Abstract
The magnetic properties and magnetocaloric effect (MCE) of Gd4Sb3-xRx (R = Si, Ge, Sn, x = 0, 0.25, 0.5, 0.75) compounds have been studied systematically. The Curie temperature (Tc) of these compounds can be tuned from 270 K to 305 K depending on the substitution amount. All the compounds undergo a second-order magnetic transition from ferromagnetic (FM) state to paramagnetic (PM) state and exhibit considerable reversible MCE near room temperature. The maximum of magnetic entropy change (ΔSMmax) for a magnetic field change of 7 T can reach 4.25 Jkg-1K-1 in Gd4Sb3 phase and independent on Si substitution amount. By Ge and Sn substitution, reduced ΔSMmax of 3.5 and 4.25 Jkg-1K-1 can be obtained in Gd4Sb2.75Ge0.25 and Gd4Sb2.75Sn0.25 alloys respectively. The considerable MCE with no hysteresis and working temperature near room temperature suggests that these materials could be promising candidates as ambient magnetocaloric materials.
Highlights
Magnetic refrigerant techniques based on the magnetocaloric effect (MCE) have attracted considerable attentions for their promising advantages, like higher efficiency, environmental friendliness and high reliability compared with refrigeration techniques based on gas compression cycles
Large MCE materials with second order magnetic transitions usually have a reversible behavior as a function of the temperature and the magnetic field, which is beneficial for applications
In order to make the materials to realize the ambient magnetic refrigeration capability, using the Si, Ge, Sn substitution for Sb to tune the phase transition temperature is conducted in present work
Summary
Magnetic refrigerant techniques based on the magnetocaloric effect (MCE) have attracted considerable attentions for their promising advantages, like higher efficiency, environmental friendliness and high reliability compared with refrigeration techniques based on gas compression cycles. For the past decades, most researches on MCE have been focused on the materials with the firstorder magnetic phase transition. Many materials that undergo a first-order phase transition at room temperature possesses large magnetocaloric effects, such as Gd5Ge2Si2,3 MnFeP0.45As0.55,5 La(Fe1-xSix)13.6 These materials have been considered to be the most promising systems to achieve magnetic refrigeration at room temperature.. Gd, many Gdbased intermetallic compounds exhibit large MCE, such as GdCo-Dy, Gd-Co-Mn, Gd-Co-Si, Gd-Fe-Al, Gd-Co, etc The emergence of these materials successfully solves the problems of high price of pure Gd, unstable chemical properties, single Curie temperature, and too large working magnetic field. These materials have some obvious disadvantages like complex preparation process and strict annealing process. Phase formation, the magnetic properties and the related magnetocaloric effects are are investigated systematically
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