Magnetostriction of a non-modulated martensite was measured for Ni2.27Mn0.73Ga ferromagnetic shape memory alloy in steady magnetic fields mu H-0 up to 10 T at temperatures below room temperature and in mu H-0 <= 1 T at temperatures above room temperature. Linearity of the longitudinal magnetostriction lambda(parallel to) observed at high fields mu H-0 > 6 T implies that the magnetostriction is associated with a 3d electron band. The anisotropic magnetostriction obtained in a magnetic field mu H-0 = 1 T at T = 4.2 K is similar to 16 ppm and decreases down to 3 ppm with the increase in temperature. The volume magnetostriction is positive but very small (similar to 0.6 ppm) under these conditions. In the region of the magnetostructural phase transition the longitudinal and volume magnetostriction showed a complex sigh-changing behavior which depends on the strength of applied magnetic field. Thermal expansion coefficient alpha of Ni2.27Mn0.73Ga in the martensitic state was measured to be alpha similar to 13 x 10(-6) K-1 which is comparable with the thermal expansion coefficient of a non-stoichiometric Ni2.19Mn0.81Ga single crystal. (c) 2018 Elsevier B.V. All rights reserved.

Comparative analysis and generalization of the influence of La on the structural and magnetic properties of R1-xLaxNi2 (R = Tb, Dy, Ho) solid solutions is presented. All the studied R1-xLaxNi2 solid solutions solidify with the formation of a Laves-phase superstructure corresponding to the F (4) over bar 3m space group. The magnetic properties are dominated by rare earth interactions and the substitution of R atoms with La significantly modifies the magnetic behaviour of the R1-xLaxNi2 system. Replacing of magnetic R with the nonmagnetic La results in magnetic dilution leading to the weakening of exchange interactions and decrease of the ordering temperature. In the case of Tb1-xLaxNi2 and Dy1-xLaxNi2 the ferromagnetic properties are reduced as the lanthanum content increases to 80% and for Ho1-xLaxNi2 the ferromagnetic ordering is destroyed as the lanthanum content increases to the values above 80%. The magnetic transition in all the studied samples is of second order character. The Debye temperature, phonon and conduction electron contributions as well as a magnetic contribution to the heat capacity have been determined from heat capacity measurements. The magnetocaloric effect and the refrigerant cooling power for selected solid solutions was determined in magnetic fields up to 4.2 T. (C) 2015 Elsevier B.V. All rights reserved.

Specific heat measurements have been performed on polycrystalline HoCo 2 , ErCo 2 and their solid solutions Ho 1− x Er x Co 2 (0.1≤ x ≤0.5). These compounds were synthesized using high-purity rare-earth metals and cobalt. X-ray diffraction patterns taken at room temperature reveal that all compounds have the C15 cubic Laves phase structure. Heat capacity measurements have been performed in the temperature range of 2–300 K without magnetic field and in a magnetic field of 1 and 2 T. The magnetocaloric effect has been estimated in terms of isothermal magnetic entropy change for all solid solutions in magnetic fields up to 2 T. The effect of increasing Er amount in Ho 1− x Er x Co 2 on the magnetic and magnetocaloric properties will be discussed.

We present the result of high-field (up to 40T) galvanomagnetic study of bismuth bicrystals with nano-width crystallite interfaces (∼100nm). At B>2T directed along the interface plane in the quantum oscillations spectrum of the longitudinal Hall effect, two new harmonics have been detected. Their periods of oscillation characterise the much larger cross-sectional areas of Fermi surface of charge carriers than it is in single crystalline bismuth. At the same time, in small disorientation angle bicrystals of an inclination type, a number of Hall quasi-plateaus were observed, which vanish by reversing the magnetic field. We conclude that in bicrystals there are spin-oriented carriers that are located in spectrum of Landau levels at the particular orientation of the magnetic field.

Resistance and magnetoresistance of Si microwires were studied in temperature range 4,2-300 K at magnetic fields up to 14 T. Ga-In gates were created to wires and ohmic I-U characteristics were observed in all temperature range. It was found high elastic strain for Si wires, linear thermoresistive characteristics as well as small magnitude of magnetoresistance (of about 5% at 14 T), which was used to design multifunctional sensor of simultaneous measurements of strain and temperature with minimal sensitivity to magnetic field intensity.

The paper presents a study of the polymer dispersed liquid crystals that consist of liquid crystal 4-trans-4'-n-hexyl-cyclohexyl-isothiocyanatobenzene (6CHBT) microdroplets dispersed in polyvinyl alcohol and doped with various kinds of magnetic particles. As magnetic nanoparticles there were used single walled carbon nanotubes and magnetite labeled single walled carbon nanotubes. The volume concentration of the particles was 2 x 10(-3). Magnetic properties were investigated by a SQUID magnetometer. The higher saturation magnetization has been achieved in sample polymer dispersed liquid crystal doped with magnetite labeled single walled carbon nanotubes. The phase transition temperature from isotropic to nematic phase at the external magnetic field 0 T and 12 T was monitored by precise capacitance measurements in the capacitance cell filled with prepared sample. The significant shift of the phase transition temperature (0.2 degrees C) at the external magnetic field 12 T has been observed in sample polymer dispersed liquid crystal doped with magnetite labeled single walled carbon nanotubes.

Complex studies of strain induced effects in boron doped p-type silicon whiskers with [111] crystallographic direction in the wide temperature range 4.2 - 300 K at magnetic fields up to 14 T and under high-energy electron irradiation were carried out. The peculiarities of piezomagnetoresistance of Si whiskers heavily boron doped and with boron concentration in the vicinity of metal-insulator transition were determined. The influence of electron irradiation with energy 10 MeV and fluence Phi = 5-10(17) el/cm(2) on the gauge factor of boron doped Si whiskers at low temperatures have been also studied. High-sensitive piezoresistive sensor to measure pressure of liquid helium on the basis of silicon whiskers with a giant gauge factor was developed. Heavily doped Si whiskers with classic piezoresistance have been successfully used in mechanical sensors operating in the wide temperature range 4.2 - 300 K.

This paper presents a review and a comparison of the influence of Sc on some physical properties of R1-xScxNi2 (R = Gd, Tb, Dy, Ho) solid solutions. The X-ray diffraction studies performed at room temperature have allowed us to reveal that all R1-xScxNi2 solid solutions solidify with the formation of a Laves-phase superstructure corresponding to the F (4) over bar 3m space group. The magnetic properties are dominated by ferromagnetism of the rare earth atoms. While, upon substitution, non-magnetic Sc causes a dilution of magnetic moments on the rare earth site, resulting in a decrease of the ordering temperature. In the case of Gd1-xScxNi2, Tb1-xScxNi2 and Dy1-xScxNi2, the ferromagnetic order retains as the scandium content increases to x = 0.8, whereas, for Ho1-xScxNi2, the magnetic order manifests itself only for the solid solutions with x <= 0.6. The Debye temperature, phonon and conduction electron contributions as well as the magnetic contribution to the heat capacity have been determined from heat capacity measurements. The magnetocaloric effect for selected solid solutions was determined in magnetic fields up to 1 T. (C) 2012 Elsevier Ltd. All rights reserved.

We report magnetic and magnetocaloric properties of polycrystalline series of the (Ho0.9Er0.1)1-xGdxCo2(x = 0.05, 0.1 and 0.15) solid solutions. These samples were synthesized using high purity rare earth metals and cobalt. X-ray diffraction patterns taken at room temperature reveal that all compounds have the C15 cubic Laves phase structure. Magnetization measurements were carried out using a vibration sample magnetometer with a step motor in fields up to 14 T using a Bitter-type magnet. Heat capacity measurements have been performed in the temperature range of 2-300 K without magnetic field and in a magnetic field of 1 and 2 T. The magnetocaloric effect has been estimated in terms of isothermal magnetic entropy change for all solid solutions in magnetic fields up to 3 T. The effect of increasing Gd amount in (Ho0.9Er0.1)1-xGdxCo2on the magnetic and magnetocaloric properties will be discussed.

Magnetic and heat capacity measurements have been carried out on polycrystalline Dy1-xErxCo2 solid solutions (0 <= x <= 0.3). Powder X-ray diffraction at room temperature revealed that all Dy1-xErxCo2 solid solutions consist of the C15 cubic Laves phase MgCu2 type structure. These solid solutions are ferromagnetic with a Curie temperature Tc below 138 K. Their Curie temperatures decrease from 138 K for DyCo2 to 106 K for Dy0.7Er0.3Co2. At higher temperatures, all solid solutions are Curie-Weiss paramagnets. Both magnetic and heat capacity measurements showed that all samples undergo a first-order type Phase transition at Tc from paramagnetic to ferromagnetic state. Heat capacity measurements allowed us to determine the Debye temperature. The magnetocaloric effect has been estimated both in terms of isothermal magnetic entropy change and adiabatic temperature change in magnetic fields up to maximum 3 T. (C) 2011 Elsevier Ltd. All rights reserved.

The purpose of this work was the investigation of magnetostriction near magnetic phase transition paramagnetism-ferrimagnetism in ferrimagnetic intermetallic compound ErCo2. It is known that 3d-electrons are delocalized and form a 3d-zone in it, whereas 4f-electrons localized and create an effective exchange field which acts on the Co sublattice. It leads to magnetic ordering of the last. We have found there is a sharp jump in the curve of thermal expansion near T = 37K, which indicates the presence of first order phase transition. Volume magnetostriction omega reach huge values (3.10(-3) in the field mu H-0 = 4T near T-C). At temperatures T > T-C lambda(parallel to) and lambda(perpendicular to) have small values in the absence of an external magnetic field. However, in fields H> H-crit lambda(parallel to) and lambda(perpendicular to) rapidly increase and get the values that have the same order of magnitude as at T. TC. This indicates that the external magnetic field can restore the magnetism of 3d-subsystem at T>T-C.

Ferromagnetic compound NdCo2 has complex magnetic transformation, which are accompanied by changes of the crystal lattice. The purpose of this paper was the investigation of influence of these transformations on the field and temperature dependence of magnetostriction. It was found that near the Curie temperature Tc = 98K, where the transition from cubic to tetragonal phase is observed, there is a maximum in the temperature dependence of the transverse magnetostriction. lambda perpendicular to(T) in the field B=4T. In this field. lambda perpendicular to reaches high values of. lambda perpendicular to similar to 200 center dot 10(-6) at temperatures higher than T-c. This shows that in this field, the tetragonal distortion and band magnetism of 3d-subsystem remain even at T>Tc. At T<42K lambda perpendicular to decreases in field B=0.5 T due to phase transition from tetragonal phase to orthorhombic. The curve lambda perpendicular to (H) at T = 10 K anomalies are observed. They are associated with the fact that under the action of the external field there are consistent transitions from orthorhombic phase to tetragonal and then to cubic. Thus, it was found that the compound NdCo2 crystal structure is reconstructed with magnetic field.

Intermetallic compounds (Tb(0.45)Dy(0.55))(1-x)Er(x)Co(2) (x = 0.1; 0.2) were synthesized using high purity rare-earth metals. Multicomponent compositions with compensated magnetic anisotropy (MA) were chosen with respect to theoretical predictions based upon the single-ion MA model. Magnetostriction was measured in magnetic fields up to 10 T within the temperature range of 1.5-200 K by means of strain gauges. In the vicinity of magnetic phase transitions (160-170 K), giant volume magnetostriction (similar to 2x10(-3) in 10 T) provided by the band magnetism of a Co sublattice was observed in the compounds studied.

We report magnetic and magnetocaloric properties of the polycrystalline series of (Dy0.6Er0.4)(1-x)GdxCo2 (x = 0.2, 0.3 and 0.4) intermetallic compounds. These samples were synthesized using high purity rare earth metals. X-ray diffraction patterns taken at room temperature revealed that all the (Dy0.6Er0.4)(1-x)GdxCo2 compounds have the C15 cubic Laves phase superstructure. Magnetization measurements were carried out using a vibration sample magnetometer with a step motor in applied fields up to 14 T using a Bitter-type magnet. Heat capacity measurements have been performed in temperature range 2-300 K. The Debye temperatures, phonon and conduction electron contributions as well as the magnetic part of heat capacity were estimated. The magnetocaloric effect has been estimated both in terms of isothermal magnetic entropy change and adiabatic temperature change for selected solid solutions in magnetic fields up to 3 T. The raising amount of the Gd in samples on magnetic and magnetocaloric properties will be discussed.

Magnetic and heat capacity measurements have been carried out on the polycrystalline Gd1−xScxNi2 solid solutions (0≤x≤1), which crystallize in the cubic C15 Laves phases superstructure (space group F4−3m). These solid solutions are ferromagnetic with a Curie temperature below 76K. Their Curie temperature decreases from 75.4K for GdNi2 to 13.6K for Gd0.2Sc0.8Ni2. At high temperatures, all solid solutions, except ScNi2, are Curie–Weiss paramagnets. The Debye temperature as well as phonon, conduction electron and magnetic contributions to the heat capacity have been determined from heat capacity measurements. The magnetocaloric effect has been estimated both in terms of isothermal magnetic entropy change and adiabatic temperature change for selected solid solutions in magnetic fields up to 3T.

Magnetic and specific heat measurements have been performed on polycrystalline TbNi2, ScNi2 and their solid solutions Tb1-xScxNi2 (x = 0 1, 0 2) These compounds were synthesized using high-purity rare-earth metals It has been found that the magnetic susceptibility of the nonmagnetic ScNi2 compound exhibits a very weak temperature dependence characteristic of the Pauli paramagnets TbNi2, Tb-0 Sc-9(0) Ni-1(2) and Tb-0 Sc-8(0) Ni-2(2) are typical Curie-Weiss paramagnets and are ferromagnetically ordered below 36 K As revealed by room-temperature X-ray powder diffraction all the Tb1-xScxNi2 solid solutions have the cubic Laves C15-type superstructure The Debye temperature, phonon and conduction electron contributions as well as the magnetic part of heat capacity were determined The magnetocaloric effect has been studied by means of specific heat measurements in magnetic fields of 0 42 and 1 T The effect of rare-earth substitution in ScNi2 on the magnetic and magnetocaloric properties will be discussed

X-ray diffraction, magnetization, magnetic susceptibility, and heat capacity data are reported for the solid solutions Dy1−xScxNi2 (0 ≤ x ≥ 1). All the Dy1−xScxNi2 solid solutions are single phase with the C15 cubic Laves phase superstructure. The alloys with x ≤ 0.8 are ferromagnets with a low (below 22 K) Curie temperature that decreases from 21.1 K for DyNi2 to 4.5 K for Dy0.2Sc0.8Ni2. Dy0.1Sc0.9Ni2 and ScNi2 have no long-range magnetic order down to 2 K. At high temperatures, all the Dy1−xScxNi2 solid solutions, except ScNi2, are Curie–Weiss paramagnets. The Debye temperature, phonon and conduction electron contributions as well as a magnetic contribution to the heat capacity have been determined from heat capacity measurements. The magnetocaloric effect for selected solid solutions was determined in magnetic fields up to 3 T.

We report magnetic and magnetocaloric properties of the polycrystalline series of Dy 1− x Gd x (Co 1− x Ni x ) 2 ( x =0.1, 0.2, 0.3, 0.4 and 0.5) solid solutions. The samples were characterized by powder X-ray diffraction patterns taken at room temperature and revealed that all the Dy 1− x Gd x (Co 1− x Ni x ) 2 solid solutions consist of the C15 cubic Laves phase MgCu 2 type structure and a small amount of DyCo 3 and Dy 2 O 3 impurity phases. Magnetic measurements showed that the samples undergoes a second-order type phase transition at T C <130 K, from paramagnetic to ferromagnetic state. Heat capacity measurements have been performed for all solid solutions and allowed us to determine the Debye temperature. The magnetocaloric effect has been studied by means of specific heat measurements in magnetic field 0.42, 1 and 2 T. The GdNi 2 substitution effect on magnetic and magnetocaloric properties will be discussed.