Ultrasonic studies on a low temperature attenuation peak in L-arginine phosphatemonohydrate single crystal

The ultrasonic properties at different frequencies of pure LAP single crystals with two directions were measured over the temperature range of 160–300 K. A pronounced ultrasonic attenuation peak was found in both directions. The frequency dependence of the peak indicated that it is caused by the resonant damping of dislocations. The peak was well fitted on using the G–K–L string vibration theory, with the assumption that the relaxation time increases exponentially with temperature. It was found that the damping properties of dislocations in pure LAP single crystals have a slight dependence on the crystallographic direction.