Ultrasonic Attenuation in Calcium Oxide

Abstract

Ultrasonic attenuation studies can be used to characterize material not only after production but during processing as well. The most important causes of ultrasonic attenuation in solids are electron-phonon, phonon-phonon interaction and that due to thermo elastic relaxation. The two dominant processes that will give rise to appreciable ultrasonic attenuation at higher temperature are the phonon-phonon interaction also known as Akhiezer loss and that due to thermo elastic relaxation are observed in calcium oxide crystal. At frequencies of ultrasonic range and at higher temperatures in solids, phonon-phonon interaction mechanism is dominating cause for attenuation. Ultrasonic attenuation due to phonon-phonon interaction (α/f2)p-p and thermo elastic relaxation (α/f2)th are evaluated in Calcium Oxide crystal up to an elevated temperature from 100 K - 1500 K along <100>, <110> and <111> crystallographic directions. Temperature dependence of ultrasonic attenuation along different crystallographic direction reveals some typical characteristic features

Sensitivity of Nanostructured Iron Metal on Ultrasonic Properties

“…and values of lattice sums are: The obtained results of SOEC and TOEC are used to find out the ultrasonic velocities and Grüneisen parameters for longitudinal and shear waves along different crystallographic directions. Those in turn are related to compute acoustic coupling constants and ultrasonic attenuation coefficient [20][21][22][23] as discussed in secondary single crystal structure. The X-ray diffraction (XRD) patterns of iron nanowire arrays specified that most of the iron nanowire arrays have the obvious preferred orientation along the <200> direction [28].…”

“…The secondary objective of the present investigation is to develop a theory for evaluation of ultrasonic attenuation. Mason-Bateman Theory [11,14,15,[19][20][21][22][23][24][25][26][27] is still widely used successfully to study the ultrasonic attenuation at higher temperature (300 K) in solids. It is more reliable theory to study anharmonicity of the crystals as it involves elastic constants directly through acoustic coupling constant "D" in the evaluation of ultrasonic attenuation (α).…”