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The rare-earth (RE)-based magnetic solids with large magneto-caloric effect (MCE) have been well investigated recently due to their potential applications in the field of environmentally friendly cryogenic magnetic refrigeration (MR). Herein, two polycrystalline RE-based REFe2Si2 (RE = Dy and Tb) intermetallic compounds have been prepared by an arc-melting way and determined with regard to the structural and magnetic phase transition (MPT) properties as well as the MCE and magneto-caloric performance. Both of the present REFe2Si2 compounds at room temperature are crystallized in a ThCr2Si2-type structure and undergo a first-ordered MPT from antiferromagnetic to paramagnetic state around the Néel temperature (TN) of ~ 4.05 K for DyFe2Si2 and ~ 6.25 K for TbFe2Si2, respectively. Large cryogenic MC effect together with excellent MC performance have been realized in DyFe2Si2 compound. The MC parameters with magnetic field change at 0–5 T of the maximum magnetic entropy changes and the refrigerant capacity/relative cooling power were found to be 16.08 J/kgK and 318.5/403.3 J/kg for DyFe2Si2 and to be 9.88 J/kgK and 105.9/140.8 J/kg for TbFe2Si2, respectively. [ABSTRACT FROM AUTHOR]

Two rare earth (RE)-based ternary intermetallic compounds, PrCu2Ge2 and NdCu2Ge2, have been synthesized and investigated with respect to the structure, magnetic phase transition and magnetocaloric (MC) properties. Both of the RECu2Ge2 compounds are found to be crystallized in the layered ThCr2Si2-type structure and reveal paramagnetic-to-antiferromagnetic transition at low temperature. Large reversible MC effects have been found and the maximum values of magnetic isothermal entropy change (− ΔSMmax) with the magnetic field change (ΔH) of 0–7 T are evaluated to be 5.36 J/kg K and 5.04 J/kg K for PrCu2Ge2 and NdCu2Ge2 compounds, respectively. [ABSTRACT FROM AUTHOR]

The crystal structure, magnetic properties and magnetocaloric performances of rare earth rich RE11Co4In9 (RE = Gd, Dy and Ho) intermetallic compounds are investigated systematically in this work. All compounds in this system crystallize in the orthorhombic Nd11Pd4In9-type structure with the Cmmm space group. The stacks of alternate RE and Co/In atomic layers with z = 0, 1 and z = 1/2 along the z-axis constitute the crystal structure. These compounds belong to the REx+yM2yXx family with x = 9 and y = 2, and the ratio of the AlB2-type and CsCl-type fragments in a unit cell is y : x, i.e. 2 : 9. The characteristic of multiple magnetic phase transition is revealed with a low magnetic flux density μ0H of 0.1 T for the present compounds. The ferromagnetic (FM) to paramagnetic (PM) phase transitions of the present compounds around their respective Curie temperatures (TC) are all second order phase transitions (SOPTs). Around the TC of 86, 37 and 20 K for Gd11Co4In9, Dy11Co4In9, and Ho11Co4In9 with a magnetic flux density change Δμ0H of 0–7 T, the values of the maximum magnetic entropy change (−ΔS maxM) and temperature averaged entropy change (TEC) with 3 K span are 10.95 and 10.93 J kg−1 K−1 for Gd11Co4In9, 4.66 and 4.64 J kg−1 K−1 for Dy11Co4In9, and 12.29 and 12.09 J kg−1 K−1 for Ho11Co4In9, respectively. The corresponding values of relative cooling power (RCP) and refrigerant capacity (RC) are 538.1 and 405.9 J kg−1 for Gd11Co4In9, 213.9 and 165.9 J kg−1 for Dy11Co4In9, and 475.2 and 357.4 J kg−1 for Ho11Co4In9, respectively. [ABSTRACT FROM AUTHOR]

The crystal structures, magnetic properties and magneto-caloric effects (MCEs) of RE2Ni2In (RE = Pr, Nd, Dy and Ho) compounds were investigated. The results indicate that Pr2Ni2In and Nd2Ni2In compounds have a tetragonal Mo2FeB2-type structure belonging to the P4/mbm space group and undergo a second-order paramagnetic to ferromagnetic (PM to FM) transition at a Curie temperature (TC) of 7.5 and 10.5 K, respectively, whereas Dy2Ni2In and Ho2Ni2In compounds have an orthorhombic Mn2AlB2-type structure belonging to the space group Cmmm and possess a magnetic transition from PM to antiferromagnetic (AFM) at a Néel temperature TN of 19 and 10.5 K together with a first-order field induced metamagnetic transition, respectively. Moreover, an additional magnetic transition at a lower temperature of around 5.5 K is detected for the Ho2Ni2In compound. A considerable reversible magneto-caloric effect is observed accompanying the magnetic phase transition, and the maximum values of the magnetic entropy change (−ΔS maxM) of the present RE2Ni2In series compounds are determined to be 9.3, 11.5, 6.4 and 11.5 J kg−1 K−1 with a magnetic field change (ΔH) of up to 0–5 T for RE = Pr, Nd, Dy and Ho, respectively. [ABSTRACT FROM AUTHOR]

The crystal structure, magnetic properties and magnetocaloric effect (MCE) in A Gd(MoO 4) 2 compounds with A = Li, Na and K were investigated in detail. The X-ray diffraction (XRD) results suggest that all the A Gd(MoO 4) 2 compounds are single phased. The LiGd(MoO 4) 2 and NaGd(MoO 4) 2 crystallize in the tetragonal structure, whereas the KGd(MoO 4) 2 crystallizes in a triclinic structure. All compounds are composed of numerous irregular small particles and the corresponding constituent elements are distributed uniformly. Additionally, all compounds exhibit pronounced MCE at cryogenic temperatures. The maximum magnetic entropy change − Δ S M max values of the A Gd(MoO 4) 2 series compounds reach 33.6, 36.4 and 32.4 J/kg K @ 2.5 K with the Δ H of 0–7 T for A = Li, Na and K, respectively. [ABSTRACT FROM AUTHOR]

The magnetocaloric effect (MCE) and critical behavior in the RE PtMg (RE = Tb, Dy and Ho) intermetallic compounds around Curie temperatures T C were investigated by magnetization measurements. All the RE PtMg compounds exhibit pronounced MCE performance with the maximum magnetic entropy change (− Δ S M max ) values up to 5.1, 7.2, 10.2 J/kg K under the magnetic field change (Δ H) of 0–5 T around T C of 58, 29, and 20 K for RE = Tb, Dy and Ho, respectively. The reasonable and accurate critical exponents for the present RE PtMg series compounds for RE = Tb, Dy and Ho obtained by the Δ H dependence of Δ S M method are evaluated to be β = 0.4691, 0.4681, 0.4141, γ = 1.0412, 1.0482, 1.1067 and δ = 3.2196, 3.2393, 3.6728 around T C , which are verified by the Widom scaling law and scaling equations, respectively. • The magnetocaloric property in RE PtMg (RE = Tb, Dy and Ho) was studied. • A considerable reversible MCE was observed for all compounds. • The critical behavior in RE PtMg (RE = Tb, Dy and Ho) were studied. • The obtained critical exponents obey the Mean-field model. [ABSTRACT FROM AUTHOR]

The structure, magnetic phase transition and magnetocaloric properties of ternary intermetallic RE 5 Ni 2 In 4 ( RE  = Dy, Ho and Er) compounds are investigated. The results of XRD and Rietveld refinement confirm that all the samples crystallized in the orthorhombic Lu 5 Ni 2 In 4 -type structure belonging to the space group of Pbam . The RE 5 Ni 2 In 4 compounds show various magnetic phase transition behaviors, i.e. a ferromagnetic to paramagnetic (FM-PM) phase transition at T C  = 105 K together with an antiferromagnetic to ferromagnetic (AFM-FM) at low temperature T N  = 20 K for the Dy 5 Ni 2 In 4 , the Ho 5 Ni 2 In 4 reveals two different kinds of phase transitions at T N  = 31 K and T C  = 19 K which are corresponding to the second order PM-AFM and the first order AFM-FM phase transitions, and a PM-FM phase transition exists in the Er 5 Ni 2 In 4 at T C  = 21 K. In addition, a large hysteresis loop with particular shape and a high coercive field ( H C  = 4 T) are observed at 3 K for the Dy 5 Ni 2 In 4 compound. The corresponding isothermal magnetization curves change into the state of reversibility when the temperature is 60 K, and the coercivity is reduced to zero. The maximum values of − Δ S M max are determined to be 4.7, 10.1 and 10.2 J/kg K around T C for the RE 5 Ni 2 In 4 ( RE  = Dy, Ho and Er) compounds in a field of 7 T, respectively. [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]

Magnetic cooling (MC) by utilizing the magnetocaloric effect (MCE) has been considered as one of the most potential promising solid state alternative method to present well-used state-of-the-art gas compression cooling technique. In this work, the rare earth (RE)-rich indides Gd 6 Co 2.2 In 0.8 , Tb 6 Co 2.2 In 0.8 , Dy 6 Co 2.2 In 0.8 and Ho 6 Co 2.2 In 0.8 were fabricated and checked with respect to their crystal structure, magnetic properties and magnetocaloric performances. All the RE 6 Co 2.2 In 0.8 samples are crystallized with the orthorhombic Ho 6 Co 2 Ga-type structure and ordered magnetically. Considerable cryogenic magnetocaloric performances have been found. Around the magnetic transition temperatures of 76, 32, 50 and 18 K for Gd 6 Co 2.2 In 0.8 , Tb 6 Co 2.2 In 0.8 , Dy 6 Co 2.2 In 0.8 and Ho 6 Co 2.2 In 0.8 , the magnetic entropy change (Δ S M) peak values with a magnetic change (Δ H) equals to 0–70 kOe and the corresponding temperature averaged Δ S M (with 3 K-lift) are 11.84 and 11.82 J/kg-K, 8.96 and 8.80 J/kg-K, 9.59 and 9.54 J/kg-K, 20.83 and 20.38 J/kg-K for Gd 6 Co 2.2 In 0.8 , Tb 6 Co 2.2 In 0.8 , Dy 6 Co 2.2 In 0.8 and Ho 6 Co 2.2 In 0.8 , respectively. • The RE 6 Co 2.2 In 0.8 (RE = Gd, Tb, Dy, Ho) compounds are fabricated. • Magnetic properties and MCE in RE 6 Co 2.2 In 0.8 compounds were studied. • Considerable MCE parameters were observed at low temperature. [ABSTRACT FROM AUTHOR]

The layer-like RE 11 Ni 4 In 9 (RE = Gd, Dy and Ho) intermetallic compounds were successfully fabricated and systematically investigated concerning crystal structure, magnetic phase transitions and magnetocaloric effect (MCE). The RE 11 Ni 4 In 9 compounds crystallize in layer-like orthorhombic crystal structure (Cmmm space group) which is composed of CsCl-type and AlB 2 -type units with the ratio of 9 : 2. The RE 11 Ni 4 In 9 compounds present multiple magnetic phase transitions at low temperature. Except for the phase transition at low temperature region, the major phase transitions of the present series compounds are of second-ordered phase transitions (SOPTs). Around the magnetic phase transition temperatures at 91, 18 and 13.5 K for Gd 11 Ni 4 In 9 , Dy 11 Ni 4 In 9 and Ho 11 Ni 4 In 9 compounds, the values of peak magnetic entropy change (− Δ S M max) with magnetic flux density change Δ H = 0–7 T and the temperature averaged magnetic entropy change with 3 K lift are 3.58 and 3.55 J/kg-K, 6.02 and 5.94 J/kg-K, as well as 12.44 and 12.25 J/kg-K for Gd 11 Ni 4 In 9 , Dy 11 Ni 4 In 9 and Ho 11 Ni 4 In 9 compounds, respectively. The corresponding relative cooling power (refrigerant capacity) values are 269.0 (206.4), 194.9 (144.7), and 353.0 (269.2) J/kg, respectively. • The RE 11 Ni 4 In 9 (RE = Gd, Dy and Ho) intermetallic compounds are fabricated. • Magnetic properties and MCE in RE 11 Ni 4 In 9 amorphous ribbon were studied. • Considerable MCE parameters were observed at low temperature. [ABSTRACT FROM AUTHOR]

The europium-based intermetallic compounds EuAgZn, EuAgCd, EuPtZn and EuAuCd were synthesized and their magnetic properties and magnetocaloric performances were systematically studied. EuAgZn and EuAgCd compounds crystallize in a KHg 2 -type structure belonging to space group Imma , whereas EuPtZn and EuAuCd crystallize in a TiNiSi-type structure belonging to space group Pnma. The four compounds contain stable divalent europium and order ferromagnetically with Curie temperatures of T C ~29, 27, 20 and 22 K for EuAgZn, EuAgCd, EuPtZn and EuAuCd, respectively. A considerable tunable reversible MCE can be observed accompanied by a second-order magnetic transition. For the field change of 0–2 and 0–5 T, the − Δ S Μ max values are evaluated to be 7.7, 7.2, 8.2, 8.0 and 14.9, 13.5, 15.3, 13.7 J/kgK for EuAgZn, EuAgCd, EuPtZn and EuAuCd, respectively. • Four Eu-based equiatomic intermetallic compounds were synthesized. • Magnetism and MCE in EuAgZn, EuAgCd, EuPtZn and EuAuCd were studied. • All the compounds exhibit large MCE at low temperature. [ABSTRACT FROM AUTHOR]

Abstract Polycrystalline double perovskite Y 2 CoMnO 6 oxides ceramics sintered at four different temperatures from 1000 °C to 1300 °C have been fabricated by conventional sol-gel method. All the Y 2 CoMnO 6 compounds are single phase with monoclinic structure (P 21 /n space group). The mean grain size grows significantly large and the shape becomes regular obviously with increasing sintering temperature. The effect of sintering temperature on magnetic properties of Y 2 CoMnO 6 compounds has been studied in detail. We found that the oxygen vacancies are introduced by sintering at high temperature has a certain influence on the magnetic properties. Moreover, the magnetic entropy changes (-∆ S M) as well as relative cooling power (RCP) in the double perovskite Y 2 CoMnO 6 oxides ceramics around paramagnetic to ferromagnetic transition were also investigated. [ABSTRACT FROM AUTHOR]

Nowadays, the rare earths (RE) based magnetic materials with various promising functional characterizations are playing particularly important roles in present modern society and daily life. The magnetocaloric (MC) effect which is the basis of solid state magnetic refrigeration (MR) technology has been extensively investigated in various magnetic materials. In this work, a series of high quality RE -based RE 2 BaZnO 5 (RE = Gd, Dy, Ho, and Er) compounds have been fabricated and a combination of theoretical and experimental investigation has been performed in terms of the crystal structure, electronic structure, magnetic properties and magnetic phase transition (MPT) as well as the MC effects and MC performance. All the RE 2 BaZnO 5 compounds are confirmed to crystallize in the orthorhombic structure belonging to Pnma space group and with a typical semi-conductor characteristic. Based on the magnetization measurements and the first principle calculations, all the RE 2 BaZnO 5 compounds are ordering magnetically below 3 K and the ground state is of a ferromagnetic (FM) ordering for RE = Dy or Ho, whereas is of an antiferromagnetic (AFM) ordering for RE = Gd or Er, respectively. Additionally, considerable MC effects have been observed for all the RE 2 BaZnO 5 compounds which are related to the first ordered MPT for RE = Gd or Er, whereas related to the second order MPT for RE = Dy or Ho, respectively. Moreover, considerable MC effects and promising MC performance have been realized in the present RE 2 BaZnO 5 compounds, especially for the Dy 2 BaZnO 5 and Ho 2 BaZnO 5 , making them considerable for cryogenic MR applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The rare-earths (RE) based materials with large magnetocaloric effect (MCE) have been recently recognized as potential candidates for practical solid-state magnetic refrigeration. In this work, the two light RE -based ternary RE Cu 2 Si 2 (RE = Nd and Pr) compounds were fabricated by arc-melting method and investigated the structural, magnetic and magnetocaloric properties. Both RE Cu 2 Si 2 compounds are found to crystallize in a ThCr 2 Si 2 -type layered crystal structure with the I 4/ mmm space group and undergo a field-induced first-ordered magnetic transition (MT) around 13.6 and 3.5 K for NdCu 2 Si 2 and PrCu 2 Si 2 , respectively. Large reversible MCE has been observed in both RE Cu 2 Si 2 compounds, and the magnetocaloric parameters of the maximum isothermal magnetic entropy change (-Δ S M max) and relative cooling power (RCP) with the magnetic field change (Δ H) of 0–7 T are determined to be 5.9 J/kg-K and 82.6 J/kg for NdCu 2 Si 2 compound and to be 8.0 J/kg-K and 67.2 J/kg for PrCu 2 Si 2 compound, respectively. • The ternary RE Cu 2 Si 2 (RE = Nd and Pr) compounds are synthesized. • Cryogenic magnetic properties in RE Cu 2 Si 2 were studied. • The magnetocaloric parameters in RE Cu 2 Si 2 compounds were determined. [ABSTRACT FROM AUTHOR]

The magnetic refrigeration (MR) technology by utilizing the magnetocaloric (MC) effects of magnetic solids have been realized to be a promising energy efficiency and environmentally friendly technology. Developing or discovering proper magnetic solids with promising MC performances is one of the most important tasks at present stage since a huge gap still exists between the requirement of practical MR application and the MC performances of the magnetic solids. Herein, we reported a combined theoretical and experimental investigation of the crystal structure together with the magnetic properties, magnetic phase transition (MPT) and MC performances in Gd 2 MgTiO 6 oxide. The Gd 2 MgTiO 6 is confirmed to crystalize in a B -site ordered monoclinic double perovskite (DP) crystal structure. A rather unstable antiferromagnetic (AFM) interaction with large magnetic moment and semi-conductor characteristic with the band gap of 2.977 eV have been confirmed in Gd 2 TiMgO 6 DP oxide at ground state. Giant reversible cryogenic MC effect together with excellent MC performances have been confirmed by a series of the figure of merits including the values of maximum magnetic entropy change (-Δ S M) and refrigerant capacity (RC), which are evaluated to be 46.21 J/kgK and 300.27 J/kg around 3.3 K with the magnetic change of 0–7 T, these values are much better than most of the recently reported famous cryogenic MC materials and the commercialized magnetic refrigerants gadolinium gallium garnet (GGG) as well. The observed excellent MC performances suggest that Gd 2 TiMgO 6 DP oxide is a promising candidate material for cryogenic MR applications. Graphical abstract [Display omitted]. [ABSTRACT FROM AUTHOR]

Magnetocaloric effect (MCE) is a thermodynamic response of the coupling effect between the magnetic sub-lattice(s) with applied magnetic fields, which is strongly correlated with the corresponding magnetic transition. In this work, the magnetic properties, magnetic phase transition, MCE and critical behavior of the paramagnetic (PM) to ferromagnetic (FM) transition in double perovskite RE 2 CrMnO 6 (RE = La, Pr, and Nd) compounds are investigated. The double perovskite compounds reveal a second-ordered magnetic phase transition around T C of 112, 93, and 80 K for RE of La, Pr, and Nd, respectively. The corresponding values of peak magnetic entropy change (- ΔS M max) around T C are 1.31, 1.86, and 2.23 J kg−1K−1 under the ΔH of 0–7 T. Moreover, the critical exponent study was conducted to probe the nature of critical behavior around the PM to FM transition by the modified Arrott plot (MAP), Kouvel-Fisher (K–F), ΔH dependence of - ΔS M max, and universal scaling hypothesis methods. The evaluated reliable critical exponents (β, γ, and δ) data for RE 2 CrMnO 6 (RE = La, Pr, and Nd) follows the mean-field theory model, proving the existence of long-range FM orders in these double-perovskite oxide compounds. [ABSTRACT FROM AUTHOR]

• The quaternary RE Cr 2 Si 2 C (RE = Gd, Tb, Dy) compounds are fabricated. • The structural, magnetic, MTP and MC properties in RE Cr 2 Si 2 C were studied. • The GdCr 2 Si 2 C compound is considerable for cryogenic magnetic refrigeration. The rare earths (RE) based materials with large reversible magnetocaloric effects have been recently recognized as good candidates for practical cryogenic magnetic refrigeration. In this work, three RE -based quaternary silicon carbides of RE Cr 2 Si 2 C (RE = Gd, Tb, Dy) were synthesized and determined the crystal structure, magnetic properties, magnetic phase transition, and magnetocaloric performances. All RE Cr 2 Si 2 C compounds are crystallized in the carbon-filled CeMg 2 Si 2 -type crystal structure and revealed a second-order magnetic phase transition from ferromagnetic to paramagnetic without noticeable field or thermal hysteresis around the Curie temperatures (~10.9 K for GdCr 2 Si 2 C, ~16.6 K for TbCr 2 Si 2 C, and ~10.7 K for DyCr 2 Si 2 C). The magnetocaloric parameters including the maximum magnetic entropy change, temperature-averaged entropy changes with 3 K lift, as well as refrigerant capacity/relative cooling power are applied to determine the magnetocaloric performances, and the evaluated values are 21.7, 14.6 and 9.8 J/kgK, 20.97, 14.51, and 9.73 J/kgK, as well as 248.3/328.8, 302.8/393.8, and 211.3/274.9 J/kg for GdCr 2 Si 2 C, TbCr 2 Si 2 C, and DyCr 2 Si 2 C under the field change of 0–50 kOe. These results indicate that the GdCr 2 Si 2 C possesses promising magnetocaloric performances and is considerable for cryogenic magnetic refrigeration application. [ABSTRACT FROM AUTHOR]