An experimental study of Young's modulus $E$ and the internal friction $Q^{-1}$ in Dy polycrystals of varying purity was carried out in the 4.2-350 K temperature range. A giant maximum of internal friction was found in the region of low temperatures (at T = 37 K and $\nu$ = 2030 Hz the internal friction is $2,15\cdot 10^{-2}$). The internal friction maximum observed in the paramagnetic temperature region had a dislocational origin. The activation energy $E_a$ of this process was 0.38 $\pm 0,05$ eV and the frequency factor $\tau_0= 2.9\cdot 10^{-11}$ s.
Department of Molecular Physics and Physical Measurements, Faculty of Physics, Moscow State University, Leninskie Gory, Moscow, 119992, Russia
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