The effect of substitutional 4f-elements on the magnetism of rare-earth compounds RFe2-type with the Laves phase structure is studied to find new multifunctional materials, as well as to define the macro- and microscopic parameters of multicomponent magnets. The crystal structure of (Er,Y,Sm)Fe2 compounds is investigated by X-ray powder diffraction. Detailed information on the magnetic properties of the iron sublattice for multicomponent compounds with three different rare-earth elements is obtained for the first time by means of the 57Fe Mössbauer spectroscopy. The main regularities in the magnitude variation of magnetocaloric effect and magnetostriction (linear, anisotropic and volume) in varying composition of the (Er,Y,Sm)Fe2 compounds are determined.

New (Er1 – xYx)0.8Sm0.2Fe2 multicomponent alloys with a substitution parameter of x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0 are synthesized and their atomic crystal structure and magnetic properties are studied. It is shown that full magnetic compensation can be expected in the region of 0.2 < xcomp < 0.4. Er0.8Sm0.2Fe2 alloy exhibits temperature-dependent magnetization compensation at Tcomp = 400 K.

The paper presents the results of the synthesis, structural studies, and investigation of the magnetic and magnetostriction properties of new multicomponent alloys based on heavy rare-earth metals ( R _1-x Y x ) 0.8 Sm 0.2 Fe 2 , where R = Tb, Gd, Dy, and Er, х = 0, 0.2, 0.4, 0.6, 0.8, and 1. It was found that alloys of these systems (except for the system with Tb) are single-phase and have the cubic С 15 Laves structure. The lattice parameters for all systems were shown to change linearly with increasing х . The main magnetic characteristics of the alloys were determined. The following practically important phenomena were found: the magnetic compensation of the sublattice magnetization, the spin reorientation, and the sign inversion of magnetostriction constants.

В работе представлены результаты синтеза и исследования новой многокомпонентной системы (Dy1-xYx)0.8Sm0.2Fe2, в которой магнитоактивные атомы диспрозия замещены атомами слабомагнитного самария, а затем немагнитного аналога РЗМ – иттрия. Параметр замещения принимает значения x = 0, 0.2, 0.4, 0.6, 0.8, 1.0. Установлено, что структура сплавов соответствует кубической структуре фазы Лавеса С15. Все сплавы являются однофазными, содержание примесной фазы не превышает 5%. Установлены параметры структуры и основные магнитные характеристики сплавов, а также их зависимость от параметра замещения x. Показано, что спин-переориентационные переходы, присущие соединению SmFe2, сохраняются в каждом из сплавов системы. В то же время в сплаве с x = 0,8 наблюдаются аномалии теплового расширения инварного типа.

Multicomponent alloys based on light and heavy rare-earth metals of the compositions R (Fe _1-x Al x ) 2 ( R = Pr, Nd, Tb) and Y(Fe _1-x Al x ) 2 were synthesized and their crystal structures were determined. For all these systems, the lattice parameter a of the cubic C 15 Laves phase was shown to linearly vary with increasing substitution parameter x . It was found that alloys of these systems undergo complex structural transformations caused by a change in the Al concentration in the samples.

We consider the features of the behavior of thermal expansion and magnetostriction in magnetically ordered substitutive alloys based on heavy rare earth metals, namely: TbFe2, Tb0.8Zr0.2Fe2, Tb0.8Sm0.2Fe2 and Gd0.8Sm0.2Fe2. It is found that the of thermal expansion anomalies observed in alloys are mainly due to the competition of exchange interactions. In TbFe2 and Tb0.8Zr0.2Fe2 alloys invar-type features are observed in a wide temperature range.

The paper presents the results of the synthesis, structural studies, and investigation of the magnetic and magnetostriction properties of new multicomponent alloys based on heavy rare-earth metals (R1-xYx)(0.8)Sm0.2Fe2, where R = Tb, Gd, Dy, and Er, x = 0, 0.2, 0.4, 0.6, 0.8, and 1. It was found that alloys of these systems (except for the system with Tb) are single-phase and have the cubic.15 Laves structure. The lattice parameters for all systems were shown to change linearly with increasing.. The main magnetic characteristics of the alloys were determined. The following practically important phenomena were found: the magnetic compensation of the sublattice magnetization, the spin reorientation, and the sign inversion of magnetostriction constants.

The paper presents the results of the synthesis, structural studies, and investigation of the magnetic and magnetostriction properties of new multicomponent alloys based on heavy rare-earth metals (R1-xYx)0.8Sm0.2Fe2, where R = Tb, Gd, Dy, and Er, х = 0, 0.2, 0.4, 0.6, 0.8, and 1. It was found that alloys of these systems (except for the system with Tb) are single-phase and have the cubic С15 Laves structure. The lattice parameters for all systems were shown to change linearly with increasing х. The main magnetic characteristics of the alloys were determined. The following practically important phenomena were found: the magnetic compensation of the sublattice magnetization, the spin reorientation, and the sign inversion of magnetostriction constants.

A study is performed of the behavior of thermal expansion and magnetostriction in magnetically ordered substitution alloys based on heavy rare-earth metals: TbFe 2 , Tb 0.8 Zr 0.2 Fe 2 , Tb 0.8 Sm 0.2 Fe 2 , and Gd 0.8 Sm 0.2 Fe 2 . It is found that anomalies of thermal expansion observed in the alloys are mainly due to competition between exchange interactions. Invar-type features are observed in TbFe 2 and Tb 0.8 Zr 0.2 Fe 2 alloys in a wide range of temperatures.

A study is performed of the behavior of thermal expansion and magnetostriction in magnetically ordered substitution alloys based on heavy rare-earth metals: TbFe2, Tb0.8Zr0.2Fe2, Tb0.8Sm0.2Fe2, and Gd0.8Sm0.2Fe2. It is found that anomalies of thermal expansion observed in the alloys are mainly due to competition between exchange interactions. Invar-type features are observed in TbFe2 and Tb0.8Zr0.2Fe2 alloys in a wide range of temperatures.

В работе приводятся результаты прогнозирования и теоретического моделирования магнитных свойств сплавов многокомпонентных систем на основе тяжелых редкоземельных элементов (R1-xYx)0.8Sm0.2Fe2, где R = Gd, Dy, Ho и Er. Показано, что сплавы с подобным замещением в редкоземельной подрешетке обладают рядом уникальных свойств в определенных концентрационных областях, обусловленные конкурирующими обменными взаимодействиями, как межрешеточными, так и внутриподрешеточными. Для каждой из представленных систем, (Gd1-хYх)0.8Sm0.2Fe2, (Dy1-хYх)0.8Sm0.2Fe2, (Ho1-хYх)0.8Sm0.2Fe2 и (Er1-хYх)0.8Sm0.2Fe2, в модели трехподрешеточного ферримагнетика определены концентрации иттрия, в области которой наблюдается взаимная магнитная компенсация редкоземельной и 3d-подрешеток. На основе экспериментальных результатов, полученных ранее авторами данной работы для аналогичной системы (Tb1-хYх)0.8Sm0.2Fe2, спрогнозировано наблюдение в представленных системах целого ряда уникальных магнитных явлений по мере изменения параметра замещения х.

The paper presents the results of studying the alloy magnetization of the multicomponent system (Tb 1−x Y x ) 0.8 Sm 0.2 Fe 2 . The substitution parameter in this system takes the following values: x = 0, 0.2, 0.4, 0.6, 0.8, 1. In the system, the atoms of magnetic terbium were replaced by atoms of weakly magnetic samarium and nonmagnetic yttrium. X-ray diffraction analysis determined the structure and lattice constant for all compositions. Phase analysis was carried out. It is known that by varying the concentration of components, temperature, and external fields, one can successfully influence the magnitude of exchange interactions leading to one or another type of magnetic ordering in the rare-earth intermetallic metals. Therefore, the main goal in this work was to investigate the possibility of observing the magnetic phase transition – ferrimagnetism – ferromagnetism - in the alloys of the system from the curves of the field dependence of magnetization in strong fields up to 60 T. The studies were carried out at the liquid helium boiling point. The main magnetic characteristics of the alloys of this system were determined, such as saturation magnetization σ s , magnetic moment per formula unit μ and magnetic moment μ Fe on iron atoms. Their dependences on the concentration of yttrium were established. The possible values of the magnetic moment per formula unit in the case of ferromagnetic ordering of these alloys were calculated theoretically. It was concluded that these fields are insufficient to observe the ferrimagnetism – ferromagnetism phase transition.

The paper presents the results of studying the Mossbauer effect on alloys of the multicomponent system (Tb 1-X Y X ) 0.8 Sm 0.2 Fe 2 (substitution parameter X = 0, 0.2, 0.4, 0.6, 0.8, 1). This system is based on the TbFe 2 compound, which has a cubic crystal structure and the highest magnetostriction constants among rare-earth intermetallic compounds of the RFe 2 type. Substitution of atoms magnetic terbium for weakly magnetic samarium (20%) and nonmagnetic yttrium leads to exchange interactions altering in the system which should affect the magnitude of hyperfine interactions on 57 Fe nuclei in alloys of this system. The studies were carried out at room temperature. All parameters of the Mossbauer spectrum being isotropic and anisotropic hyperfine fields, quadrupole shift of the components of the spectrum hyperfine structure, and isomeric shift of the Mossbauer line have been determined. Their dependences on the concentration of yttrium have been established.

В работе приводятся результаты исследования температурной зависимости ас-восприимчивости сплавов многокомпонентной системы (Tb1-хYх)0.8Sm0.2Fe2 в области температуры Кюри. Параметр замещения в системе принимает значения х = 0, 0.2, 0.4, 0.6, 0.8, 1. В системе произведено замещение атомов магнитного тербия атома слабомагнитного самария и немагнитным иттрием. Известно, что варьируя концентрацию, компонент, температуру и внешние поля, можно успешно влиять на конкурирующие обменные взаимодействия, приводящие к уникальным явлениям в области фазовых превращений. Поэтому основной целью в данной работе было определение температуры магнитного фазового перехода сплавов системы по кривым температурной зависимости восприимчивости в области температуры Кюри. Показано, что температуры Кюри сплавов данной системы лежат в области высоких температур.

The paper presents the results of the study of magnetic and magnetostrictive properties of rare-earth intermetallides based on TbFe 2 compound: Tb 1-x Zr x Fe 2 , Tb 1–x Sm x Fe 2 and (Tb 1–x Y x ) 0 . 8 Sm 0 . 2 Fe 2 . These alloys have a cubic crystal structure of the Laves phase C15 throughout the substitution region. For the system of alloys Tb 1–x Zr x Fe 2 the single-phase area is limited to the replacement parameter 0 < x < 0.2 and 0.8 < x < 1.0. The compounds of the Tb 1–x Sm x Fe 2 system were studied via X-ray dilatometry. The magnetostriction of alloys within the Tb 1–x Zr x Fe 2 and (Tb 1–x Y x ) 0 . 8 Sm 0 . 2 Fe 2 systems was studied in the temperature range of 80-320 K in magnetic fields of up to 17 kOe via a strain-gauge method. It was found that each system has the phenomenon of sign inversion of magnetostriction constants: in the system Tb 1–x Zr x Fe 2 in the area of replacement parameter x = 0.8, in Tb 1–x Sm x Fe 2 - in the area x = 0.45, and in the system of alloys (Tb 1–x Y x ) 08 Sm 02 Fe 2 at x = 0.6. It was demonstrated that magnetic compensation and spin reorientation phenomena occur in these systems. The obtained results are discussed in the model of alloys with competing exchange interactions.

— This paper presents results on the synthesis of multicomponent Sm 0 . 2 ( Y , Tb ) 0 . 8 Fe 2 alloys and the study of their magnetostriction properties. In this system, it is possible to control competing exchange interactions by varying the concentrations of components, the temperature, and the external magnetic fi eld and to observe a variety of unique phenomena, such as magnetization and magnetostriction compensation. Using X-ray di ff raction analysis, it has been established that these alloys have a cubic crystal structure of the C15 Laves phase. Longitudinal and transversal magnetostrictions were studied within a temperature range from 80 to 300 K in magnetic fi elds of up to 12 kOe. The bulk and anisotropic magnetostrictions were calculated from experimental values. The sign inversion of bulk magnetostriction in Sm 0 . 2 Y 0 . 8 Fe 2 was revealed at T = 150 K. It has been shown that the bulk magnetostriction of some studied alloys is almost invariable and close to zero within a broad temperature range of 150 – 300 K. The results are discussed within the model of a three-sublattice magnet with competing exchange interactions

A comprehensive study of the structure, phase composition, features of the surface topology, the magnetostrictive and thermal properties of the Tb0.8Sm0.2Fe2 compound are performed. The structural features were established at micro- and nanoscale levels, and information on the magnetic domains structure at room temperature was obtained. The results of x-ray diffraction studies in a wide temperature range of 90–760 K, including Curie temperature, are represented. Experimental data on thermal expansion and magnetostriction in magnetic fields up to 12 kOe were obtained and analyzed. Anomalies were found in the thermal expansion curves dl/l (T) and magnetostriction λ (T) at low temperatures. It is established that in compound under study the value of the magnetostrictive effect remains almost unchanged in a wide temperature range 100–300 K in fields up to 3.5 kOe.

The paper presents the results of study of structural and magnetic properties of alloys of quasi-binary systems R(Fe1xMx)2, where R is REE and M is 3d-metal. It is shown that synthesis under extreme conditions, i.e. high temperatures and high pressures makes it possible to obtain alloys with the Laves phase structure, which cannot be obtained under normal synthesis. These are alloys with rare earth elements Yb, Nd and Pr. For all systems studied the structural and magnetic phase diagrams are determined. The areas of single-phase patterns are determined. It is shown that structural phase transitions occur through the morphotropic region, where two Laves phases coexist, i.e. cubic C15 and hexagonal C14 phases. In addition the temperatures of magnetic order-disorder phase transitions (Curie temperatures) are determined for these systems. For the system of alloys Pr(Fe1xAlx)2 these values are compared with the data obtained from Mossbauer studies of temperature.

A complex study of the structure, phase composition, features of the surface topology, magnetostriction and thermal properties of the compound Tb 0.8 Sm 0.2 Fe 2 was carried out. Peculiarities of the structure at the micro- and nanolevel were found; information on the magnetic domain structure at room temperature was obtained. X-ray structural studies in a wide temperature range from 90 to 760 K, including the Curie point, are presented. Experimental data on the thermal expansion and magnetostriction in magnetic fields up to 12 kOe were obtained and analyzed. Anomalies on the thermal expansion curve Δ l / l ( T ) and on the magnetostriction dependence λ( T ) in the low-temperature region were revealed. The magnetostriction effect in the studied compound was found to be almost constant in a wide temperature range of 100–300 K and in fields up to 3.5 kOe.