[en] It was established that experimentally observed anomalous (hysteretic) temperature dependencies of elastic properties of YBa₂Cu₃O_7-δ crystals are related to the hysteretic behavior of the elastic modulus C₃₃₃₃ and are caused temperature-dependent renormalization of force constants of O(4) (apex) oxygen atoms with copper atoms (author)

[en] It is shown that the presence of two superconducting phases in YBa₂Cu₃O_7-8 is a result of predominant contributions of two branches of O(4) apical atom oscillation effective frequency, replacing each other

[en] Is theoretically shown, that the existence two inequivalent metastable conditions of a sublattice of atoms O(4) (depending on temperature of a sample) conducts to changes of elastic constants of a main lattice and to a temperature hysteresis of speed of distribution of a ultrasonic wave. It explains results of experiments on ceramic samples YBa₂Cu₃O_(7-δ), where a hysteresis of longitudinal and cross speeds of a ultra sound as function of temperature in an interval 60-270 K was observed. On the other hand, the thermal hysteresis in these connections is also explained by bistable behaviour of a oxygen sublattice of apex atoms. Therefore a temperature interval of a hysteresis in all cases practically identical. 12 refs., 3 figs

[en] The electrophysical properties of Ge crystals with defect clusters (DC) introduced by irradiation with 660 MeV protons are studied. In order to determine the DC radius and macroscopic formation section the crystals with DC are irradiated with γ-rays of ⁶⁰Co. On the basis of the proposed analysis of the Hall mobility and Hall constant in successively proton- and γ-irradiated crystals the macroscopic formation section (Σ = 0.1 m^-1) and radius (R₀ = 4 x 10^-6 m) of DC are determined. Experimental values of Σ and R₀ are compared with theoretical ones. (author)

No abstract available

[en] The algorithm of a kinetic Monte-Carlo method (KMS) for modeling of formation of clusters of defects in silicon crystals is described. The lattice variant of KMC has been realized. Results of modeling of annealing of selfinterstitial atoms and vacancies in the cascade of displacement are presented and time evolution of concentration of defects has been analyzed. (authors)

[en] It is shown that the existence of two superconducting phases in the compound YBa₂Cu₃O_7-ε is a consequence of alternating (as ε varies) dominant contributions to the BCS pairing from two branches of the effective vibrational frequencies of the apical O(4) atoms, which form a bistable sublattice. The concentration ranges for the existence of these phases are evaluated using percolation theory. The disparity between the critical superconducting transition temperature during cooling and the critical temperature for destruction of the superconducting state during heating of the compound from absolute zero is noted. 20 refs., 4 figs

[en] Charge states of all atoms in the cell of RBa₂Cu₃O_x cuprates (R=Yb, Er, Ho, Y, Gd, Eu, Sm, Nd, Pr; x=6,7) have been determined. The analyses of charge states were performed on the base of calculation the electric field gradient (EFG) with the scope of quantum chemical MO LCAO method taking into account d-orbital. It was founded that for superconducting and non-superconducting cuprates the Cu(2) atom is in 3d⁹ configuration. The charge state of the Cu(1) atom is conformed to the partially filled shell of 3d¹⁰ for the superconducting cuprates and completely filled shell of 3d¹⁰ for the non-superconducting cuprates. The excess hole in the RBa₂Cu₃O₇ resides on the apical O(4) oxygen atom. Removing oxygen atoms from the O(1) position in the cell of RBa₂Cu₃O_x (transition from superconducting to the non-superconducting cuprates) leads to the dramatic change in the character of the chemical bonds of the apical oxygen atom - charge configuration of the O(4) atom from O^-1 to O^-2. The analysis of the filling character of the O(4) orbital and change state of the Ba atom leads to the conclusion that in RBa₂Cu₃O_x cuprates there is hybridization between the apical oxygen O(4) and Ba orbital. (authors). 1 tab., 1 fig., 17 refs

[en] Based on the comparison between theoretical and experimental data on electric field gradient tensor, the distribution of charge states of all atoms over the unit cell of R Ba₂ Cu₃ O_x (x=6,7) (R=Yb, Er, Ho, Y, Gd, Eu, Sm, Nd, Pr) is determined. Variation on the charge states of atoms as a function of ionic radius is considered

[en] Short note