Attenuation of acoustic waves in Lithium Niobate crystals with impurities

Farkhad Akhmedzhanov , Farhod Juraev

The attenuation of longitudinal and transverse acoustic waves in pure and doped by Mg, Zn, Cu and Cr impurities Lithium Niobate crystals has been investigated. The examined samples LiNbO3 crystals were oriented along the crystallographic axes. Piezoelectric transducers of Lithium Niobate of appropriate cuts are used to excite the longitudinal and the transverse acoustic waves with the frequencies of 0.4-1.8 GHz. The attenuation of acoustic waves was determined by Bragg light diffraction method at the temperatures of 295 and 480 K with accuracy about 5%. The results of these measurements have been shown that the influence of impurities on the attenuation of longitudinal or transversal waves is different. The impurities of Cu, Zn, Mg reduce the decrease of attenuation the longitudinal waves in 1.5-2 times and insignificantly increase of the attenuation of the transversal waves. The obtained results are interpreted in the framework of various mechanisms of attenuation including the electron-phonon and Akhiezer mechanisms. The attenuation of the transversal waves depends also from effective Grunaizen parameter which describes the anisotropy of the phonon-phonon interaction. Moreover the influence of dielectric losses on the attenuation of piezo-active acoustic waves in LiNbO3 crystals is discussed.

Mots clés: acoustic wave; attenuation; crystal; impurity

Domaines: Acoustique [physics.class-ph]

Farkhad Akhmedzhanov, Farhod Juraev. Attenuation of acoustic waves in Lithium Niobate crystals with impurities. Acoustics 2012, Apr 2012, Nantes, France. ⟨hal-00811325⟩