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Magnetic refrigeration (MR) based on the magnetocaloric effect (MCE) has been recognized as an environmentally benign and energy-efficient cooling technology. Exploring suitable magnetocaloric materials is a crucial prerequisite for practical MR applications. We have herein provided a systematic investigation of the crystal structure, microstructure, electronic structure, magnetic phase transition, critical behavior, and MCE of the GdCoC compound featuring excellent cryogenic magnetocaloric performance by means of experimental determination and theoretical calculation. The GdCoC compound is crystallized in a simple layered tetragonal crystal structure with a P 4 2 / mmc space group and undergoes two successive ferromagnetic (FM) transitions along with a low-temperature weak antiferromagnetic (AFM) transition under low magnetic fields. Density functional theory calculations confirms the FM coupling of the Gd and Co intra-sublattice interactions, whereas AFM coupling for their inter-sublattice interaction. The magnetic transitions are merged in to one under high magnetic fields which has been confirmed to be second-order type and its critical behavior can be understood in the framework of tri-critical mean-field model, whereas the low-temperature weak AFM transition is belonging to the first-order type. The excellent magnetocaloric performance of the GdCoC compound was identified by the parameters of magnetic entropy change, adiabatic temperature change, temperature-averaged entropy change, relative cooling power, and refrigerant capacity, which are superior to most of the well-known magnetocaloric materials with similar working temperatures, making it attractive for practical cryogenic MR applications. [Display omitted] [ABSTRACT FROM AUTHOR]

The magnetocaloric effect (MCE) has been extensively studied in various magnetic solids, aiming to both facilitate practical applications in magnetic cooling and deepen our understanding these materials' intrinsic properties. This study presents a systematic investigation of Gd 2 Ti 2 O 7 oxide, characterized by a geometrically frustrated magnetic structure, focusing on its structural and magnetic characteristics through experimental analysis and theoretical calculations. Emphasis is placed on its magnetic phase transition (MPT) and magnetocaloric properties, scrutinizing temperatures as low as 0.4 K and magnetic fields up to 16 T. The results reveal that Gd 2 Ti 2 O 7 oxide possesses a crystalline cubic pyrochlore-type structure with an antiferromagnetic (AFM) semiconductor ground state. The material undergoes a first-order MPT in low field and low-temperature regimes, transitioning to a second-order MPT above 2 K up to 16 T. Evaluation of magnetocaloric parameters, including maximum magnetic entropy change, temperature-averaged entropy change, relative cooling power, and refrigerant capacity, indicates moderate values under low magnetic field changes, while significantly large values are achievable under high magnetic field changes. This finding suggests that potential cryogenic magnetocaloric materials (MCMs) with optimal performance should exhibit low MPT temperatures induced by magnetic frustration and possess a ground state with a sufficiently large magnetic moment induced by low magnetic fields, thus avoiding excessively strong AFM coupling. This study lays the groundwork for future cryogenic MCM design and provides valuable insights into the intrinsic properties of geometrically frustrated magnetic materials. [Display omitted] [ABSTRACT FROM AUTHOR]

In this work, we fabricated the RE 2 O 2 SO 4 (RE = Gd, Tb, Dy and Ho) oxides by thermal decomposition and systematically determined regarding their structural and magnetic properties, especially of the magnetic phase transition (MPT) and magnetocaloric effect (MCE). All of these RE 2 O 2 SO 4 oxides are confirmed to crystallize in an orthogonal structure (space group: pmnb); the constituting elements are all distributed uniformly and presented as the RE 3+, S6+, and O2− valence states, respectively. They all exhibit a typical cryogenic MPT from paramagnetic to antiferromagnetic (AFM) state together with a field-induced metamagnetic transition (first-order type MPT) from AFM to ferromagnetic state below their MPT temperatures. All of these RE 2 O 2 SO 4 oxides exhibit considerable direct and inverse cryogenic MCE. The determined direct magnetocaloric parameters of present RE 2 O 2 SO 4 oxides, especially of Gd 2 O 2 SO 4 and Ho 2 O 2 SO 4 oxides, are comparable with most of recently reported RE -based magnetic solids, making them also considerable for practical cryogenic MR applications. [ABSTRACT FROM AUTHOR]

We herein investigated four rare earth (RE)-based oxides, the RE 2 SiO 5 (RE = Gd, Dy, Ho, and Er) silicates, regarding their structural and cryogenic magnetic properties. All the RE 2 SiO 5 silicates are found to crystallized in a monoclinic structure. X-ray photoemission spectroscopy spectra illustrate that RE , Si and O elements in RE 2 SiO 5 silicates are present as RE 3+, Si4+, and O2−, respectively. The Dy 2 SiO 5 reveals a first-order magnetic transition around 4.5 K. The magnetic phase transition temperatures are probably below 2 K for the RE 2 SiO 5 (RE = Gd, Ho, and Er) silicates. Large cryogenic magnetocaloric effects (MCE) and good magnetocaloric performances were observed in the RE 2 SiO 5 silicates. The MCE parameters in terms of the maximum magnetic entropy changes, the temperature-averaged entropy change (5 K-lift) and refrigerant capacity under a magnetic field change of 0–5 T are determined to be 35.5, 30.4 J/kgK, and 215.7 J/kg for Gd 2 SiO 5 , to be 13.3, 12.9 J/kgK, and 190.5 J/kg for Dy 2 SiO 5 , to be 15.3, 15.1 J/kgK, and 274.1 J/kg for Ho 2 SiO 5 and to be 17.9, 16.5 J/kgK, and 181.14 J/kg for Er 2 SiO 5 , respectively. These derived values of MCE parameters of the RE 2 SiO 5 silicates, especially for Gd 2 SiO 5 , are at similarly high level with or better than those of the updated candidate materials, making them also of potential for practical magnetic refrigeration applications. [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]

We fabricated the amorphous Ho 0.2 Tm 0.2 Gd 0.2 Co 0.2 Al 0.2 ribbon by melt-spun method and systematically investigated its glass forming ability (GFA) and magnetic properties, especially of the magnetic phase transition (MPT) and magneto-caloric (MC) effect. The melt-spun Ho 0.2 Tm 0.2 Gd 0.2 Co 0.2 Al 0.2 ribbon is found to exhibit a fully amorphous structure and good GFA. The amorphous Ho 0.2 Tm 0.2 Gd 0.2 Co 0.2 Al 0.2 ribbon undergoes a second order type MPT around 32.6 K from ferromagnetic to paramagnetic state. Large reversible low temperature MC effect and good MC performances in the amorphous Ho 0.2 Tm 0.2 Gd 0.2 Co 0.2 Al 0.2 ribbon were realized which was identified by the parameters of magnetic entropy change, temperature-averaged entropy change, and refrigerant capacity. These parameters are are at similarly high level with recently reported low temperature MC materials, making the amorphous Ho 0.2 Tm 0.2 Gd 0.2 Co 0.2 Al 0.2 ribbon also attractive for magnetic cooling. [ABSTRACT FROM AUTHOR]