Studying Acoustic-Wave Fields in Langasite-Family Crystals Using the BESSY II Synchrotron Radiation Source

The process of the excitation and propagation of pseudosurface acoustic waves in crystals of the langasite family is studied via X-ray diffractometry for the first time. The investigations are carried out using the BESSY II synchrotron radiation source in the double-crystal X-ray diffractometer scheme. The process of pseudosurface acoustic wave propagation is studied based on an analysis of the diffraction spectra of acoustically modulated crystals. Both the velocities of the pseudosurface acoustic waves and the power flow angles of the acoustic energy are measured for the first time. The pseudosurface acoustic wave is shown to be flowing. Surface and pseudosurface acoustic waves generated by an interdigital transducer in the Z cut of a La3Ga5.5Ta0.5O14 crystal are compared.