Anelastic Effects in the β-Phase of Niobium Hydride

Abstract

The attenuation of low‐frequency (≈︁ 103 Hz) sound vibrations and the elastic modulus dispersion in mono‐ and polycrystalline niobium hydrides with hydrogen contents H/Nb ≈︁ 0.8 are investigated over the temperature range from 160 to 450 K. Sound attenuation and elastic modulus dispersion are anomalously high (Q−1 ≈︁ 0.14, ΔG/G0 ≈︁ 0.5) in the region of orthorhombic β‐phase. Such a strong anelastic relaxation is observed only during the motion of Bloch walls in ferromagnets. Such characteristics of the spectrum as a) sharp attenuation decrease outside the β‐phase region; b) a wide range of relaxation times in monocrystalline samples and its narrowing to a single spectral line in polycrystals;; c) a strong dependence of relaxation rate upon hydrogen concentration (sceeding the fourth power) show that the anelastic relaxation in the β‐phase of niobium hydride is caused by domain boundary motion under the action of elastic stresses.

Acoustic investigations of the ZrV2–H system

“…In references [17,18] dedicated to the study of some binary Me-H systems, earlier unknown phases were successfully detected, and the critical dynamics of soft mode-type accompanying the transition to the long-periodical structure were also investigated.…”

“…The same electrode, included in the oscillatory circuit of a high-frequency generator (ν ∼ 100 MHz), was used as detector. Using the feedback system, a continuous excitation of sample oscillations was provided at a natural frequency, as it was described in [7].…”

Features of Thermoplastic Deformations of Quasi-Anisotropic 2D Layers of Indium

“…where G is the shear modulus, b is the Burgers vector, d-the interplanar distance [14]. The opportunity to overcome these barriers for edge dislocations − ∼ ⋅ 21 1.2 10 J P E at low temperatures in indium is almost impossible.…”

“…The opportunity to overcome these barriers for edge dislocations − ∼ ⋅ 21 1.2 10 J P E at low temperatures in indium is almost impossible. However, the kinks formed at the dislocations during both the deformation process and at the dislocation origination when cultivating the layers, can overcome the barrier due to the phenomenon of tunnelling [14]. It is known, that the process of moving kinks 'under barrier' can be considered as solitons tunnelling, since the kinks at dislocations are associated with these separated nonlinear waves which interact with potential characteristics of the lattice [14].…”

“…However, the kinks formed at the dislocations during both the deformation process and at the dislocation origination when cultivating the layers, can overcome the barrier due to the phenomenon of tunnelling [14]. It is known, that the process of moving kinks 'under barrier' can be considered as solitons tunnelling, since the kinks at dislocations are associated with these separated nonlinear waves which interact with potential characteristics of the lattice [14]. As it follows from quantum mechanics, the tunnelling effect will be significant if the correlation takes place: -the mass of the kinksoliton (assuming that the mass of the soliton is half the mass of the proton) [14,15].…”