Nature of dislocation hysteresis losses and nonlinear effect in lead at high vibration amplitudes
Abstract
The nature of the dislocation hysteresis was established and changes in this hysteresis were determined by investigating the dependence of the dislocation-induced absorption of ultrasound (coefficient ..cap alpha..) on the amplitude of ultrasound epsilon-c/sub 0/ in single crystals of pure lead and of lead containing Tl and Sn impurities. The investigation was carried out in a wide range of epsilon-c/sub 0/ under superconducting transition conditions. In the superconducting (s) state both pure Pb and that doped with T1 exhibited a maximum in the dependence ..cap alpha..(epsilon-c/sub 0/) at high values of epsilon-c/sub 0/; on transition to the normal (n) state this maximum changed to a plateau. This provided a direct proof of a change in the static nature of the dislocation hysteresis to the dynamic process because of an increase in the coefficient of the electron drag of dislocations. Estimates were obtained of the range of lengths of dislocation loops: 2.4 x 10/sup -4/ cm