Rare Earth Intermetallic Compounds Research Articles

Effect of Hydrogenation on the Magnetic and Magnetocaloric Properties of Rare Earth Intermetallic Compounds Tb0.33Ho0.33Er0.33Ni and Dy0.33Ho0.33Er0.33Ni

Effect of Hydrogenation on the Magnetic and Magnetocaloric Properties of Rare Earth Intermetallic Compounds Tb0.33Ho0.33Er0.33Ni and Dy0.33Ho0.33Er0.33Ni

Estimation of magnetocaloric effect in multicomponent material Gd0.2Tb0.2Dy0.2Ho0.2Er0.2Ni2: Exploring high-entropy design

Polycrystalline rare earth intermetallic compound Gd0.2Tb0.2Dy0.2Ho0.2Er0.2Ni2 has been synthesized by arc melting and it has MgCu2-type cubic crystal structure at 300 K (space group Fd-3m). Magnetization measurement on arc-melted Gd0.2Tb0.2Dy0.2Ho0.2Er0.2Ni2 reveals a paramagnetic to ferromagnetic transition at ∼32 K (TC). The TC is close to the average value of the ferromagnetic transition temperatures of the end member GdNi2, TbNi2, DyNi2, HoNi2 and ErNi2 compounds. Using the field-dependent magnetization data measured around TC, isothermal magnetic entropy change (ΔSm) has been estimated. A maximum value of ΔSmmax = −14.3 J kg−1 K−1 is obtained at 27.5 K for 5 T field change. This value is significant when compared to that in the parent RNi2 (R = Gd, Tb, Dy, Ho and Er) compounds. The multicomponent compound Gd0.2Tb0.2Dy0.2Ho0.2Er0.2Ni2 has also been prepared by melt-spinning under inert atmosphere. The melt-spun sample shows granular microstructure with an average grain size of ∼1 µm. It is found that the bulk magnetic properties are almost retained in the melt-spun sample and the magnetocaloric effect is nearly equal to that in arc-melted Gd0.2Tb0.2Dy0.2Ho0.2Er0.2Ni2. The relative cooling power is large and is about 568 J kg−1 and 531 J kg−1 for 5 T field change for the arc-melted and melt-spun Gd0.2Tb0.2Dy0.2Ho0.2Er0.2Ni2 samples respectively.

Interstitial nitrogen-modified Y2Fe16SiNy compounds towards enhanced high-frequency magnetic properties

The rapid development of information technology urgently requires high-frequency soft magnetic materials with excellent electromagnetic performance. Herein, we synthesized the disordered dual-phase Y2Fe16Si intermetallic compound and introduced nitrogen atoms into its interstitial crystal sites by the gas-solid reaction, remarkably improving its magnetic and electromagnetic properties. The significant magneto-volume effect generated by introduced nitrogen atoms increases the compound's magnetization and Curie temperature, leading to increased permeability of Y2Fe16Si-paraffin composites. Furthermore, the synergistic effect of the magneto-volume and the chemical bonding change the compound's electric polarization by charge neutralization, dramatically decreasing the permittivity of Y2Fe16Si-paraffin composites upon nitrogenation. The decreased permittivity and increased permeability enhance the impedance matching and magnetic loss capability of the composites. Besides, the introduction of interstitial nitrogen gives rise to a higher ratio of the out-of-plane to in-plane anisotropy field of Y2Fe16Si due to anisotropic lattice expansion, which combines with enhanced magnetization to raise the Snoek limit and operating frequency of the composites. Consequently, Y2Fe16SiNy-paraffin composites exhibit the maximum effective absorption bandwidth (EAB) of 5.84 GHz in a thickness of 1.2 mm, and the minimum reflection loss (RLmin) of –50.52 dB in a thickness of 1.5 mm covering the Ku-band, demonstrating strong absorption, broad EAB with thin thickness and high operating frequency. This work shows the superiority of the interstitial atom effect in the high-frequency electromagnetic field, and the effect is applicable and scalable for rare-earth Fe-based intermetallic compounds to develop excellent microwave absorbers.

Effect of Pressure on Elastic Constants and Related Properties of Rare-Earth Intermetallic Compound TbNiAl

Effect of Pressure on Elastic Constants and Related Properties of Rare-Earth Intermetallic Compound TbNiAl

Magnetic properties and magnetocaloric effect of a metallic triangular lattice antiferromagnetic DyAl2Ge2 single crystal

We report the synthesis, magnetic susceptibility, magnetization, electrical resistivity, heat capacity, and magnetocaloric properties of the metallic triangular lattice antiferromagnetic DyAl2Ge2 single crystal. High-quality rare-earth intermetallic compound DyAl2Ge2 single crystals were synthesized by the metallic flux method. DyAl2Ge2 crystallizes in a trigonal CaAl2Si2-type structure with Dy atoms forming a triangular lattice in the ab plane. The paramagnetic-antiferromagnetic transition occurs at 8 K, as determined by temperature dependencies of magnetic susceptibility and heat capacity. No observable hysteresis was found in the field-induced antiferromagnetic to the ferromagnetic metamagnetic transition of DyAl2Ge2. The electrical resistivity shows an overall metallic behavior with an upturn at the ordering temperature. For a magnetic field change of 0–70 kOe, the maximum magnetic-entropy change is −14.2 J kg−1 K−1 at 11 K and the relative cooling power is 327 J kg−1 with the applied magnetic field along the ab plane.

Uncommon Magnetism in Rare-Earth Intermetallic Compounds with Strong Electronic Correlations

Rare-earth intermetallic compounds are characterised by the presence of a long-range magnetic order due to the interaction of local magnetic moments periodically located within the crystal lattice. This paper considers the possibility of forming an ordered state in cases where there is no opportunity to observe the local moment of the f-electronic shell in a traditional sense. These are, first of all, systems with a singlet ground state, as well as systems with fast spin fluctuations caused by a homogeneous intermediate-valence state of a rare-earth ion. Extensive experimental studies of these effects using neutron diffraction, neutron spectroscopy, and high-pressure studies of the magnetic phase diagram are presented and analysed, and the corresponding microscopic model representations are discussed. In particular, the possible origin of long-range magnetic order in mixed-valence compounds is analysed.

The effect of the X (X = Gd, Eu, La) substitution center position Tb on electronic, magnetic, and mechanical properties of TbFe2 by the DFT

Intermetallic compounds possess magnetostrictive properties and a unique interest in magnetic field detection. Here, the X (X = Gd, Eu, La) doped TbFe2, binary rare earth intermetallic compound is investigated using density functional theory (DFT). The electronic, magnetic, and mechanical properties of X-doped TbFe2 are systematically explored and compared. Then, energy bands and density of states (DOS), confirm that the X-doped TbFe2 compounds are metallic. Moreover, the asymmetry of the spin energy band and the anti-symmetric DOS indicate that X-doped TbFe2 is still magnetic. Further, magnetic research shows the magnetic moment of Gd-doped TbFe2 is highest upto 88.37 μB, which is about 1.7 times than that of TbFe2. Additionally, the four compounds (TbFe2 and X-doped TbFe2) are mechanically stable. Moreover, in contrast to the brittleness of TbFe2, X-doped TbFe2 becomes ductile. Hence, X-doped TbFe2 has improved the magnetic and ductile properties,which enhance its magnetic detection capabilities.

Valence electron structures and thermal and magnetic properties of RCo5 (R=light rare earth) intermetallic compounds with medium- and high-entropy design at R site

RCo5-type (R=light rare earth) medium- and high-entropy intermetallic compounds, which are designed by random occupation of equiatomic multiple rare earth elements at the rare earth site, are prepared by arc melting and vacuum heat-treatment technologies, and their crystal structures and magnetic properties are studied by X-ray diffraction and magnetic measurements. The empirical electron theory of solids and molecules is used to investigate their valence electron structures, thermal and magnetic properties. The theoretical bond lengths and magnetic moments match the experimental ones well. The study reveals that the thermal and magnetic properties are strongly related to the valence electron structures modulated by medium- and high-entropy design at rare earth. The medium and high entropized designs induce the increase of the covalence electron numbers nc. It is helpful for stabilizing the crystal structure. The number of covalence electron pair of the strongest R-CoI bond affects the melting point. The magnetic moments of RCo5-type medium- and high-entropy intermetallic compounds, which mainly originate from the 3d magnetic electrons of Co atoms, are modulated by medium and high entropized rare earth due to their exchange interactions. The magnetic moment of Co at the 2c site is larger than that of Co at the 3g site, which is due to the electron transformations from magnetic to covalence electron for bonding with the rare earth at the 3g site. Curie temperatures raise with the increasing 3d magnetic electron numbers of Co atom.

Magnetic properties of a multicomponent intermetallic compound Tb$_{0.25}$Dy$_{0.25}$Ho$_{0.25}$Er$_{0.25}$Al$_2$

Polycrystalline multicomponent Laves phase rare earth intermetallic compound Tb_{0.25}0.25 Dy_{0.25}0.25Ho_{0.25}0.25Er_{0.25}0.25Al_{2}2 has been synthesized by arc-melting and characterized by powder X-ray diffraction, magnetization and heat capacity measurements. The sample has MgCu_22-type cubic structure (space group Fd-3m) at 300 K. The compound Tb_{0.25}0.25Dy_{0.25}0.25Ho_{0.25}0.25Er_{0.25}0.25 Al_{2}2 orders ferromagnetically at 50 K (T_CC). This value is almost equal to the average of the ferromagnetic ordering temperatures of the individual RAl_22 (R = Tb, Dy, Ho and Er) compounds. Field dependence of magnetization below T_CC indicates soft-ferromagnetic nature. From the magnetization vs field data obtained near T_CC and the temperature dependence of heat capacity, low field magnetocaloric effect has been estimated.

Designing magnetocaloric materials for hydrogen liquefaction with light rare-earth Laves phases

Magnetocaloric hydrogen liquefaction could be a ‘game-changer’ for liquid hydrogen industry. Although heavy rare-earth based magnetocaloric materials show strong magnetocaloric effects in the temperature range required by hydrogen liquefaction (77–20 K), the high resource criticality of the heavy rare-earth elements is a major obstacle for upscaling this emerging liquefaction technology. In contrast, the higher abundances of the light rare-earth elements make their alloys highly appealing for magnetocaloric hydrogen liquefaction. Via a mean-field approach, it is demonstrated that tuning the Curie temperature (T C) of an idealized light rare-earth based magnetocaloric material towards lower cryogenic temperatures leads to larger maximum magnetic and adiabatic temperature changes (ΔS T and ΔT ad). Especially in the vicinity of the condensation point of hydrogen (20 K), ΔS T and ΔT ad of the optimized light rare-earth based material are predicted to show significantly large values. Following the mean-field approach and taking the chemical and physical similarities of the light rare-earth elements into consideration, a method of designing light rare-earth intermetallic compounds for hydrogen liquefaction is used: tuning T C of a rare-earth alloy to approach 20 K by mixing light rare-earth elements with different de Gennes factors. By mixing Nd and Pr in Laves phase (Nd, Pr)Al2, and Pr and Ce in Laves phase (Pr, Ce)Al2, a fully light rare-earth intermetallic series with large magnetocaloric effects covering the temperature range required by hydrogen liquefaction is developed, demonstrating a competitive maximum effect compared to the heavy rare-earth compound DyAl2.

On the magnetic and magnetocaloric properties of rare earth intermetallic compound Tb0.33Ho0.33Er0.33Ni

Polycrystalline rare earth intermetallic compound Tb0.33Ho0.33Er0.33Ni has been synthesized by arc melting under argon atmosphere. Powder X-ray diffraction data suggest that the compound Tb0.33Ho0.33Er0.33Ni crystallizes in orthorhombic structure at 300 K (FeB-type, space group Pnma). Temperature variation of magnetization reveals paramagnetic to ferromagnetic cross-over around 59 K (TC). The TC is close to the average value of the ferromagnetic transition temperatures of TbNi, HoNi and ErNi compounds. Isothermal magnetization has been measured as a function of magnetic field up to 70 kOe and the magnetocaloric effect around TC has been calculated.

EFFECT OF PRESSURE ON ELASTIC CONSTANTS AND RELATED PROPERTIES OF RARE-EARTH INTERMETALLIC COMPOUND TBNIAL

The Lennard-Jones potential approach is used to investigate the effect of pressure on the ultrasonic and elastic properties of the rare-earth ternary TbNiAl intermetallic compound. The second- and third-order elastic constants of TbNiAl are considered using the potential model. The pressure-dependent higher-order elastic constants are studied, and it is observed that the elastic constants of the TbNiAl compound increased monotonously with pressure. The hexagonal TbNiAl compound is mechanically stable up to the pressure 20 GPa according to the Born elastic stability criteria. The Voigt-Reuss-Hill approach is used to compute such elastic parameters as Young’s modulus, bulk modulus, Poisson’s ratio, and shear modulus in the pressure range 0-45 GPa. Hardness, melting temperature, and anisotropy are also determined for the intermetallic TbNiAl compound. The pressure-dependent velocities and attenuation of ultrasonic waves in this ternary compound are evaluated. The computation results are also satisfactory in estimating the Debye temperature and thermal conductivity Kmin under different pressure. It is observed that TbNiAl has a significant anisotropy at zero pressure, which becomes stronger as the pressure increased. This ternary compound behaves as its purest form at higher pressure and is more ductile, which is demonstrated by the minimum attenuation.

Unusual first-order magnetic phase transition and large magnetocaloric effect in Nd2In

A large magnetocaloric effect with its maximum near the boiling point of natural gas occurs in a rare-earth intermetallic compound ${\mathrm{Nd}}_{2}\mathrm{In}$. While behaviors of physical properties indicate that paramagnetic-ferromagnetic transformation supporting the large magnetocaloric effect is first order in nature, temperature-dependent crystallographic study reveals no changes in lattice symmetry and lack of discontinuities either in phase volume or lattice parameters. The borderline first-order nature of phase transformation in ${\mathrm{Nd}}_{2}\mathrm{In}$ is markedly different from conventional first-order magnetic transitions occurring in other members of the family -- isostructural ${\mathrm{Pr}}_{2}\mathrm{In}$ and nonisostructural ${\mathrm{Eu}}_{2}\mathrm{In}$.

Anisotropic magnetic property, magnetostriction, and giant magnetocaloric effect with plateau behavior in TbMn2Ge2 single crystal

The ternary RMn2Ge2 (R = rare earth) intermetallic compounds have attracted great attention due to their interesting magnetic behaviors and magnetotransport responses. Here, we reported our observation of anisotropic magnetic property, magnetostriction, and magnetocaloric effect (MCE) in TbMn2Ge2 single crystal. Below the transition temperature of Tb magnetic sublattices (T_{{text{C}}}^{{{text{Tb}}}} ~ 95 K), strong Ising-like magnetocrystalline anisotropy is observed with an out-of-plane ferromagnetic moments 5.98 μB/f.u. along the easy c axis, which is two orders of magnitude larger than that of field along a axis. Above T_{{text{C}}}^{{{text{Tb}}}}, a field-induced metamagnetic transition is observed from the spin-flip of Mn sublattices. During this transition, remarkable magnetostriction effect is observed, indicating of strong spin–lattice coupling. The responses of Tb and Mn sublattices to the magnetic field generate a giant magnetic entropy change (- Delta S_{M}) and large values of relative cooling power (RCP) and temperature-averaged entropy change (TEC). The calculated maximum magnetic entropy change (- Delta S_{M}^{max }), RCP, and TEC(10) with magnetic field change of 7 T along c axis reach 24.02 J kg−1 K−1, 378.4 J kg−1, and 21.39 J kg−1 K−1 near T_{{text{C}}}^{{{text{Tb}}}}, which is the largest among RMn2Ge2 families. More importantly, this giant MCE shows plateau behavior with wide window temperatures from 93 to 108 K, making it be an attractive candidate for magnetic refrigeration applications.

Magnetic incommensurability, short-range correlations, and properties ofHo7Rh3

The crystal structure, thermal properties, and magnetic state of the rare-earth intermetallic compound ${\mathrm{Ho}}_{7}{\mathrm{Rh}}_{3}$ was studied using the measurements of the AC and DC magnetic susceptibility, magnetization, specific heat and thermal expansion, as well as by neutron and synchrotron powder diffraction. Below the N\'eel temperature ${T}_{\mathrm{N}}=32$ K, an incommensurate antiferromagnetic (AFM) structure of the spin density wave (SDW) type was observed, described by the magnetic superspace group $Cmc{2}_{1.}{1}^{\ensuremath{'}}(00g)0sss$ and the propagation vector ${\mathbf{k}}_{\mathrm{IC}}=(0\phantom{\rule{0.16em}{0ex}}0\phantom{\rule{0.16em}{0ex}}0.389)$. Further cooling leads to the spin reorientation transition and squaring-up transformation of the SDW magnetic structure below ${T}_{t1}=22$ K. The spin reorientation transition is accompanied by the emergence of a ferromagnetic component in the incommensurate magnetic structure upon cooling below ${T}_{t2}=9$ K. Using neutron diffraction, the existence of a short-range antiferromagnetic order was revealed up to temperatures twice as high as ${T}_{\mathrm{N}}$. These short-range AFM correlations were found to affect the magnetic susceptibility and thermal expansion, while the crystal structure retains its hexagonal symmetry below and above the N\'eel temperature.

Crystal structure and magnetism of rare earth intermetallic compound Dy0.33Ho0.33Er0.33Ni

Multi-component rare earth intermetallic compound Dy0.33Ho0.33Er0.33Ni has been prepared by arc melting and characterized by powder X-ray diffraction and magnetization experiments. The sample crystallizes in orthorhombic FeB-type structure at 300 K and ferromagnetically orders around 40 K (TC). The TC is close to the average value of the ferromagnetic transition temperatures of DyNi, HoNi and ErNi compounds. Magnetization has been measured as a function of field up to 15 kOe and low field magnetocaloric effect around the magnetic transition temperature is computed.

Intermetallic compounds RE 2Ga2Mg (RE = Tb–Tm, Lu) with Mo2B2Fe-type structure

Abstract The rare earth intermetallic compounds RE 2Ga2Mg with RE = Tb–Tm and Lu were synthesized from the elements in sealed tantalum ampoules in a high-frequency furnace. These rare earth-rich phases crystallize with the tetragonal Mo2B2Fe-type structure, space group P4/mbm and Z = 2. The polycrystalline samples were characterized through their Guinier powder patterns. The structures of Er2Ga2.092(1)Mg0.908(1), Tm2Ga2.037(1)Mg0.963(1) and Lu2Ga2.176(1)Mg0.824(1) have been refined from single crystal X-ray diffractometer data. The refinements revealed small homogeneity ranges (small degrees of Mg/Ga mixing on the 2a sites). The magnesium atoms show square planar coordination by Ga2 dumbbells (282 pm Mg–Ga and 257 pm Ga–Ga in the lutetium compound). Geometrically one can describe the RE 2Ga2Mg phases as 1:1 intergrowth structures of CsCl and AlB2-related slabs of compositions REMg and REGa2. From DFT based calculations, charge transfer from the rare earth and magnesium atoms towards gallium can be illustrated in electron localization function ELF slice planes showing strong localization around gallium in the basal plane as well as along the tetragonal c axis signaling Ga–Ga pair interactions. The site-projected density of states DOS and COOP data further quantify this observation. Temperature dependent magnetic susceptibility measurements show Pauli paramagnetism for Sc2Ga2Mg and Lu2Ga2Mg with low room temperature susceptibility values of 2.1(1) × 10−4 and 1.1(1) × 10−4 emu mol−1, respectively. Ho2Ga2Mg, Er2Ga2Mg and Tm2Ga2Mg are Curie-Weiss paramagnets with stable trivalent rare earth ground states. Antiferromagnetic ordering was detected below the Néel temperatures of T N = 18.6(1) (RE = Ho), 11.9(1) (RE = Er) and 6.4(1) K (RE = Tm). The three compounds show metamagnetic transitions in their 3 K magnetization isotherms. Tm2Ga2Mg exhibits a square loop behavior with small hysteresis.

Hybridization and correlation between f - and d -orbital electrons in a valence fluctuating compound EuNi2P2

The interaction between localized f and itinerant conduction electrons is crucial in the electronic properties of heavy fermion and valence fluctuating compounds. Using high-resolution angle-resolved photoemission spectroscopy, we systematically investigate the electronic structure of the archetypical valence fluctuating compound EuNi2P2 that hosts multiple f electrons. At low temperatures, we reveal the hybridization between Eu 4f and Ni 3d states, which contributes to the electron mass enhancement, consistent with the periodic Anderson model. With increasing temperature, interestingly, we observe opposite temperature evolution of electron spectral function above and below the Kondo coherence temperature near 110 K, which is in contrast to the monotonic valence change and beyond the expectation of the periodic Anderson model. We argue that both f-d hybridization and correlation are imperative in the electronic properties of EuNi2P2. Our results shed light on the understanding of novel properties, such as heavy fermion behaviors and valence fluctuation, of rare-earth transition-metal intermetallic compounds with multiple f electrons.

A mechanism for the strange metal phase in rare-earth intermetallic compounds

SignificanceThe elusive strange metal phase (ground state) was observed in a variety of quantum materials, notably in f-electron-based rare-earth intermetallic compounds. Its emergence has remained unclear. Here, we propose a generic mechanism for this phenomenon driven by the interplay of the gapless fermionic short-ranged antiferromagnetic spin correlation and critical bosonic charge fluctuations near a Kondo breakdown quantum phase transition. It is manifested as a fluctuating Kondo-scattering-stabilized critical (gapless) fermionic spin liquid. It shows [Formula: see text] scaling in dynamical electron scattering rate, a signature of quantum criticality. Our results on quasilinear-in-temperature scattering rate and logarithmic-in-temperature divergence in specific heat coefficient as temperature vanishes were recently seen in CePd[Formula: see text]NixAl.

Magnetocaloric effect in melt-spun rare earth intermetallic compound ErAl2

Laves phase rare earth intermetallic compound ErAl2 (Cubic, MgCu2-type) has been prepared by melt-spinning process. Analysis of powder X-ray diffraction data of melt-spun ErAl2 yields crystallite size of about 54 nm. Transmission electron microscopy image reveals particles of size ∼70 nm. The melt-spun ErAl2 orders ferromagnetically ∼10 K (TC) whereas the ferromagnetic ordering temperature is ∼14 K for the arc-melted ErAl2 compound. From the magnetization vs field data, isothermal magnetic entropy change (ΔSm) has been computed as a function of temperature near TC. The maximum ΔSm value in the melt-spun ErAl2 is ∼ −34 Jkg−1K−1 at 14 K for 70 kOe field change whereas the corresponding value in the arc-melted sample is ∼ −42 Jkg−1K−1 at 16 K. Thus, rapid solidification results in crystalline, coarse grained ErAl2 with submicron sized particles leading to only minor changes in the magnetic and magnetocaloric properties.