Investigation of surface and pseudo-surface acoustic waves excitation and propagation in La3Ga5SiO14 crystal

X-ray diffraction on the La₃Ga₅SiO₁₄ (LGS) crystal modulated by surface (SAW) and pseudo-surface acoustic waves (PSAW) with wavelength of Λ=6 μm was studied using a double axis X-ray diffractometer at the BESSY II synchrotron radiation source. The propagation of SAW and PSAW leads to sinusoidal modulation of the crystal lattice and gives rise to diffraction satellites on the rocking curve, with the intensity and angular divergence between the diffraction satellites depending on the wavelength and amplitude of the crystal lattice acoustic modulation. The analysis of diffraction spectra enables the determination of the amplitude and acoustic wavelengths, and power flow angles of acoustic energy propagation. The investigation of acoustic wave fields showed that PSAW is a flowing back wave.