1. Metamagnetic transition and magnetocaloric properties in antiferromagnetic Ho2Ni2Ga and Tm2Ni2Ga compounds.
- Author
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Zhang, Yikun, Yang, Yang, Hou, Chunjuan, Guo, Dan, Li, Xi, Ren, Zhongming, and Wilde, Gerhard
- Subjects
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METAMAGNETISM , *MAGNETOCALORIC effects , *INTERMETALLIC compounds , *GALLIUM compounds , *X-ray diffraction , *SCANNING electron microscopes , *SPACE groups - Abstract
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]
- Published
- 2018
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