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.

A five-component crystal of lanthanum-gallium silicate family Ca3TaGa3Si2O14 (CTGS) was grown by the Czochralski method. The CTGS crystal, like langasite crystals La3Ga5SiO14, possesses unique temperature properties and the fewer number of the Ga atoms in the unit cell makes the density much lower and, consequently, increases the velocity of acoustic wave propagation. The unit cell parameters were determined by the powder diffraction technique. The defects in the CTGS crystal structure were studied by X-ray topography which enables the visualization of growth banding characteristics of crystal grown by Czochralski method. Surface acoustic wave (SAW) propagation in the CTGS crystal was investigated by the high-resolution X-ray diffraction method. The velocities of propagation and power flow angles of SAW in the Yand X-cuts of the CTGS crystal were determined from the X-ray diffraction spectra.

A new promising piezoelectric material Ca 3 TaGa 3 Si 2 O 14 (CTGS) has been grown using the Czochralski method. Its unit-cell parameters have been determined by means of the X-ray phase analysis method. The X-ray diffractometry method was used to study the crystal acoustic properties; the velocities of surface acoustic wave propagation were measured for the first time and the power flow angles were determined.

This paper reports a scanning electron microscope study of the interaction between the surface acoustic waves and regular domain structures in LiNbO3 crystals. The regular domain structures in LiNbO3 crystals were formed by the method of the thermo-electric treatment after growth. We investigated two modes of interaction: the surface-acoustic-waves propagate along and across the regular domain structures. It is shown that the regular domain structures in the first case can be used as an acoustical wave-guide, because the power-flow vector of the surface acoustic waves has the direction along the domain structure. Also we observed that the surface acoustic wave inverts the voltage contrast of the image in the scanning electron microscope by pi during the process of the propagation across the domain walls.