F.G. Vagizov

Magnetic properties and 57Fe Mössbauer effect investigation in U1−xYxFe10Si2 solid solutions

Abstract The solid solutions U1−xYxFe10Si2 have been studied by means of X-ray diffraction, 57Fe Mossbauer effect and magnetic investigations. In the intermediate concentration range, a redistribution of the iron and silicon atoms over non-equivalent positions was observed despite the fact that both ternaries have similar occupancies in all positions. Such a redistribution could be a reason for the slight non-linearity observed in the concentration dependences of lattice parameters and magnetic properties. The results of a hyperfine field study were used to estimate the uranium magnetic moment in UFe0Si2, which is about 0.5μB and coupled ferromagnetically with the iron sublattice magnetic moment.

57Fe Mössbauer effect in UFexAl12−x system

Abstract 57 Fe Mossbauer effect examinations were carried out on UFe x Al 12− x alloys with x = 4, 5 and 6 in the temperature range 14–370 K. The spectra for x =5 and 6 can be fitted with the Fe atoms distributed over the 8( f ), 8( j ) and 8( i ) positions, whereas for x =4 the Fe atoms are located at the 8( f ) sites only, in agreement with earlier results. The hyperfine fields corresponding to the three sites ( f, j, i ) are 54%, 43% and 3% for x =5 and 58%, 35% and 7% for x =6 respectively. The Curie points determined from H hf ( T ) plots are 162, 265 and 350 K for x =4, 5 and 6 respectively, in fair agreement with the results of magnetic examinations.

Magnetic properties and Mössbauer effect studies of Ce1−xScxFe4 Al8 system

The investigations of the magnetic and electrical properties as well as the 57Fe Mossbauer effect are presented for Ce1−xScxFe4Al8 solid solution with 0<x<1 in the temperature range 4–300 K. Magnetic susceptibility follows a Curie–Weiss law above 200 K. The effective magnetic moment decreases with the Sc content. At temperatures lower than 130 K all compounds studied are antiferromagnets. The Neel temperature, TN is not affected by substitution of Sc for Ce. TN has no reflection in any anomaly in ρ(T). The Mossbauer spectra at temperatures lower than TN exhibit one Zeeman sextet related to the Fe nucleus at the 8(f) position. The hyperfine parameters Hhf, IS, QS have been estimated as a function of Sc concentration. The increasing of Sc content diminishes Hhf on the Fe nucleus. The calculations of electron-density distribution along the 111 direction in elemental crystallographic cell indicate a remarkable increase of electron charge at the Fe sites with the Sc content increasing. The 40–49° cone angles of the Fe sublattices at 12 K have been estimated from Mossbauer spectra analysis.

57Fe Mössbauer effect study of the UFe10−xAlxSi2 system

Abstract 57 Fe Mossbauer spectroscopy has been used to study the UFe 10− x Al x Si 2 system in the temperature range 14–295 K for x ≤ 3.0 (single-phase region). The Mossbauer spectra provide values of the hyperfine fields and their deconvolution gives information about the occupancy of the individual crystallographic positions 8f, 8j and 8i by the Fe atoms. The data obtained explain the change in the anisotropy character for x = 2 and provide evidence for the U sublattice contribution to the magnetic ordering. The results obtained are discussed in comparison with earlier magnetic measurements in terms of geometrical factors.

Magnetic, transport and Mössbauer effect study of UFeAl

We present the results of magnetic susceptibility, electrical resistivity and Mossbauer effect measurements performed on two crystallographic structures of UFeAl: high-temperature (HT) and low-temperature (LT) phases, i.e. MgZn2 and Fe2P-type structures respectively. The exchange-enhanced Pauli susceptibility and spin-fluctuation characteristics of the temperature dependence of the electrical resistivity of UFeAl are almost independent of the type of crystal structure. 57Fe Mossbauer spectra of both crystallographic phases of UFeAl, recorded in the temperature range 10–295 K, consist of two symmetric quadrupole doublets for each crystal structure associated with the non-equivalent crystallographic positions of Fe. The Debye temperatures for the HT and LT structures of UFeAl were also estimated.

Magnetic properties and 57Fe Mössbauer effect in the substoichiometric Ln Fe (Re,Mo) systems with the ThMn12 structure

Abstract Magnetic properties and 57 Fe Mossbauer effect have been investigated in the following compounds: Ce 1.33 Fe 8.8 Mo 3.2 , Ce 1.33 Fe 10 Re 2 , Pr 1.64 Fe 7.2 Re 4.8 and Sm 1.8 Fe 7.5 Re 4.5 in the broad temperature range. All these compounds turned out to be ferromagnetic at low temperature; however, under an applied magnetic field of 5 T, saturation is not reached. The Curie points and saturation magnetic moments determined in both experiments are in fair agreement with previous results obtained on stoichiometric samples, except for the Pr compound. In all samples, an admixture of other phases was detected. The XRD patterns, however, do not give indication of their structure.

Magnetic properties and 57Fe Mössbauer effect in UFe10−xNixSi2 alloys

The magnetic properties and 57Fe Mossbauer effect in the UFe10−xNixSi2 system were investigated over a broad temperature range. Magnetic measurements revealed a ferromagnetic character, with two anomalies in the temperature dependence of the susceptibility for x > 6 but only one anomaly for x < 6. The temperature of the last anomaly increases as x decreases. The high-temperature anomaly seems to be related to the precipitation of free nickel. The field dependence of the magnetization exhibits remanence for x ⩾ 4. The 57Fe Mossbauer effect demonstrates that only iron contributes to the magnetic ordering observed at lower temperatures. It is shown that the substitution of Ni for Fe results in a strong preferential occupation by Ni of the 8(f) site. The decrease in the Curie point and the saturation magnetization is attributed to the decrease in the number of the nearest neighbour Fe atoms.

Sublattice contributions to the magnetism of UFe10Si2

Abstract Solid solutions based on UFe 10 Si 2 (U-Y, Fe-Co, Fe-Al, Si-Mo substitutions) were studied to determined the contributions from the U and Fe sublattices to the total magnetic properties. U has a magnetic moment of about 0.5 μ B ordered ferromagnetically with Fe and enhances uniaxial magnetic anisotropy of the compound.

Magnetic properties and 57Fe Mössbauer effect of uranium pseudoternaries with the ThMn12-type structure

Abstract The magnetic properties and the 57 Fe Mossbauer effect (ME) of UFe 9.9 Cr 0.1 Si 2 and UFe 10 Si 1.9 Sn 0.1 have been investigated in a broad temperature range and under magnetic fields up to 14 T in the case of the magnetization measurements. Both compounds exhibit ferromagnetic properties below about 650 K. The saturation magnetizations amount to about 15.9μ B /f.u. (magnetization) and about 15.7μ B /f.u. (ME) for the first compound, and to about 18.2μ B /f.u. (magnetization) and about 15.9μ B /f.u. (ME) for the second. These values suggest that the uranium atom contributes to the magnetism of these materials.

Structure, magnetic properties and the 57Fe Mössbauer effect in the LuFe11−xAlxTi system

Abstract The structure, magnetic properties and the 57Fe Mossbauer effect of LuFe11−x,AlxTi alloys were investigated in the temperature range of 4.2–500 K. The system exists as a single phase for the x