Nanocrystalline vanadium films 7–20 nm thick are obtained by crystallization of amorphous condensates of this metal by heating to a temperature T<60 K. Immediately after completion of the crystallization the critical temperature of the superconducting transition Tc of these films is 3.1–4.3 K. When the films are heated to room temperature in an ultrahigh vacuum the values of Tc decrease by ≈0.4 K. It is shown that this decrease is due, in particular, to relief of the tensile stresses that arise in the films during crystallization.
The magnetoresistance of and Hall effect in polycrystalline α-U in the temperature interval 4.2–77K and transverse magnetic fields B to 4T have been investigated. It is found that below 43K the Hall coefficient RH of α-uranium depends on the magnetic field. The strong temperature dependence of the RH below 43K which is due to three charge-density-wave type transitions is confirmed. Above 43K the Hall coefficient is weakly temperature dependent and is independent of the magnetic field. The magnetoresistance is approximately parabolic and does not exhibit any indications of saturating even in strong fields. The application of the isotropic two-band model made it possible to evaluate qualitatively the dependence of the charge carrier density n and mobility μ on the magnetic field (to 4T) and on the temperature in the interval 4.2–77K. It is shown that charge-density-wave type transitions at T<43K are accompanied by a considerable change in n and μ. It is found that at 4.2K n and μ depend strongly on the magnetic field from 0 to 4T. There is no such dependence at temperatures T⩾50K.
A study is made of the structure, mechanical properties, and electrical resistance of crystalline and pseudoamorphous (obtained by rolling at 300 K by 50 and 90%) titanium nickelide in both the initial state and after annealing to different temperatures in the interval 513–893 K. It is found that the resistivity of polyamorphous Ti–Ni exceeds 200 μΩ⋅cm, falls off monotonically with increasing annealing temperature, and has a minimum in the low-temperature region 4.2–50 K (Tmin=17–19 K). In the temperature interval 4.2–20 K a nonmonotonic temperature dependence of the ultimate strength of polyamorphous Ti–Ni is observed which increases with increasing degree of deformation by rolling of the investigated material. The results are analyzed. It is conjectured that the observed anomaly of the temperature dependences of the ultimate strength and resistivity are due to low-temperature polyamorphism of the pseudoamorphous Ti-Ni in the temperature interval 10–20 K.
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