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In this paper, a detailed investigation with respect to the structural, cryogenic magnetic properties and magnetocaloric performances of RE 2 CuMnO 6 (RE = Gd, Dy, Ho and Er) double perovskite (DP) compounds has been performed. All the RE 2 CuMnO 6 compounds are confirmed to B -site disordered and crystallized in the GdFeO 3 -type structure (Pnma space group, N 62, oP20). The magnetic transition temperatures (T M) are found to be ~7.5 K for Gd 2 CuMnO 6 , ~12.1 K for Dy 2 CuMnO 6 , ~12.2 K for Ho 2 CuMnO 6 , and ~3.6 K for Er 2 CuMnO 6 , respectively. Moreover, for checking the magnetocaloric performances several vital parameters including -Δ S M max (peak value of magnetic entropy change, -Δ S M), TEC (3) (temperature averaged -Δ S M) and RCP (relative cooling powers) are evaluated to be 7.84, 7.73 J/kgK and 151.1 J/kg for Gd 2 CuMnO 6 , 5.69, 5.59 J/kgK and 180.9 J/kg for Dy 2 CuMnO 6 , 7.12, 7.05 J/kgK and 192.4 J/kg for Ho 2 CuMnO 6 , as well as 9.92, 9.60 J/kgK and 195.9 J/kg for Er 2 CuMnO 6 under the magnetic field change Δ H = 5 T, respectively. [ABSTRACT FROM AUTHOR]

In this study, we present the crystal structure, magnetic properties, and cryogenic magneto-caloric effect (MCE) of RE 2 FeAlO 6 (RE = Gd, Dy, Ho) oxides. The XRD refinement analysis suggests that all the RE 2 FeAlO 6 oxides are crystallized in B-site disordered orthorhombic structure. The RE 2 FeAlO 6 oxides exhibit large MCEs around T C. The peak magnetic entropy change (-Δ S M) and refrigeration capacity (RC) are 25.9 J/(kgK) and 240.1 J/kg for Gd 2 FeAlO 6 , 10.7 J/(kgK) and 274.9 J/kg for Dy 2 FeAlO 6 , 9.6 J/(kgK) and 249.6 J/kg for Ho 2 FeAlO 6 under Δ H of 0–70 kOe, respectively. Notably, Gd 2 FeAlO 6 exhibits promising magneto-caloric performance and therefore is a favorable candidate for cryogenic magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The rare-earths (RE) based amorphous materials with large magnetocaloric (MC) effects and excellent glass forming ability (GFA) have been recognized as promising candidates for magnetic refrigeration (MR). In this work, the RE 60 Co 20 Al 20 (RE = Ho, Er, Tm) amorphous ribbons were successfully fabricated and systematically determined with respect to the GFA, magnetic properties and MC effects. A second order magnetic phase transition (MPT) from ferromagnetic to paramagnetic (FM to PM) without noticeable field or thermal hysteresis has been observed around the Curie temperatures, T C ~ 22.3 K for Ho 60 Co 20 Al 20 , ~ 10.3 K for Er 60 Co 20 Al 20 , and ~ 5.0 K for Tm 60 Co 20 Al 20 , respectively. The MC parameters including the maximum magnetic entropy change (| Δ S M max |), temperature-averaged entropy change with 3 K lift [ TEC (3 K)], and relative cooling powder/refrigerant capacity (RCP/RC) have been determined to check the MC performances, and the corresponding values are determined to be 14.16, 15.57 and 15.06 J/kgK, to be14.04, 15.38 and 14.78 J/kgK, and to be 625.0/478.7, 505.7/391.8 and 334.0/243.4 J/kg for Ho 60 Co 20 Al 20 , Er 60 Co 20 Al 20 and Tm 60 Co 20 Al 20 under the field change Δμ 0 H = 5 T, respectively. The present results indicate that RE 60 Co 20 Al 20 (RE = Ho, Er, Tm) amorphous ribbons are considerable for cryogenic MR application. • The RE 60 Co 20 Al 20 (RE = Ho, Er, Tm) amorphous ribbons are fabricated. • The glass forming ability in RE 60 Co 20 Al 20 amorphous ribbons was investigated. • Large magnetocaloric effect in RE 60 Co 20 Al 20 has been observed. • RE 60 Co 20 Al 20 ribbons are considerable for cryogenic magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The ternary rare earth RE CoSi 2 (RE = Er and Tm) intermetallic compounds were synthesized by means of arc-melting technique and their crystal structure, magnetism and magneto-caloric effect (MCE) were studied systematically. Both ErCoSi 2 and TmCoSi 2 crystallize in a CeNiSi 2 -type structure (Cmcm space group) confirmed by FULLPROF Rietveld refinement. Magnetization data indicates the antiferromagnetic (AFM) ground state for both RE CoSi 2 compounds, and a magnetic field-induced ferromagnetic (FM) transition occurs below the Neel temperature T N ∼6.9 K for ErCoSi 2 and ∼5.4 K for TmCoSi 2. Considerable reversible MCE in ErCoSi 2 and TmCoSi 2 was observed. The MCE performances of RE CoSi 2 are evaluated by -Δ S M max (maximal magnetic entropy change), TEC (3) (temperature averaged entropy change), and RCP (relative cooling power) with the values of 7.1 J/kg K, 6.8 J/kg K and 165.9 J/kg for ErCoSi 2 , as well as 8.7 J/kg K, 8.5 J/kg K and 152.9 J/kg for TmCoSi 2 , respectively, under Δ H (field change) of 0–50 kOe. Image 1 • CeNiSi 2 -type RE CoSi 2 (RE = Er and Tm) compounds were fabricated. • AFM ordering at T N ∼6.9 K for ErCoSi 2 and ∼5.4 K for TmCoSi 2. • A field-induced AFM to FM transition for both compounds occur below T N. • Considerable values of -Δ S M max, TEC , RC and RCP were found. • RE CoSi 2 compounds are also considerable for cryogenic magnetic cooling. [ABSTRACT FROM AUTHOR]

The crystal structure together with the magnetic and magnetocaloric properties in RE 2 Ni 1.5 Ga 2.5 (RE = Dy, Ho, Er and Tm) have been investigated systematically. All the RE 2 Ni 1.5 Ga 2.5 compounds crystallize in a CaIn 2 -type structure of (P63/mmc space group). A second-ordered magnetic phase transition (SOPT) from ferromagnetic to paramagnetic (FM to PM) is occurred in RE 2 Ni 1.5 Ga 2.5 compounds with the Curie temperatures (T C) of approximately 16.1, 10.6, 4.1 and below 2 K for RE of Dy, Ho, Er and Tm, respectively. The magnetocaloric parameters including magnetic isothermal entropy change/temperature-averaged magnetic entropy change -Δ S M max/ TEC (5) and relative cooling power RCP are calculated with the values of 10.01/9.92 J/kg K and 418.6 J/kg for Dy 2 Ni 1.5 Ga 2.5 , 20.12/19.65 J/kg K and 644.1 J/kg for Ho 2 Ni 1.5 Ga 2.5 , 18.07/17.69 J/kg K and 447.1 J/kg for Er 2 Ni 1.5 Ga 2.5 , as well as 18.22/16.75 J/kg K and 330.7 J/kg for Tm 2 Ni 1.5 Ga 2.5 with magnetic field change (Δ H) of 0–7 T, respectively. Notably, Ho 2 Ni 1.5 Ga 2.5 exhibits ralatively high magnetocaloric parameters, which suggests that Ho 2 Ni 1.5 Ga 2.5 is a competitive candidate among the MCE materials in the field of cryogenic magnetic refrigeration (MR). • Magnetic properties and MCE in RE 2 Ni 1.5 Ga 2.5 compounds were studied. • Large values of -ΔS M max, TEC and RCP were observed at low temperature. • Ho 2 Ni 1.5 Ga 2.5 compound is competitive for cryogenic magnetic cooling. [ABSTRACT FROM AUTHOR]

We present a detailed investigation of the crystal structure, magnetism and magneto-caloric performances of RE Co 2 B 2 C (RE = Gd, Tb and Dy) compounds. All compounds are described with a LuNi 2 B 2 C-type crystallographic structure (I 4/ mmm space group). A second-ordered paramagnetic to ferromagnetic (PM-FM) transition is observed in RE Co 2 B 2 C compounds around their Curie temperatures (T C) of 17.2, 5.3 and 7.7 K, and induced a considerable magneto-caloric effect (MCE) for GdCo 2 B 2 C, TbCo 2 B 2 C and DyCo 2 B 2 C, respectively. The magneto-caloric performances for RE Co 2 B 2 C were characterized by the isothermal magnetic entropy (- Δ S M max) , temperature averaged entropy change (TEC) with three different temperature lifts (3, 5 and 10 K), and relative cooling power (RCP). The corresponding values of - Δ S M max , TEC (3 K) and RCP under the magnetic field change (Δ H) of 0–5 T, are 10.34 J/kg-K, 10.23 J/kg-K, and 238.1 J/kg for GdCo 2 B 2 C, 18.09 J/kg-K, 17.83 J/kg-K, and 438.2 J/kg for TbCo 2 B 2 C, as well as 17.79 J/kg-K, 17.72 J/kg-K, and 480.1 J/kg for DyCo 2 B 2 C, respectively. • Magnetic properties and MCE in RE Co 2 B 2 C compounds were studied. • Large values of -ΔS M max, TEC, RC and RCP were observed at low temperature. • RE Co 2 B 2 C compounds are competitive for cryogenic magnetic cooling. [ABSTRACT FROM AUTHOR]

In this work, polycrystalline oxides viz., Ho 2 CrMnO 6 (HCMO) and Er 2 CrMnO 6 (ECMO), were prepared using the sol-gel process, and their crystal structure, magnetic properties, and magnetocaloric effects (MCEs) were studied. X-ray refinement results demonstrate that both oxides exhibited the B -site disordered perovskite type structure (Pbnm space group). A ferromagnetic-paramagnetic phase transition as well as large reversible MCEs was also observed at Curie temperatures (T C) of ~6.1 and ~5.2 K for HCMO and ECMO, respectively. For a magnetic field change (ΔH) of 0–7 T, the maximum magnetic entropy change (-Δ S M), temperature-averaged entropy change (TEC 3), and relative cooling power (RCP) were estimated to be 11.03 J/kgK, 11.02 J/kgK, and 322.7 J/kg for HCMO, and 12.94 J/kgK, 12.80 J/kgK and 277.5 J/kg for ECMO. [ABSTRACT FROM AUTHOR]

The magnetic refrigeration (MR) by utilizing the magnetocaloric effect (MCE) of magnetic solids has been considered a promising, environmentally benign, energy-efficient cooling technology. However, the lack of promising magnetic substances has slowed the development of its active application. To identify suitable candidate materials, we herein identified the structural and magnetic properties together with the MCE and magnetocaloric performances of rare earth (RE) rich RE 6 Ni 2.25 Al 0.75 (RE = Dy, Ho and Er) compounds. All the RE 6 Ni 2.25 Al 0.75 compounds are confirmed to crystallized in orthogonal Ho 6 Co 2 Ga-type structure and underwent paramagnetic to antiferromagnetic magnetic transitions. Moreover, large direct (conventional) and inverse MCEs have been observed in all the RE 6 Ni 2.25 Al 0.75 compounds. The values of peak magnetic entropy changes, temperature-averaged magnetic entropy changes with 5 K-lift and relative cooling powers under magnetic field change of 0–7 T are evaluated to be − 4.44 J/kg-K, − 4.38 J/kg-K and 230.6 J/kg for Dy 6 Ni 2.25 Al 0.75 , to be − 12.68 J/kg-K, − 12.26 J/kg-K and 378.2 J/kg for Ho 6 Ni 2.25 Al 0.75 , and to be − 17.52 J/kg-K, − 17.33 J/kg-K and 465.7 J/kg for Er 6 Ni 2.25 Al 0.75 , respectively. • The RE6Ni2.25Al0.75 (RE = Dy, Ho and Er) compounds are fabricated. • The structural and magnetic properties were investigated. • Large direct and inverse magnetocaloric effects were observed. • The Er6Ni2.25Al0.75 is considerable for cryogenic magnetic refrigeration. [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]