The magnetic and magnetocaloric characteristics of the Mn1.9Cu0.1Sb alloy were studied. The presence of a relatively sharp decrease in the magnetization in the region of 100 K is established, which, according to ab initio calculations, can be interpreted as antiferromagnetism–ferrimagnetism transitions. The presence of a magnetic phase transition from a ferrimagnetic to an antiferromagnetic state (F ↔ AF) leads to the appearance of an inverse magnetocaloric effect, which is preserved in magnetic fields up to 10 T.

Investigations into the influence of the substrate type (a glass substrate with a molybdenum sublayer, tantalum and molybdenum foils) on the surface morphology of Cu2ZnSnSe4 thin films obtained by selenization of electrochemically deposited and preliminary annealed metallic precursors are presented. Metal foils are attractive for use as substrates of solar cells in both ground and space objects due to their light weight, flexibility, and the possibility of using the commercial roll-to-roll technology of film fabrication, leading to a reduction in the cost. At different stages of Cu2ZnSnSe4 film preparation, their surface morphology is studied by atomic-force microscopy and scanning electron microscopy in combination with energy-dispersive spectrometry. The metal substrate morphology is demonstrated to have an insignificant effect on the surface morphology of Cu2ZnSnSe4 films, indicating that flexible-foil substrates are promising for the production of thin-film solar cells.

The magnetic and structural characteristics of the solid solutions MnNi1–x Fe x Ge (0.10 ≤ x ≤ 0.25) have been investigated. At T = 290 K, the solid solutions have a hexagonal structure of the Ni2In type. The magnetic properties of MnNi1–x Fe x Ge (0.10 ≤ x ≤ 0.25) weakly depend on the type of heat treatment. Based on the magnetometric and Mössbauer data, it has been found that, in the solid solutions MnNi1–x Fe x Ge (0.10 ≤ x ≤ 0.25) with iron concentrations x = 0.10–0.15, the iron atoms are statistically distributed over the octahedral and trigonal-bipyramidal positions. At concentrations above xx = 0.15, iron atoms replace only the manganese atoms in the octahedral positions, whereas nickel atoms in the trigonal-bipyramidal positions are not replaced by the iron atoms.

The Mössbauer spectroscopy on iron, antimony, and tin isotopes was applied to study the hyperfine magnetic interactions in the iron antimonide Fe1.22Sb of a B8-type crystal structure. The values of effective magnetic fields in the temperature range 10–150 K were calculated for the iron atoms at structurally nonequivalent positions. It was shown that antimony in Fe1.22Sb is not involved into magnetic interactions at T = 77 K in contrast to tin introduced into the compound as a Mössbauer probe.

Получены твердые растворы составов Mn1.1Sb1yAly (01.1Sb1ySiy (0В8. Атомы алюминия и кремния замещают сурьму в анионной подрешетке антимонида марганца. Магнитные измерения показали, что замещения в пределах фазы В8 практически не влияют на удельную намагниченность и температуру Кюри. Результаты мессбауэровских исследований подтвердили анионный характер замещений.

Mn1.5 − x Cu x Sb (x ≤ 0.30) and Mn1.5 − x Zn x Sb (x ≤ 0.10) solid solutions have been prepared using high-pressure high-temperature processing, and their structural and magnetic properties have been studied. The results of magnetic and Mössbauer measurements indicate that the interatomic magnetic interactions in the solid solutions are markedly weaker compared to those prepared by direct melting of elemental mixtures.

Solid solutions in the (Mn1 − x Fe x )1.68Sn system (x ≤ 0.5) with a Ni2In-type structure are synthesized by the solid-phase reaction method in a stepwise temperature regime. The unit cell parameters a and c decrease with an increase in the iron concentration in the alloys and become equal to a = 0.430 nm and c = 0.538 nm for the (Mn0.5Fe0.5)1.68Sn alloy. A superstructure with the unit cell parameters a ss = 3a and c ss = c is revealed in alloys of the system under investigation. The specific magnetization of the alloys increases nonlinearly from 53 G cm3 g−1 in the Mn1.68Sn alloy to 72 G cm3 g−1 in the (Mn0.5Fe0.5)1.68Sn solid solution. The Curie temperature changes from 270 K in the initial alloy of the composition Mn1.68Sn to 365 K in the alloy of the composition (Mn0.5Fe0.5)1.68Sn. All solid solutions in the (Mn1 − x Fe x )1.68Sn (x ≤ 0.5) system exhibit metallic conductivity in the temperature range from 77 to 450 K.

Solid solutions in the (Mn1 - x Fe (x) )(1.68)Sn system (x a parts per thousand currency sign 0.5) with a Ni2In-type structure are synthesized by the solid-phase reaction method in a stepwise temperature regime. The unit cell parameters a and c decrease with an increase in the iron concentration in the alloys and become equal to a = 0.430 nm and c = 0.538 nm for the (Mn0.5Fe0.5)(1.68)Sn alloy. A superstructure with the unit cell parameters a (ss) = 3a and c (ss) = c is revealed in alloys of the system under investigation. The specific magnetization of the alloys increases nonlinearly from 53 G cm(3) g(-1) in the Mn1.68Sn alloy to 72 G cm(3) g(-1) in the (Mn0.5Fe0.5)(1.68)Sn solid solution. The Curie temperature changes from 270 K in the initial alloy of the composition Mn1.68Sn to 365 K in the alloy of the composition (Mn0.5Fe0.5)(1.68)Sn. All solid solutions in the (Mn1 - x Fe (x) )(1.68)Sn (x a parts per thousand currency sign 0.5) system exhibit metallic conductivity in the temperature range from 77 to 450 K.

The features of the magnetic interactions in manganese stannide Mn1.66Fe0.02Sn with a structure of the B82 type are investigated on the basis of Mössbauer-effect measurements on the iron and tin atoms. The Curie temperature of this compound according to the Fe57 data is TC=265K, while for Sn119 it is TC=250K; both of these are higher than the value of TC determined by the Faraday method (240K). The participation of the tin atoms in the magnetic exchange interaction in MnII–Sn–MnII chains is confirmed. It is shown that effectively only three of the five manganese atoms occupying the trigonal–bipyramidal MnII positions nearest to a tin atom have any influence on the magnetic interactions at the tin nucleus. The magnetic fields at the nuclei of the manganese atoms in the trigonal–bipyramidal positions in MnII–Sn–MnII chains are significantly (2–2.5 times) larger than the field at the nuclei of the manganese atoms in the octahedral positions in MnI–MnI.

Fluorine-and cerium-substituted thallium-based high-temperature 2212 superconductors are synthesized, the limits of solubility of the substitutes are investigated, the critical temperatures of the superconducting transitions are measured, and the local structure is refined using the Mössbauer technique.

High-Tc superconducting ceramics with the compositions Tl2Ba2CaCu2O8 − x/2 (0 ≤ x ≤ 0.3), Tl2Ba2(Ca1 − yCey)Cu2Ox (0 ≤ y ≤ 0.2), and Tl2Ba2(Ca0.9Ce0.1)(Cu1.98Fe0.02)F0.2O8.01 are synthesized. Partial fluorine substitution for oxygen in Tl2Ba2CaCu2O8 − x/2 (0 ≤ x ≤ 0.1) alters the carrier density in the Cu-O planes of the material, raising its superconducting transition temperature from 106 to 110 K. Partial cerium substitution for calcium in Tl2Ba2(Ca1 − yCey)Cu2Ox (0 ≤ y ≤ 0.2) reduces Tc. The combined substitution in Tl2Ba2(Ca0.9Ce0.1)(Cu1.98Fe0.02)F0.2O8.01 has an insignificant effect on Tc.

PbTeSnSe and GeSnTe compound semiconductors were studied by 119 Sn Mössbauer spectroscopy in the temperature range from 5 to 240 K. Analysis of temperature dependences of the quadrupole splitting of Mössbauer spectra measured during a cooling-heating cycle confirmed the presence of off-center atoms in these materials.

The features of formation of needle-shaped Fe and FeCu particles in pores of anodic aluminum oxide and the effect of composition and crystal and magnetic structure of the particles on the properties of the resulting magnetic heterostructures were studied.

A direct experimental proof of the adequateness of the unharmonically unstable oxygen atom's sublattice model for the YBa2Cu3-xFexO7-delta-base high temperature superconductor is received on the basis of the temperature dependence of the quadrupole splitting of Fe-57 Mossbauer spectra. (C) 1998 Elsevier Science B.V. All rights reserved.

Quadrupole splitting and effective characteristic temperatures of Sn-119 in Ni(Sb,Sn) and Co(Sb,Sn) solid solutions with B8-type structure have been studied by Mossbauer Effect method. The electric field gradient at metalloid atoms was estimated in point charge model for different variants of local environment.On the basis of the comparison between experimental Quadrupole Splitting values and estimated Electric Field Gradient ones it was concluded that MeII-Sn pairs occur more often than MeII-Sb when the amount of transition metal in ditrigonal-dibipyramidal positions is less than 0.10.

Direct experimental proof of adequacy of the unharmonically unstable oxygen atom's sublattice model in the YBa2CU3-xFexO7-delta base high temperature superconductor was received on the bases of temperature dependence of Quadrupole Splitting of Mossbauer spectra.