INVESTIGATION OF THE BORDONI PEAK IN GOLD AND OTHER F.C.C. METALS,
UPPSALA UNIV (SWEDEN) DEPT OF PHYSICS
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The Bordoni peak has been investigated in the three principal directions bracket 111, bracket 100 and bracket 110 of a single crystal of gold at the frequencies 5, 10, 20 and 45 mcs. The results confirm the previous measurements on single crystals of aluminum, copper and silver. The activation energy and the relaxation frequency differ much from one orientation to the other and the minimum values are obtained when the ultrasonic waves are applied in the bracket 111 direction. The comparison of the Bordoni peak with Zeners single relaxation theory shows that the peak in the bracket 111 direction is due to a single relaxation process while a spectrum of relaxations is responsible for the peak in the other two directions. The activation energy and the relaxation frequency obtained in the bracket 111 direction are found to be very near to those characterizing the single relaxation peak in copper and silver. The values of c sub t Hf sub 0 b4 microns calculated using these activation energies and relaxation frequencies, show that the ratio is invariant in the three metals. This is in agreement with Seegers model and shows that the theory can only be applied when the peak is due to a single relaxation process.