Ultrasonic investigation of sandwich single crystals designed for studies of dislocation resonance damping

A novel sandwich single crystal (SSC) technique has been designed for improved MHz-pulse-echo investigations of dislocation damping. In the present SSC the high purity Cu crystal to be investigated is epitaxially overgrown by a buffer crystal doped with 200 ppm Mn. The buffer avoids interference between ultrasonic transducer and sample by shielding the investigated dislocation structure against stresses caused e.g., by different thermal expansion of the quartz transducer. The frequency dependence of dislocation resonance damping measured on the SSC has been analyzed and compared with measurements on normal single crystalline samples of high purity Cu and Cu doped with 200 ppm Mn.