Appl Phys A (2009) 94: 477–484 DOI 10.1007/s00339-008-4932-1 X-ray diffraction analysis of the surface acoustic wave propagation in langatate crystal D.V. Roshchupkin · A.I. Erko · L. Ortega · D.V. Irzhak Received: 14 January 2008 / Accepted: 9 September 2008 / Published online: 25 October 2008 © Springer-Verlag 2008 Abstract X-ray diffraction on a langatate crystal (La 3 Ga 5.5 Ta 0.5 O 14 , LGT) modulated by a Λ = 12 μm Rayleigh surface acoustic wave (SAW) was studied in a double axis X-ray diffractometer scheme at the BESSY syn- chrotron radiation source. SAW propagation in the crystal causes sinusoidal modulation of the crystal lattice and the appearance of diffraction satellites on the rocking curves, with their number, angular positions, and intensities depend- ing on the wavelength and amplitude of acoustic vibrations of the crystal lattice. Strong absorption of X-ray radiation in LGT enables the observation of the diffraction spectra ex- tinction at certain SAW amplitudes. X-ray diffraction spec- tra analysis makes it possible to determine SAW amplitudes and wavelengths, to measure the power flow angles, and investigate the diffraction divergence in acoustic beam in LGT. PACS 61.05.cp · 77.65.Dq D.V. Roshchupkin ( ) · D.V. Irzhak Institute of Microelectronics Technology RAS, 142432 Chernogolovka, Russia e-mail: rochtch@iptm.ru Fax: +7-495-9628047 A.I. Erko BESSY GmbH, Albert-Einstein Strasse 15, 12489 Berlin, Germany L. Ortega Institut Néel CNRS, 25 Rue des Martyrs, BP 166, 38042 Grenoble cedex 09, France 1 Introduction Development of telecommunication systems based on acous- toelectronic devices and operating with digital signals in a real time mode (mobile phones, radio, pagers, TV, GPS, etc.) requires the application of new piezoelectric materials. Well-known piezoelectric crystals of quartz, LiNbO 3 , and LiTaO 3 do not meet the requirements of new telecommu- nication standards. The appearance of piezoelectric crystals of langasite family, which combine the best acoustic prop- erties of LiNbO 3 (high value of electromechanical coupling coefficient) and quartz (zero temperature coefficient of fre- quency), permits to design miniature acoustoelectronic de- vices with unique properties [1–4]. Another aspect stimulating progress in acoustoelectron- ics is the development of methods which would enable the investigation of excitation and propagation of surface and bulk acoustic waves in crystals. Of greatest interest among these methods are scanning electron microscopy (SEM), X-ray topography, and high-resolution X-ray diffractome- try, which allow visualization of acoustic wave excitation and propagation in the real time mode. SEM in the mode of secondary electron recording can make it possible to vi- sualize surface and bulk, traveling and standing acoustic waves, to study diffraction phenomena in acoustic beams and acoustic wave interaction with crystal structure defects, and to measure acoustic wavelengths and power flow angles [5–10]. However, the SEM method affords only qualitative analysis of acoustic wave propagation and only in piezo- electric materials. Unlike SEM, X-ray diffractometry and topography provide quantitative analysis of acoustic wave field propagation because X-ray radiation is sensitive to si- nusoidal crystal lattice modulation caused by acoustic wave propagation. So X-ray methods can be used to study excita- tion and propagation of acoustic waves both in piezoelec-