Determination of ultrasound velocity and attenuation in single crystals by means of x‐ray diffraction

A new method of determination of ultrasound velocity and attenuation in single crystals by means of dynamic x‐ray diffraction is substantiated theoretically and experimentally. The diffractional response in a crystal undergoing stationary or pulsed acoustic excitation is considered. The frequency dependence of the diffraction intensity yields information on ultrasound velocity. Time scanning of the diffraction response under pulsed excitation allows one to determine the attenuation coefficient. Enhancement of the ultrasound‐induced x‐ray diffraction contrast is achieved for high‐frequency acoustic waves, when x‐ray extinction length exceeds the ultrasonic wavelength. The sensitivity and accuracy limitations of the method due to diffraction spreading of the acoustic beam, to the finite thickness of the sample and its inhomogeneity, and to lateral dissipation of the acoustic energy are evaluated. The pertinent experimental data were obtained for silicon and quartz single crystals. The advantages of the prop...