Elastic modules modification and phonon focusing in zinc oxide

Abstract

Despite the direct observations of the acoustic waves focusing in different solids [J. P. Wolfe, Phys. Today 48, 34–40 (1995)], the properties of the phonons’ propagation and possibility of these control have not been studied in hexagonal media. To check this statement [U. V. Zubrytski, Z. Tekhn. Fiz. 67, 59–64 (1997)] and obtain striking demonstrations of drastic changes in the phonon focusing patterns at elastic properties, modification of such solids’ phonon focusing is simulated in zinc oxide grown by the hydrothermal method, in the vapor state at and without doping with lithium, and magnetron sputtering, in this paper. Simulation shows that elastic modules modification within the accuracy of available experimental data causes both sharp increasing of the intensities and defocusing of the individual phonon modes. Quantitative dependences of the effect have been established for bulk acoustic waves in the samples investigated. The findings allow one to elaborate not only the equilibrium but the dynamic method to control selectively both intensities and angular distributions of the acoustic energy fluxes in the crystals and thin layers as well. Besides, the elastic constants recovering from the measuring of the focusing factor can be realized. [Work partially supported by the Belarusian Republican Foundation for Fundamental Research.]

Khatkevich's theory for acoustic axes in 6mm piezoelectric CdS

“…It has been revealed that there are unusual, in comparison with the literature data, properties in STA mode to possess directions of infinite focusing in CdS. New evidences for this finding have been obtained and possibility of the control modification of the phonon fluxes in hexagonal medium has been recently demonstrated by the 3D simulation of the focusing factor in ZnO single crystals and films including ones doped with Li impurity [7, based on 2D data [8]]. To highlight the role of both elastic and piezoelectric anisotropy in the effect, it is supposed in the present paper that this can be effectively accompanied by the acoustic axes investigation method.…”