Magnetic and Mössbauer measurements were performed for Mn1-xFexNiGe solid solutions. The Mössbauer data obtained suggest that the iron atoms at small concentrations x < 0.20 prefer to fill trigonal ...bipyramidal positions substituting the nickel atoms and thus do not participate in magnetic interactions. This is consistent with a decrease of magnetization in the x < 0.20 samples, evident from the magnetic measurements data. As the concentration increases above x > 0.20 in Mn1-xFexNiGe, the iron atoms replace both the nickel atoms in trigonal bipyramidal and the manganese atoms in octahedral positions.
•Magnetic and Mössbauer measurements were performed for Mn1-xFexNiGe solid solutions.•The iron atoms at small concentrations x < 0.20 prefer to fill trigonal bipyramidal positions substituting the nickel atoms.•At x > 0.20, the Fe atoms replaces both the nickel atoms in trigonal bipyramidal and the Mn atoms in octahedral positions.
The analysis of 57Fe Mössbauer spectroscopy results for cation and anion substituted Mn2-xFexP1-yAsy was done in order to find out the influence of the Mn/Fe ratio on the magnetic properties of solid ...solutions and to compare experimental hyperfine parameters with those calculated from firstprinciples.The correlation between third Mössbauer sextet in Mn2-xFexP0.5As0.5 spectrum at 77K and stabilization of the antiferromagnetic phase for x = 0.5-0.6 was found on the basis of comparison between the magnetic phase diagrams and the "hyperfine field - iron content" dependence. The observed qualitative difference for Mn2-xFexP0.5As0.5 and MnFeAsyP1-y "hyperfine field - concentration" diagrams was interpreted on the basis of different mechanisms of magnetic phase stabilization and the different configurations of tetrahedral anionic environment of iron ions for systems with cation and anion substitutions.
The magnetic characteristics of chromium and iron containing MnNiGe-based alloys with several types of quenching and annealing were investigated. It was found that the quenched Mn0.89Cr0.11NiGe has a ...spontaneous and magnetic field induced magnetostructural first-order transitions at room temperature. These transitions might be accompanied by a large magnetocaloric effect. In general, Mn0.89Cr0.11NiGe can be classified as promising material for use in the magnetocaloric application at room temperatures. The first order magnetostructural phase transition from the ferromagnetic to paramagnetic state is not realized in MnNi0.90Fe0.10Ge. In contrast to Mn0.89Cr0.11NiGe, however, the FM state in quenched-on-wheel MnNi0.90Fe0.10Ge is preserved to the lowest temperatures. Based on the set of the magnetic properties, it has been concluded that the iron containing MnNiGe-based alloys are less promising for practical use.
The MnSb(Zn) and MnSb(Cu) solid solutions with NiAs-type of crystal structure have been obtained. The existence regions of mono-phase solutions have been determined. Zn and Cu can substitute 10% ...atomic for Mn. On the basis of magnetic measurements it was supposed that the Cu or Zn atoms preferable occupy the MeII sites of NiAs-structure if the amount of nonmagnetic substitution not exceed 10% atomic. The preferable occupation of MeII sites by nonmagnetic atom manifests in rising of the Curie temperature of solid solutions relatively unsubstituted alloy.
We have prepared Mn1.1Sb1 ? y Al y (0 < y ? 0.2) and Mn1.1Sb1 ? y Si y (0 < y ? 0.1) solid solutions with the B8 structure, in which the aluminum and silicon atoms substitute for antimony in the ...anion sublattice of manganese antimonide. Magnetic measurements have shown that substitutions within the stability region of the B8 phase have little effect on the mass magnetization and Curie temperature of the material. Mossbauer spectroscopy results confirm the anion nature of the substitutions.
Fluorine and cerium substituted Tl-2212 high-Tc superconductors were produced. X-ray diffraction, Mossbauer effect method, temperature measuring of the resistances and a.c. susceptibilities for all ...Tl2Ba2Ca1-yCeyCu1.98Fe0.02O8-x/2Fx (0x0.2 and 0y0.1) were applied. It was found that the cerium admixture does not affect significantly the Tl-2212 superconductor properties. Fluorine admixture alone appreciably affects the value of superconducting transition temperature. The biggest increase in Tc is 10K and is realised for x=0.10-0.20. Substituting admixtures are not clearly exhibited in Mossbauer parameters, i.e. do not influence Fe-O bonding tangibly.
The analysis of 57Fe Mossbauer spectroscopy results for cation and anion substituted Mn sub(2-x)Fe sub(x)P sub(1 -y)As sub(y) was done in order to find out the influence of the Mn/Fe ratio on the ...magnetic properties of solid solutions and to compare experimental hyperfine parameters with those calculated from firstprinciples. The correlation between third Mossbauer sextet in Mn sub(2-x)Fe sub(x)P sub(0 .5)As sub(0.5) spectrum at 77K and stabilization of the antiferromagnetic phase for x = 0.5-0.6 was found on the basis of comparison between the magnetic phase diagrams and the "hyperfine field - iron content" dependence. The observed qualitative difference for Mn sub(2-x)FexP sub(0.5)As sub(0.5) and MnFeAs sub(y)P sub(1-y) "hyperfine field - concentration" diagrams was interpreted on the basis of different mechanisms of magnetic phase stabilization and the different configurations of tetrahedral anionic environment of iron ions for systems with cation and anion substitutions.
(MnZn)1 a x Fe x Sb solid solutions with the Cu2Sb structure have been prepared through heterophase reactions. Their stability range is 0 < x less than or equal to 0.2. The magnetic interaction in ...the solid solutions has a ferromagnetic character. The Curie temperature and mass magnetization of the solid solutions have been determined, and the iron dopant has been shown not to participate in magnetic interaction.
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