Papers by Author: O.D. Chistyakov

Abstract: The effect of micro-and nanocrystalline structural state on magnetic properties and magnetic entropy (ΔS_M) of Gd is investigated. The marked influence of severe plastic deformation on ΔS_M is demonstrated.

Abstract: Magnetic properties of the hydrides of an intermetallic compound Ho₂Fe₁₄B are studied in the temperature range 78 700 K. The temperature dependencies of magnetization σ (Т) are obtained under continuous control of the hydrogen content in the samples investigated. The dependence of the Curie (T_C) and the spin-reorientation transition (T_SR) temperatures on hydrogen pressure (P) and its concentration (x) are determined. The dependence of hydrogen concentration on pressure at constant temperatures (isotherms x (P)) in the vicinity of T_C and the temperature variation of hydrogen concentration at a constant pressure (isobars x (T)) are investigated.

Abstract: In this work, the structural and magnetic properties of single-phase TbxDyyHoz(Fe,Co)2 (x + y + z = 1) alloys have been investigated by means of X-ray diffraction, 57Fe Mossbauer spectroscopy, magnetization measurements and a standard strain gage technique. The magnetostriction of TbxDyyHoz(Fe,Co)2 was examined against an applied magnetic field up to 10 kOe in 80 - 400 K temperature range. The Co-containing compounds are found to have high values of magnetostrictive susceptibility due to compensation of magnetic anisotropy in both the rare-earth and 3d transition metals sublattices.

Abstract: High-purity compounds R2Fe14B (R = Y, Gd, Tb, Dy, Ho and Er) were prepared by arc melting using rare-earth metals purified by vacuum distillation-sublimation. The compounds R2Fe14B are single-phase and have well-defined directional structure. Nanocrystalline structure was formed by severe plastic deformation of the samples by means of torsion for 5 turns on the Bridgeman anvil under the pressure of 4 GPa at room temperature. The performed investigations of magnetic properties of these compounds allowed us to obtain reliable quantitative data on the intrinsic magnetic parameters, such as saturation magnetization, Curie temperature, the remanent magnetization and coercive force. The enhancement of the remanent magnetization was observed for R2Fe14B in nanocrystalline states compared with the crystalline samples due to the intercrystalline exchange interactions.