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Magnetic refrigeration technology based on the magnetocaloric effect (MCE) of magnetic substances has been considered a prominent, energy‐efficient, and environmentally benign cooling method. Exploring suitable magnetic substances is a prerequisite for practical applications. A family of rare‐earth‐free magnetocaloric materials called Mn30Fe20−xCuxAl50 alloys is identified room‐temperature refrigeration, which are derived from the well‐known MnAl‐based permanent magnets. As expected from experimental and theoretical investigations, all of the Mn30Fe20−xCuxAl50 alloys are crystallized in a stable cubic CsCl‐type crystal structure, revealing a single second‐order type magnetic phase transition (MPT) with tunable MPT temperature. They also exhibit a large reversible MCE and good magnetocaloric performances in a wide temperature range. Crucially, these Mn30Fe20−xCuxAl50 alloys represent a rare case of magnetic materials belonging to a large family that can be fabricated from low‐price, earth‐abundant, and non‐toxic elements. They could provide new choices for practical room‐temperature magnetic refrigeration applications. [ABSTRACT FROM AUTHOR]

Reported here is a systematical investigation on the crystal structure, magnetic properties and magnetocaloric (MC) effect of three rare earth (RE) molybdate RE 2 MoO 6 (RE = Dy, Tb and Gd) oxides. The X-ray powder diffraction and the morphology as examined using the scanning electron microscope indicate phase-pure and polycrystalline nature of these oxides. The temperature (2–100 K) and magnetic field (up to 5 T) dependence of the magnetic measurements determine the magnetic phase transition (MPT) and MC properties. All the present RE 2 MoO 6 oxides crystallize in a monoclinic structure belonging to C 2/ c space group with the antiferromagnetic ordering at low temperature. Moreover, the RE 2 MoO 6 oxides hold reasonable values of MC parameters including the maximum isothermal magnetic entropy change/temperature-averaged entropy change (2 K lift) and relative cooling power values have been evaluated with the magnetic change of 0–5 T, yielding 17.22 (17.08) J/kgK and 277.67 J/kg for Dy 2 MoO 6 , 17.03 (16.83) J/kgK and 261.12 J/kg for Tb 2 MoO 6 , as well as 27.68 (26.69) J/kgK and 228.14 J/kg for Gd 2 MoO 6 , respectively. These acceptable MC parameters make the present RE 2 MoO 6 oxides potential candidates for cryogenic magnetic refrigeration (MR). [ABSTRACT FROM AUTHOR]

Abstract It is well known that rare earth (RE) based intermetallic compounds reveal various interesting magnetic properties depending on the crystallized structures and the constituent elements, paving the way for potential applications in different fields. Recent progresses regarding magnetic properties and magnetocaloric effect (MCE) in ternary rare earth RE 2 T 2 X (RE = Gd-Tm; T = Cu, Ni, Co; and X = Cd, In, Ga, Sn, Al) intermetallic compounds are reviewed in this paper. Some of them exhibit excellent MCE performances which make them attractive in the field of magnetic refrigeration at low temperature. With the aim of understanding the magnetocaloric characteristics of RE 2 T 2 X compounds, the crystal structure, magnetism and magnetic phase transition are also focused. The origin of the MCE together with the physics behind and the potential application of RE 2 T 2 X compounds are thoroughly considered. Highlights • Magnetic and magnetocaloric properties in RE 2 T2X compounds are reviewed. • The RE 2 T2X compounds show four types of crystallize structures. • Some of them exhibit excellent cryogenic magnetocaloric performances. • The origin of magnetocaloric effect in RE 2 T2X compounds is discussed. [ABSTRACT FROM AUTHOR]

The magnetic properties and magnetic entropy change of amorphousized Tm 60 Co 20 Ni 20 ribbon were systematically studied. The results indicate that the Tm 60 Co 20 Ni 20 amorphous ribbon reveals a second order magnetic transition (paramagnetic to ferromagnetic state) based on the Arrott plots and rescaled magnetic entropy change curves. A large magnetic entropy change is achieved around its Curie temperature of T C ∼6.7 K. Under the magnetic field change (Δ Η ) of 0–5 T, the maximum values of magnetic entropy change (−Δ S M max ) and relative cooling power ( RCP ) are 17.1 J/kg K and 273 J/kg, respectively. In particular, under a relative low Δ Η of 0–2 T, a large magnetic entropy change of 11.8 J/kg K reaches, making it attractive in the field of low-temperature magnetic refrigeration. [ABSTRACT FROM AUTHOR]

We reported the magnetism, magnetic phase transition behavior and magnetocaloric effect of the ternary Dy 2 CuSi 3 and Ho 2 CuSi 3 compounds. A second order magnetic phase transition from a paramagnetic (PM) to ferromagnetic (FM) state around their respective Curie temperatures were confirmed by using the magnetic measurements and rescaled magnetic entropy change curves in both compounds. A large magnetic entropy change was obtained with the absence of thermal and magnetic hysteresis loss in both compounds. The maximal magnetic entropy change (-Δ S M max ) reach 18.3 and 28.3 J/kg K for a magnetic field change of 0–70 kOe in Dy 2 CuSi 3 and Ho 2 CuSi 3 , respectively. The corresponding values of relative cooling power ( RCP ) are evaluated to be 460 J/kg and 627 J/kg, respectively. [ABSTRACT FROM AUTHOR]

The magnetic properties and magnetocaloric effect (MCE) in antiferromagnetic non-superconducting TbNiBC compound have been investigated in detail. Under low magnetic field changes and at low temperatures, the studied compound shows an inverse MCE which is due to the fact of antiferromagnetic ground state, whereas a normal reversible MCE under high magnetic field changes is observed which is related to the field-induced first-order metamagnetic transition from antiferromagnetic to ferromagnetic states. For the magnetic field change of 0-7 T the values of maximal magnetic entropy change ( $-\Delta S_{\mathrm {M}}^{\max } )$ , refrigerant capacity (RC) and relative cooling power (RCP) for the present TbNiBC are evaluated to be 11.1 J/kg/K, 225 J/kg and 296 J/kg, respectively. [ABSTRACT FROM AUTHOR]

The magnetic properties and magnetocaloric effect (MCE) in the ternary intermetallic compound of EuAuGe have been investigated. The compound undergoes a second-order magnetic phase transition at its own Curie temperatures T∼33 K. A large reversible table-like MCE has been observed from 1 to 40 K, which is related to the magnetic field-sensitive magnetic phase transition. For the magnetic field changes of 0-5 and 0-7 T, the maximum values of magnetic entropy change ( $-{\Delta } S_{\mathrm {M}}^{\max }$) are evaluated to be 7.6 and 10.1 J kg K, respectively; the corresponding relative cooling power ( RCP) are 358 and 499 J kg. The present results indicate that the EuAuGe compound is a considerable candidate for low-temperature refrigeration. [ABSTRACT FROM AUTHOR]

The magnetic properties and magnetocaloric effect (MCE) in Dy 2 Cu 2 In compound have been investigated. Dy 2 Cu 2 In undergoes two magnetic phase transitions, a paramagnetic to ferromagnetic (FM) at T C ∼ 49.5 K followed by a spin reorientation (SR) at T SR ∼ 19.5 K. For a magnetic field change of 0–7 T, the maximum values of the magnetic entropy change (−Δ S M max ) are estimated to be 16.5 around T C and 6.7 J/kg K around T SR with a large relative cooling power ( RCP ) value of 617 J/kg. The modified Arrott plots and universal curves of the rescaled Δ S M confirmed that the magnetic phase transitions in Dy 2 Cu 2 In compound belongs the second order phase transitions. The present results may provide some clues to search for new magnetocaloric materials belonging to RE 2 T 2 X system. [ABSTRACT FROM AUTHOR]

The magnetocaloric effect (MCE) of quaternary intermetallic compound ErNiBC has been investigated by magnetization and heat capacity measurements. The compound undergoes a paramagnetic (PM) to ferromagnetic (FM) transition at T C ~5 K and the ground state of Er ion forms a Kramer's doublet state. The magnetic transition is found to be second order in nature. The maximum magnetic entropy change (−Δ S M max ) and adiabatic temperature change (Δ T ad max ) of ErNiBC are 24.8 J/kg K and 8.6 K, respectively, for a magnetic field change of 0–50 kOe, and the corresponding refrigerant capacity ( RC ) is 312 J/kg. [ABSTRACT FROM AUTHOR]

The magnetic refrigeration (MR) based on magnetocaloric effect (MCE) is a key technique, since it possesses ideally higher performance than the traditional gas compression technology. However, the lack of MR materials with excellent MCE performance is a bottle-neck for practical MR applications. Herein, we systematically report the structural properties using powder X-ray diffraction and scanning electron microscope as well as the magnetic and magnetocaloric properties through the magnetization measurements of four rare-earth (RE) ruthenate RE 3 RuO 7 (RE = Pr, Nd, Gd and Tb) compounds. Light RE -based Pr 3 RuO 7 and Nd 3 RuO 7 compounds form an orthorhombic Cmcm structure, while heavy RE based Gd 3 RuO 7 and Tb 3 RuO 7 compounds crystallize in an orthorhombic P 2 1 nb structure. The magnetic phase transition of all the present compounds are confirmed to be of the first-order type with T N of 52, 15, 11 and 12 K for Pr 3 RuO 7 , Nd 3 RuO 7 , Gd 3 RuO 7 and Tb 3 RuO 7 compounds, respectively. The related MCE parameters including the maximum isothermal magnetic entropy change, temperature-averaged entropy change (5 K lift), and refrigerant capacity with the magnetic field change of 0–5 T were computed to be 1.35 J/kgK, 1.31 J/kgK, and 27.4 J/kg for Pr 3 RuO 7 , to be 2.18 J/kgK, 2.04 J/kgK, and 25.6 J/kg for Nd 3 RuO 7 , to be 8.12 J/kgK, 7.90 J/kgK, and 124.6 J/kg for Gd 3 RuO 7 , and to be 7.78 J/kgK, 7.49 J/kgK, and 128.8 J/kg for Tb 3 RuO 7 , respectively. [ABSTRACT FROM AUTHOR]

CsCl-type HoZn undergoes two successive magnetic phase transitions: (i) paramagnetic to ferromagnetic (FM) at T C ∼ 72 K and (ii) a spin reorientation (SR) at T SR ∼ 26 K. Magnetization and modified Arrott plots indicate that HoZn undergoes a second-order magnetic phase transition around T C . The obtained critical exponents have some small deviations from the mean-field theory, indicating a short range or a local magnetic interaction which is properly related to the coexistence of FM and SR transitions at low temperature. Two successive magnetic transitions in HoZn induce one broad pronounced peak together with a shoulder in the temperature dependence of the magnetic entropy change −Δ S M ( T ) curves, resulting in a wide temperature range with a large relative cooling power ( RCP ). For a field change of 0–7 T, the maximum value of −Δ S M is 15.2 J/kg K around T C with a large RCP value of 1124 J/kg. The large reversible magnetocaloric effect (MCE) and RC indicate that HoZn is a good candidate for active magnetic refrigeration. [ABSTRACT FROM AUTHOR]

We herein fabricated the (Dy 0.25 Ho 0.25 Er 0.25 Tm 0.25) 2 Cu 2 In high-entropy (HE) compounds and systematically determined its structural, magnetic, and magnetocaloric properties. The (Dy 0.25 Ho 0.25 Er 0.25 Tm 0.25) 2 Cu 2 In HE compound was found to crystalize in a tetragonal Mo 2 B 2 Fe type structure (P4/ mbm space group) and undergoes typical second order type magnetic transition. Large MCE and prominent cryogenic magnetocaloric performances were observed in (Dy 0.25 Ho 0.25 Er 0.25 Tm 0.25) 2 Cu 2 In HE compound. The evaluated values of magnetic entropy change and refrigerant capacity of (Dy 0.25 Ho 0.25 Er 0.25 Tm 0.25) 2 Cu 2 In HE compound under magnetic field change of 0–7 T are 17.1 J/kgK and 398.0 J/kg which are comparable with the reported candidate materials for cryogenic magnetic cooling, making the present (Dy 0.25 Ho 0.25 Er 0.25 Tm 0.25) 2 Cu 2 In HE compound also considerable for practical applications. • The (Dy 0.25 Ho 0.25 Er 0.25 Tm 0.25) 2 Cu 2 In HE compound was fabricated. • The structural, magnetic, MPT and MC properties were investigated. • The present HE compound is considerable for cryogenic magnetic cooling. [ABSTRACT FROM AUTHOR]

In this study, two Mo 2 FeB 2 -type multiple rare-earth-containing MRE 2 Cu 2 In (MRE = Dy 1/3 Ho 1/3 Er 1/3 and Ho 1/3 Er 1/3 Tm 1/3 ; space group P 4/ mbm , No. 127) compounds are prepared via arc-melting method and systematically determined regarding their structural and magnetic properties, magnetic phase transition (MPT), and magnetocaloric (MC) performances. They undergo typical second-order MPT at low temperatures. The MC effect and MC performances of the present MRE 2 Cu 2 In compounds at low temperatures are assessed using magnetic entropy changes, refrigerant capacity, and temperature-averaged entropy changes. The values of these parameters are comparable to most updated candidate materials for low-temperature magnetic cooling, making the present MRE 2 Cu 2 In compounds considerable for practical applications. • The MRE 2 Cu 2 In (MRE = Dy 1/3 Ho 1/3 Er 1/3 and Ho 1/3 Er 1/3 Tm 1/3) compounds are fabricated. • The structural, magnetic, MPT and MC properties in MRE 2 Cu 2 In were studied. • These MRE 2 Cu 2 In compounds are considerable for cryogenic magnetic refrigeration. [ABSTRACT FROM AUTHOR]

• The gallides RE 2 Rh 3 Ga (RE = Gd, Dy, Ho, Er) compounds are fabricated. • The structural, MPT and magnetocaloric properties in RE 2 Rh 3 Ga were studied. • The present RE 2 Rh 3 Ga compound are considerable for cryogenic MR. We herein provide an experimental investigation of the gallides RE 2 Rh 3 Ga (RE = Gd, Dy, Ho, Er) regarding their magnetic properties and magnetocaloric effect (MCE). All of these RE 2 Rh 3 Ga intermetallic compounds crystallized with the Mg 2 Ni 3 Si type structure, space group R– 3 m and are ordered magnetically at low temperatures. Large reversible MCEs around their own ordering temperature were observed in all RE 2 Rh 3 Ga compounds and their magnetocaloric parameters including the maximum magnetic entropy change, refrigerant capacity, and temperature-averaged entropy change are comparable to those of some recently reported candidate materials with prominent performances, making them considerable for cryogenic MR applications. [ABSTRACT FROM AUTHOR]

Rare earth (RE) based RE - TM - X (TM = transition metal elements; X = P - block elements) materials have received continuous attention due to the exhibition of various intriguing magnetic functional characteristics. In this work, a combined experimental and theoretical investigation has been conducted in detail for RE Co 12 B 6 (RE = Ce, Pr, Nd) compounds with regard to their structural and magnetic properties, particularly the magnetocaloric effect and magnetic phase transition (MPT). All of the present RE Co 12 B 6 compounds are found to crystalize in the SrNi 12 B 6 -type structure and with a ferrimagnetic ground state, which is confirmed by density functional theory calculations and magnetization measurements. The magnetic moments of RE atoms and Co atoms tend to be in antiparallel alignment, and the MPT of these materials originates primarily from the spin-polarized 3 d electrons of the Co atoms, which can be greatly affected by the 4 f electrons of RE atoms. Considerable magnetocaloric effects have been observed around its own T C of 130, 157, and 160 K, for CeCo 12 B 6 , PrCo 12 B 6 , and NdCo 12 B 6 , respectively, which is related to a typical second-order MPT. The corresponding maximum magnetic entropy change and relative cooling power values,with field changes of 0–70 kOe, are determined to be 2.54, 2.84, and 2.77 J/kg K and 116.8, 156.2, and 155.1 J/kg, respectively. The MPT properties of present RE Co 12 B 6 compounds were studied in further detail by critical analysis using the modified Arrott Plot and Kouvel-Fisher methods, which can be explained within the frame of the 3D Heisenberg model with short-range magnetic interaction. [Display omitted] [ABSTRACT FROM AUTHOR]