The structural and magnetic characteristics of phase transformations in Tb(Fe1 − x Al x )2 alloys with concentrations x = 0−0.9 have been measured in the temperature range from 90 to 450 K. The temperature dependences of the hyperfine magnetic fields for each of local configurations of the nearest environment of iron atoms upon substitution of aluminum atoms for iron atoms have been found using Mössbauer spectroscopy.

The Nd(Fe0.9Al0.1)2 alloy was synthesized at a high pressure. The crystalline structural characteristics of the alloy were determined. Hyperfine magnetic interactions in the range from 90 to 450 K were investigated using Mössbauer spectroscopy and the temperature dependences of the magnetic characteristics of the alloy were established depending on the configuration of the nearest environment of the iron atom.

The alloys Nd(Fe 1 − x Al x ) 2 (at concentrations x = 0–1) are synthesized under high pressure. The phase composition and crystallographic structural characteristics of the alloys are determined as a function of the concentration x . Mössbauer spectroscopy is used to study hyperfine magnetic interactions in the temperature range from 90 to 400 K. The temperature and concentration dependences of the magnetic characteristics of the alloys are determined.

The Pr(Fe1 − x Al x )2 alloys with concentrations x = 0–1 have been synthesized under a high pressure. The phase composition and lattice parameters (a and c) have been determined as a function of x. The magnetic and Mössbauer measurements have been performed at T = 90–400 K. It has been established that the Curie temperatures of alloys linearly depend on their composition.

The structural transformations and magnetic phase transitions in the quasibinary system Y(Fe 1 − x Al x ) 2 have been investigated by Mössbauer spectroscopy, X-ray diffractometry, and magnetic measurements of polycrystals.

Mössbauer spectra of copper ferrites CuGa x Al2x Fe2 − 3x O4 (x = 0.3, 0.4, 0.5) have been measured at temperatures in the range from 90 to 295 K. The degree of disturbance of long-range magnetic order has been determined as a function of the temperature. The Curie temperature has been found for the composition with x = 0.5, and the dependence of the Curie temperature on the concentration of the nonmagnetic impurity has been constructed.

The compounds Tb 0.35 Dy 0.45 Er 0.2 Fe 2 − x Co x (0 ≤ x ≤ 2) are synthesized in both polycrystalline and single-crystal states. The composition of the new multicomponent alloys with compensated magnetic anisotropy is calculated in the framework of the single-ion magnetic anisotropy model with allowance for the data on the temperature dependences of the magnetic anisotropy constants for R Fe 2 single crystals. The synthesized compounds are characterized using metallographic, chemical, X-ray diffraction, and thermomagnetic methods. A combined analysis of the magnetic and magnetoelastic properties is also carried out. It is established that the high magnetostriction characteristics of the rare-earth intermetallic compounds Tb 0.35 Dy 0.45 Er 0.2 Fe 2 − x Co x with a structure of Laves phases are observed in the region of the spin-reorientational phase transition whose temperature can be varied by properly choosing the Co content. It is found that, in the room-temperature region, the magnetic susceptibility ( d λ/ dH ) of the composition with x = 1.3 reaches levels in excess of the value of d λ/ dH for terphenol D due to the compensation of magnetic anisotropy.

Mössbauer spectra of the CuGa x Al2x Fe2 − 3x O4 system (x = 0.1, 0.2, 0.3, 0.4, 0.5) have been studied at a temperature of 295 K. The results obtained are compared with Mössbauer data for the CuGa x Al x Fe2−2x O4 system. It is established that the hyperfine magnetic fields H B (for octahedral sites) and H A (for tetrahedral sites) for ferrites in both systems with ferrimagnetic ordering decrease linearly depending on the total number of nonmagnetic ions in octahedral and tetrahedral sites of the two systems.

A complex study of the phase composition, atomic and crystalline structure, magnetic properties, and superfine interactions of the Tb0.3Dy0.7Fe2 − x Co x system alloys (x = 0−1.3) has been performed. The synthesized alloys are isotypic with the cubic Laves phase (C15 type), their cell parameter monotonically decreases with an increase in the Co content and, hence, the saturation magnetostriction also does. However, the concentration dependences of the Curie temperature, saturation magnetization, and superfine magnetic field strength measured in the Mössbauer experiment display a nonmonotonic (dome-like) character.

The x-ray structural properties of samples in the CuGa x Al x Fe 2−2 x O 4 ( x = 0−0.7) and CuGa x Al 2 x Fe 2−3 x O 4 ( x = 0−0.5) systems are studied. It is found that magnetic ordering in dilute copper ferrites affects their structural properties. It is concluded that the frustration of magnetic coupling leads to suppression of the cooperative Jahn-Teller effect in dilute copper ferrites with a frustrated magnetic structure.

In this work, magnetic and structural properties of single-phase Tb0.3Dy0.67Ho0.03Fe2−xCox (0≤x≤1.6) alloys have been investigated using X-ray diffraction, 57Fe Mössbauer spectroscopy, Vibrating Sample Magnetometer and standard strain gauge techniques. The lattice parameter a and saturation magnetization decrease with increasing Co content. The composition dependence of Curie temperature of Tb0.3Dy0.67Ho0.03Fe2−xCox exhibits a wide maximum at 0.4≤x≤1.0. The magnetostriction of the alloys under study was examined in applied magnetic field up to 10kOe. The experimental results indicated that compounds with high Co content show superior magnetostrictive properties in low magnetic fields (H≤2kOe).

An attempt is made to reveal the self-organization of atomic magnetic moments in rare-earth ferrimagnets of the TbFe2 type, an effect reported on in the works of S.K. Godovikov. A careful experimental study and a critical analysis of the data reported in his publications suggest that there are no grounds to maintain that this phenomenon exists.

The investigation of magnetic properties of diluted ferrite NiGa0.7Al0.7Fe0.6O4 is carried out. The anomalous behaviour of spontaneous magnetization σs(T), coercive force Hc(T) and derivative of spontaneous magnetization (dσs/dT)(T) is revealed for the sample with frustrated magnetic structure. It is found that the Mossbauer spectrum is doublet at the temperature T = 295 K of the investigated ferrite. This is proved that the magnetic structure represents clusters formed by short-range magnetic order at the temperature below the Curie temperature TC. © MISM2005. All rights reserved

The radioactive decay curve of the 125mTe nucleus is measured in the environment of stable 125Te nuclei representing a Mössbauer resonant screen. Thorough analysis shows that the decay of the 125mTe nucleus corresponds to the standard exponential law with half-life T1/2≈58 days without oscillations.