ngwei Li

Reversible table-like magnetocaloric effect in Eu4PdMg over a very large temperature span

The magnetic properties and magnetocaloric effect (MCE) of the ternary intermetallic compound of Eu4PdMg have been investigated. Eu4PdMg has a very magnetic field sensitive magnetic phase transition, resulting in a reversible, table-like MCE over a broad temperature range. For the magnetic field changes of 0–5u2009T and 0–7u2009T, the maximum values of magnetic entropy change (−ΔSMmax) are 5.5u2009J kg−1 K−1 and 7.2u2009J kg−1 K−1, respectively, the corresponding refrigeration capacity (RC) are 977u2009J kg−1 and 1346u2009J kg−1. The RC values are obviously larger than those of some potential magnetic refrigerant materials at similar temperature region, making Eu4PdMg attractive for magnetic refrigeration.

Giant low field magnetocaloric effect and field-induced metamagnetic transition in TmZn

The magnetic properties and the magnetocaloric effect (MCE) in TmZn have been studied by magnetization and heat capacity measurements. The TmZn compound exhibits a ferromagnetic state below a Curie temperature of TCu2009=u20098.4u2009K and processes a field-induced metamagnetic phase transition around and above TC. A giant reversible MCE was observed in TmZn. For a field change of 0–5u2009T, the maximum values of magnetic entropy change (−ΔSMmax) and adiabatic temperature change (ΔTadmax) are 26.9u2009J/kg K and 8.6u2009K, the corresponding values of relative cooling power and refrigerant capacity are 269 and 214u2009J/kg, respectively. Particularly, the values of −ΔSMmax reach 11.8 and 19.6u2009J/kg K for a low field change of 0–1 and 0–2u2009T, respectively. The present results indicate that TmZn could be a promising candidate for low temperature and low field magnetic refrigeration.

Magnetic properties and large magnetocaloric effect in Ho2Cu2In and Ho2Au2In compounds

The magnetic and magnetocaloric properties of Ho2Cu2In and Ho2Au2In have been investigated. A second-order magnetic phase transition from a paramagnetic to a ferromagnetic state was observed for Ho2Cu2In and Ho2Au2In at Curie temperatures of TCxa0~xa030 and 21xa0K, respectively. An additional magnetic transition at 8xa0K was also observed for Ho2Au2In which is probably related to a spin reorientation phenomenon. A large reversible magnetocaloric effect was observed for both compounds. The maximum values of magnetic entropy change (−ΔSMmax) are 21.9 and 15.8xa0J/kgxa0K under a field change of 0–7 T for Ho2Cu2In and Ho2Au2In, with the values of the relative cooling power of 638 and 490xa0J/kg, respectively.

Achievement of a table-like magnetocaloric effect in the dual-phase ErZn2/ErZn composite

ABSTRACT Dual-phase ErZn2/ErZn composite was obtained by induction-melting method. The composite crystallizes in the phases of ErZn2 and ErZn with the weight ratio of 53.8:46.2. The composite undergoes two successive magnetic phase transitions. And accordingly two peaks (partly overlapped) are appeared in the temperature dependence of magnetic part of entropy change ΔSM(T) curves which resulting in a table-like magnetocaloric effect (MCE) and large refrigerant capacity (RC). The MCE parameters are comparable or even larger than most of the recently reported potential magnetic refrigerant materials at similar temperature region, making the dual-phase ErZn2/ErZn composite attractive for low-temperature magnetic refrigeration. GRAPHICAL ABSTRACT IMPACT STATEMENT Table-like magnetocaloric effect (MCE) was realized in dual-phase ErZn2/ErZn composite, the MCE parameters are comparable or even larger than most of the reported materials, making ErZn2/ErZn composite attractive for magnetic refrigeration.

Large refrigerant capacity induced by table-like magnetocaloric effect in amorphous Er0.2Gd0.2Ho0.2Co0.2Cu0.2 ribbons

ABSTRACT The microstructure, magnetism, and magnetocaloric properties in melt-spun Er0.2Gd0.2Ho0.2Co0.2Cu0.2 ribbons were reported. The ribbons are fully amorphousized and all the constituent elements are distributed uniformly. The large table-like magnetocaloric effect (MCE) from 25 to 75u2009K has been observed, resulting in a large value of refrigerant capacity (RC). With the magnetic field change (Δµ0H) of 0–5u2009T, the values of maximum magnetic entropy change reaches 11.1u2009J/kgu2009K, and the corresponding value of RC are as large as 806u2009J/kg, make the amorphous Er0.2Gd0.2Ho0.2Co0.2Cu0.2 ribbons extremely attractive for cryogenic magnetic refrigeration. GRAPHICAL ABSTRACT IMPACT STATEMENT Table-like magnetocaloric effect (MCE) was observed in amorphous Er0.2Gd0.2Ho0.2Co0.2Cu0.2 ribbon, the MCE parameters are comparable or obviously larger than most of reported materials, making it attractive for magnetic refrigeration.

Magnetic properties and giant reversible magnetocaloric effect in GdCoC2

The crystal structure, magnetic properties and magnetocaloric effect (MCE) of GdCoC2 have been studied. The compound crystallizes in an orthorhombic CeNiC2-type structure which belongs to the Amm2 space group. A giant reversible MCE is observed in GdCoC2 accompanied by a second-order paramagnetic to ferromagnetic (PM–FM) phase transition around the Curie temperature ∼15 K. For the magnetic field change of 0–5 T, the maximum values of the magnetic entropy change (−ΔSmaxM), relative cooling power (RCP), and refrigerant capacity (RC) are 28.4 J kg−1 K−1, 566 J kg−1 and 369 J kg−1, respectively. The present results indicate that GdCoC2 is a promising candidate for low temperature magnetic refrigeration.

Magnetism and Magnetocaloric Effect in EuAuZn

The magnetic properties and magnetocaloric effect (MCE) in the ternary intermetallic compound EuAuZn have been studied via magnetization and heat capacity measurements. The compound orders ferromagnetically below T_C ~ 52 K with a spin reorientation transition at T_SR ~ 19 K. A large reversible MCE has been observed in EuAuZn accompanied by a second-order magnetic phase transition from a paramagnetic to a ferromagnetic state. Under a field change of 5 T, the maximum values of magnetic entropy change (-ΔS_M^max) and adiabatic temperature change (ΔT_ad^max) are 9.1 J/kg·K and 3.8 K, respectively, the corresponding relative cooling power is 318 J/kg.

Observation of large magnetocaloric effect in equiatomic binary compound ErZn

The magnetism, magnetocaloric effect and universal behaviour in rare earth Zinc binary compound of ErZn have been studied. The ErZn compound undergoes a second order paramagnetic (PM) to ferromagnetic (FM) transition at Curie temperature of TC ∼ 20 K. The ErZn compound exhibits a large reversible magnetocaloric effect (MCE) around its own TC. The rescaled magnetic entropy change curves overlap with each other under various magnetic field changes, further confirming the ErZn with the second order phase transition. For the magnetic field change of 0-7 T, the maximum values of the magnetic entropy change (−ΔSMmax), relative cooling power (RCP) and refrigerant capacity (RC) for ErZn are 23.3 J/kg K, 581 J/kg and 437 J/kg, respectively.

Significant high-frequency electromagnetic wave absorption performance of Ni 2+ x Mn 1− x Ga alloys

The electromagnetic wave (EMW) absorption properties in Heusler-type ferromagnetic Ni2+xMn1−xGa alloys were systematically investigated. Significant electromagnetic absorption performance at 2.0–18.0xa0GHz was observed for Ni2+xMn1−xGa alloys. The values of the complex permittivity (εr) and permeability (μr), as well as the reflection loss (RL), peak frequency (fm) and bandwidth (Δf) of Ni2+xMn1−xGa can be effectively tuned by the alloy component (Ni/Mn ratio). The magnetic loss factor (tan δμ) shows pronounced multi-resonance behavior, and dielectric loss factor (tan δε) has dramatic dielectric relaxation. The RL exceeding −u200910xa0dB corresponding to 90% absorption of incident microwave can be achieved for the Ni2MnGa in a broad frequency range of 6.3–18.0xa0GHz together with the thickness from 1.66 to 4.75xa0mm. Particularly, the maximum RL reaches −u200949.1xa0dB at 13.3xa0GHz with the thickness of 2.57xa0mm for Ni2MnGa. The present results indicated that the ferromagnetic Ni2+xMn1−xGa alloys could be attractive candidates for broadband and high-frequency EMW absorption.

Magnetism and large magnetocaloric effect in Er 4 PdMg compound

The magnetic properties and the magnetocaloric effect (MCE) of Er4PdMg compound have been investigated by magnetization and heat capacity measurements. The compound undergoes a second order magnetic phase transition from a paramagnetic to a ferromagnetic state at Curie temperatures of TC ~ 16 K. For a field change of 0-7 T, the maximum values of magnetic entropy change (-ΔSMmax) and adiabatic temperature change are 20.6 J/ kg K and 5.5 K, respectively. The corresponding relative cooling power (RCP) was evaluated to be 716 J/kg.