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The structure, magnetic transition and magnetocaloric properties in the ternary gallium intermetallic compounds of Ho 2 Ni 2 Ga and Tm 2 Ni 2 Ga have been systematically investigated by using X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and magnetization measurements. As found from powder XRD and Rietveld refinement, Ho 2 Ni 2 Ga and Tm 2 Ni 2 Ga crystallized in an orthorhombic structure of the W 2 B 2 Co type belonging to the Immm space group. Both compounds are ordering antiferromagnetically at low temperatures and under low magnetic fields together with a field-induced metamagnetic transition from antiferromagnetic (AFM) to ferromagnetic (FM). Peculiar and similar magnetocaloric properties are observed for both compounds, i. e., an inverse magnetocaloric effect (positive magnetic entropy change, Δ S M ) under low magnetic field changes (Δ H ) and at low temperatures together with a large normal reversible magnetocaloric effect under high Δ H . The positive Δ S M below/at the Néel temperatures ( T N ) is ascribed to first order transition from antiferromagnetic (AFM) to ferromagnetic (FM) states, whereas the negative Δ S M above T N is due to the fact of the magnetic transition from paramagnetic (PM) to ferromagnetic (FM) states. Based on the field-dependent magnetization data, the maximum magnetic entropy change (−Δ S M max ), relative cooling power ( RCP ) and refrigerant capacity ( RC ) are established, and the corresponding values are 9.6 J/kg K, 276 J/kg and 206 J/kg for Ho 2 Ni 2 Ga, and are 4.3 J/kg K, 60 J/kg and 46 J/kg for Tm 2 Ni 2 Ga, respectively, for a magnetic field change of 0–70 kOe. [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]

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]

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 magnetism and magnetocaloric effect (MCE) were investigated in Er 4 CoCd compound. • A large magnetocaloric effect in Er 4 CoCd compound was observed. • The origin of MCE and its potential application in Er 4 CoCd were discussed. The Er-based compound Er 4 CoCd was synthesized successfully and its structural, magnetic together with magnetocaloric properties were investigated in detail. The Er 4 CoCd crystallized in a Gd 4 RhIn-type structure with the space group of F 4 ¯ 3 m , which was confirmed by Rietveld refinement. A ferromagnetic transition was observed around its Curie temperature (T C) of 12.5 K accompanied by a large magnetocaloric effect (MCE). The performance of MCE for Er 4 CoCd was evaluated by the isothermal maximal magnetic entropy (- Δ S M max) , the temperature averaged entropy change (TEC) at 10 K temperature lift [ TEC (10 K)], and the relative cooling power (RCP). The values of - Δ S M max , TEC (10 K), and RCP of Er 4 CoCd are 20.4 J/kg K, 19.2 J/kg K, and 503 J/kg under the magnetic field change (Δ H) of 0–5 T, respectively. [ABSTRACT FROM AUTHOR]