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In this work, we fabricated a polycrystalline Tb2FeCrO6 double perovskite (DP) oxide by a solid-state reaction method and determined its structural, magnetic, and magnetocaloric (MC) properties. The Tb2FeCrO6 DP oxide was found to crystallize in a DP-type structure with the Pbnm space group and to undergo a paramagnetic-to-antiferromagnetic transition at a temperature of ~ 8.5 K. A large low-temperature MC effect was observed in the Tb2FeCrO6 DP oxide. The MC parameters in terms of maximum magnetic entropy changes, temperature-averaged entropy change (5 K), and relative cooling power for Tb2FeCrO6 DP oxide under a magnetic field change of 0–7 T were 12.9 J/kg K, 12.7 J/kg K, and 341.4 J/kg, respectively. These parameters were consistent with similarly high levels in recently updated MC materials, making the material a suitable candidate for low-temperature magnetic cooling applications. [ABSTRACT FROM AUTHOR]

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]

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]

The magnetocaloric effect has been extensively investigated in various types of magnetic solids to not only develop practical magnetic cooling applications but also deepen the understanding of these materials' underlying inherent properties. Through experimental determination and theoretical calculation, we conducted a systematic investigation of Gd 4 Ga 2 O 9 oxide in terms of its structural, magnetic, and magnetocaloric properties and found it to crystallize in a monoclinic structure belonging to the space group P 2 1 / c and to possess an antiferromagnetic semiconducting ground state. The consistent elements were uniformly distributed up to the nanoscale and presented as Gd3+, Ga3+, and O 2 states, respectively. The magnetocaloric performances of Gd 4 Ga 2 O 9 oxide were checked according to the parameters of maximum magnetic entropy change, refrigerant capacity, and temperature-averaged entropy changes (lift of 5 K), which were determined to be 25.77 J/kgK, 218.27 J/kg, and 23.43 J/kgK under 0–7 T magnetic field change. These parameters of Gd 4 Ga 2 O 9 oxide are comparable to those of some recently reported materials with prominent performances, which means that it can be considered for cryogenic magnetic cooling applications. [ABSTRACT FROM AUTHOR]

We herein provided a systematical determination of the structural and magnetic properties, especially of the magnetocaloric effect (MCE) and magnetocaloric performances of four rare-earth oxychlorides, i. e., the RE OCl (RE = Ho, Dy, Tb and Gd) compounds. The studied RE OCl compounds are all crystallized in the tetragonal matlockite structure (P 4/ nmm space group) and the RE , O, and Cl elements are with the RE 3+, O2−, and Cl− valence states, respectively. The DyOCl, TbOCl and GdOCl compounds reveal an antiferromagnetic transition at around approximate 9.5, 3.7 and 4.8 K, respectively. The magnetocaloric performances are checked by the maximum magnetic entropy change, relative cooling power, and temperature-averaged entropy change with 5 K lift, which are found to be 14.16 J/kgK, 375.55 J/kg and 13.89 J/kgK for HoOCl, to be 14.88 J/kgK, 488.14 J/kg, and 14.60 J/kgK for DyOCl, to be 14.59 J/kgK, 419.67 J/kg, and 14.42 J/kgK for TbOCl, and to be 16.16 J/kgK, 213.68 J/kg, and 14.39 J/kgK for GdOCl, with the magnetic field change of 0–7 T, respectively. [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]

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]