The X-ray Rietveld method has been used to refine the structure, determine the lattice periods, and study the phase composition of the samples of multicomponent polycrystalline solid solutions TbCo _(2-x) Inx (х = 0, 0.05, 0.1, 0.15, 0.20, 0.25, 0.3, 0.35, 0.4), which are characterized by large values of magnetostriction saturation. With an increase in the indium concentration, the content of the TbCo2 phase with a Laves phase structure decreases, the content of the TbCo3 phase increases, and a Tb11Co4In9 phase is formed. The lattice period in the TbCo2 compound (sp. gr. Fd 3̅ m) changes nonlinearly: increases in the range of x = 0–0.1 from a = 7.209(8) Å to a = 7.216(1) Å due to the replacement of cobalt atoms with indium atoms, having a larger radius. Then, in the concentration range of x = 0.15–0.4, it decreases to a = 7.205(1) Å at х = 0.4 due to the replacement of terbium atoms with indium and formation of structural defects.

Abstract—Multicomponent polycrystalline TbInxCo2 – x (with х = 0–0.2) solid solutions are prepared for the first time, and their crystal structure and magnetic, magnetocaloric, and magnetostrictive properties are studied. X-ray diffraction patterns taken at room temperature demonstrate mainly the presence of the cubic C15 Laves phase in all samples. As the indium content increases to x = 0.1, the lattice parameter is found to increase; the further increase in the indium content to х = 0.2 leads to a decrease in the lattice parameter. In this case, the Curie temperature TC monotonically increases to 245 K. The isotheral magnetic entropy change ΔSmag is calculated in accordance with magnetic measurements using the thermodynamic Maxwell’s relation. At a magnetic field change from 0 to 1.8 T, the maximum entropy change monotonically decreases and, for composition with x = 0.2, is 1.8 J/(kg К). As the indium content increases to x = 0.05, the volume magnetostriction increases. The further increase in the indium concentration leads to the decrease in the peak values and their shift to high temperatures.

Polycrystalline TbxDy1-xR0.1Fe2-zCoz (R = Nd, Pr, x = 0.2, 0.3; z = 0, 1.3) cubic Laves phase alloys with MgCu2-type structure were prepared by arc melting followed by homogenizing annealing. The crystal structure, magnetic properties, and magnetostriction have been investigated. Compounds with high values of magnetostrictive susceptibility were found in the temperature range 150-300 K. Compounds with partial substitution of cobalt for iron demonstrate a change in the sign of anisotropic magnetostriction. This work continues the search for magnetostrictive materials with inexpensive neodymium and praseodymium.

In the recent years, a number of pseudo-binary RT2 Laves phases with morphotropic phase transitions, i.e., systems of compounds having a morphotropic phase boundary in the phase diagram, have attracted special attention in the process of searching for compounds with high or, on the contrary, almost zero magnetostriction values. In this work, we study the magnetic and magnetostrictive properties of multicomponent systems based on compounds Tb0.2Dy0.8 – xGdxCo2 and Tb0.2Dy0.8 – xGdxCo1.9Al0.1, in which a morphotropic phase transition is observed when dysprosium is replaced by gadolinium. A relationship between the temperature behavior, the sign and magnitude of magnetostrictive deformations, and the type of cubic lattice distortion of the studied Laves phases is revealed. In the region of magnetic phase transitions, the magnetocaloric effect is investigated.

The rare earth SmFe2 and CeFe2 Laves phases and solutions on base of them with partial substitution by terbium ((Sm,Tb)Fe-2, (Ce,Tb)Fe-2) were obtained. The lattice parameters of compounds were refined by Rietveld method. To study the effect of substitution on the magnitudes of magnetostriction and magnetization of alloys, measurements in the temperature range 78-360 K in magnetic fields up to 1.2 T were carried out. Using BelovArrot method, the Curie temperatures for series of compounds in Ce1-xTbxFe2 (x = 0; 0.1 and 0.2) system were determined. It was found that in the Sm1-xTbxFe2 system, a change in the sign of magnetostriction should be observed at x = 0.4 - 0.45, which correlates well with X-ray diffraction data.

Оver recent years in the process of searching for compounds with high or almost zero magnetostriction values, a number of pseudo-binary Laves RT2 phases with morphotropic phase transitions are attracted particular attention. That is, systems of compounds with a morphotropic phase boundary in the phase diagram. In this paper, the magnetic and magnetostrictive properties of multicomponent systems of compounds Tb0.2Dy0.8-хGdxCo2 and Tb0.2Dy0.8-хGdxCo1.9Al0.1 in which a morphotropic phase transition is observed when replacing dysprosium with gadolinium have been studied. A relationship between the temperature behavior, the sign and magnitude of magnetostrictive deformations, and the type of distortion of the cubic lattice of the studied Laves phases is revealed. In the region of magnetic phase transitions, the magnetocaloric effect was investigated.

In this study, the SmFe2 alloy in a high-purity single-phase state has been prepared by the induction melting technique. The surface features of the alloy at room temperature were investigated using the atomic-force and magnetic-force microscopy. The forming of heterogeneous granular structure was revealed, the main structural elements were determined. The presence of the complex domain structure was shown, its description was presented and the domain sizes were found. The results of X-ray structural studies over the temperature range from 100 to 300 K were presented. The experimental data on the temperature dependences of magnetostriction in magnetic fields up to 1.2 T were obtained and analyzed in the region of the spin-reorientational phase transition. The existence of the "angular" phase was indirectly confirmed, its temperature boundaries were refined.