been made of the acoustic attenuation in gallium at approximately 5 MHz over the range 1.5–300 °K. The measurements were made using a transducerless method which utilizes the direct electromagnetic generation of acoustic waves at the surfaces of a metal to excite standing sound waves in a slab-shaped specimen. It is demonstrated that this technique is both convenient and sensitive: changes of 1:106 in the velocity of sound in gallium were found to be readily measurable over the range 1.5–300 °K.

Elastic Properties of L10-Ordered Single Crystals

2007 ◽  
Vol 26-28 ◽  
pp. 221-224 ◽  
Author(s):  
C. Wang ◽  
Katsushi Tanaka ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Single Crystal ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Elastic Properties ◽  
Elastic Constants ◽  
Elastic Anisotropy ◽  
Axial Ratio ◽  
Spectroscopy Technique ◽  
Complete Set

The temperature dependence of single-crystal elastic constants of L10-ordered single-crystals of FePd . A complete set of elastic constants has been determined with the resonance ultrasound spectroscopy technique. The compounds clearly show a tetragonal elastic anisotropy, c11 < c33 and c44 < c66. The temperature dependencies of the anisotropies are not simply explained by the variation of axial ratio (c/a) of the crystal.

scholarly journals Thermomechanical and Photophysical Properties of Crystal-Violet-Dye/H2O Based Dissolutions via the Pulsed Laser Photoacoustic Technique

2014 ◽  
Vol 2014 ◽  
pp. 1-6
Author(s):  
Vicente Torres-Zúñiga ◽  
Rosalba Castañeda-Guzmán ◽  
Santiago J. Pérez-Ruiz ◽  
Omar G. Morales-Saavedra
Keyword(s):  
Crystal Violet ◽  
Speed Of Sound ◽  
Acoustic Waves ◽  
Photophysical Properties ◽  
Accurate Determination ◽  
Pulsed Laser ◽  
Photoacoustic Technique ◽  
Sound Waves ◽  
Acoustic Attenuation

Different thermoelastic parameters, for example, the acoustic attenuation and the speed of sound, are fundamental for instrumental calibration and quantitative characterization of organic-based dissolutions. In this work, these parameters as functions of the concentration of an organic dye (crystal-violet: CV) in distillated water (H2O) based dissolutions are investigated. The speed of sound was measured by the pulsed-laser photoacoustic technique (PLPA), which consists in the generation of acoustic-waves by the optical absorption of pulsed light in a given material (in this case a liquid sample). The thermally generated sound-waves traveling through a fluid are detected with two piezoelectric sensors separated by a known distance. An appropriate processing of the photoacoustic signals allows an adequate data analysis of the generated waves within the system, providing an accurate determination of the speed of sound as function of the dye-concentration. The acoustic attenuation was calculated based on the distance of the two PZT-microphones to an acoustic-source point and performing linear-fitting of the experimental data (RMS-amplitudes) as function of the dye-concentration. An important advantage of the PLPA-method is that it can be implemented with poor or null optical transmitting materials permitting the characterization of the mechanical and concentration/aggregate properties of dissolved organic compounds.

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.

Brillouin scattering studies of simple liquids: O2, N2, CO, CH4

1979 ◽  
Vol 57 (12) ◽  
pp. 2178-2184 ◽  
Author(s):  
M. J. Clouter ◽  
H. Kiefte ◽  
I. E. Morgan
Keyword(s):  
Brillouin Scattering ◽  
Sound Waves ◽  
Saturated Liquid ◽  
Simple Liquids ◽  
Coexistence Line ◽  
Complete Set ◽  
Liquid Vapor

The technique of Brillouin scattering has been used to obtain new velocity and attenuation data for thermal sound waves in liquids O2, N2, CO, and CH4. Measurements of Brillouin shift and linewidth were made along the liquid–vapor coexistence line in each case and, when combined with previously published results, comprise a reasonably complete set of data covering the saturated liquid ranges of all four cryogenic materials. Where possible, comparisons are made with corresponding ultrasonic data.

Attenuation of longitudinal electro-acoustic waves in a plasma

1974 ◽  
Vol 11 (1) ◽  
pp. 37-49
Author(s):  
R. J. Papa ◽  
P. Lindstrom
Keyword(s):  
Dispersion Relation ◽  
Electric Field ◽  
Acoustic Waves ◽  
Collision Frequency ◽  
Wave Dispersion ◽  
Signal Frequency ◽  
Variable Theory ◽  
Longitudinal Waves ◽  
Confluent Hypergeometric Functions ◽  
Linearized Boltzmann Equation

There are several practical situations in partially ionized plasmas when both collisionless (Landau) damping and electron-neutral collisions contribute to the attenuation of longitudinal waves. The longitudinal-wave dispersion relation is derived from Maxwell's equations and the linearized Boltzmann equation, in which electron-neutral collisions are represented by a Bhatnagar–Gross–Krook model that conserves particles locally. (The dispersion relation predicts that, for a given signal frequency ώ), an infinite number of complex wavenumbers kn can exist. Using Fourier–Laplace transform techniques, an integral representation for the electric field of the longitudinal waves is readily derived. Then, using theorems from complex variable theory, a modal expansion of the electric field can be made in terms of an infinite sum of confluent hypergeometric functions, whose arguments are proportional to the complex wavenumbers kn. It is demonstrated numerically that the spatial integral of the square of the electric field amplitude decreases as the electron-neutral collision frequency increases. Also, the amount of energy contained in the first few (lowest) modes, and the coupling between the modes, is examined as a function of plasma frequency, signal frequency and collision frequency.

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