Experimental characterization of the Bordoni peak in copper using 10-50 MHz longitudinal ultrasonic waves

The logarithmic decrement and its associated modulus defect were obtained i n the temperature range 77-300 K, at frequencies 10-50 MHz, in a crystallin e sample deformed at room temperature by 20% along (111). The well develope d Bordoni peaks observed were compared with those obtained in similar sampl es deformed at room temperature between 3 and 10% along (111) and (110), an d a general characterization of the high-frequency Bordoni peak was realize d. The main characteristics of this Bordoni peaks are, firstly, that the ac tivation energy is 0.075 eV and, secondly, that the peak width is 30% great er than a Debye peak. These experimental properties appear to be in reasona ble agreement with the theoretical predictions if kink diffusion in disloca tion lines is considered in the kink pair formation process.