X-ray analysis of surface and pseudo-surface acoustic waves propagation in disordered La3Ga5SiO14 and ordered Ca3TaGa3Si2O14 crystals

X-ray diffraction on disordered La₃Ga₅SiO₁₄ (LGS) and ordered Ca₃TaGa₃Si₂O₁₄ (CTGS) crystals modulated by surface (SAW) and pseudo-surface acoustic waves (PSAW) with wavelength of A=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, power flow angles of acoustic energy propagation.