Application of Large Magnetocaloric Effects in Itinerant-Electron Metamagnets to Cooling Systems

2006 ◽  
Vol 512 ◽  
pp. 137-144 ◽  
Author(s):  
Kazuaki Fukamichi ◽  
A. Fujita ◽  
S. Fujieda
Keyword(s):  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Partial Substitution ◽  
Itinerant Electron ◽  
Cooling Systems ◽  
Wide Range ◽  
Magnetic Field Change ◽  
The Magnetic Field ◽  
Curie Temperature Tc

The La(FexSi1-x)13 compounds exhibit large magnetocaloric effects (MCEs) due to the itinerant-electron metamagnetic (IEM) transition. By hydrogen absorption, the Curie temperature TC increases up to room temperature with retaining the IEM transition. The La(Fe0.90Si0.10)13H1.1 compound indicates a large isothermal magnetic entropy change of ∆Sm = - 28 J/kg K at 287 K in the magnetic field change from 0 to 2 T (∆B = 2 T). In addition, the MCEs are enhanced by partial substitution of Ce for La. The value of TC for La(FexSi1-x)13 is decreased by partial substitution of Mn for Fe, keeping excellent MCEs. Consequently, the La(FexSi1-x)13 and their modified compounds are promising as magnetic refrigerants working at a wide range of temperature covering room temperature.

Large Isothermal Magnetic Entropy Change after Hydrogen Absorption into La0.5Pr0.5(Fe0.88Si0.12)13

2007 ◽  
Vol 26-28 ◽  
pp. 577-580
Author(s):  
S. Fujieda ◽  
A. Fujita ◽  
Kazuaki Fukamichi
Keyword(s):  
Hydrogen Absorption ◽  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Partial Substitution ◽  
Magnetic Entropy ◽  
Field Change ◽  
Maximum Value ◽  
Magnetic Field Change ◽  
Curie Temperature Tc

The influences of hydrogen absorption on the Curie temperature TC and the isothermal magnetic entropy change for La0.5Pr0.5(Fe0.88Si0.12)13 have been investigated, because the magnetocaloric effects have been confirmed to be enhanced after a partial substitution of Pr for La in La(Fe0.88Si0.12)13. The value of TC for La0.5Pr0.5(Fe0.88Si0.12)13Hy increases from 185 to 324 K with increasing y from 0 to 1.6. The maximum value of the isothermal magnetic entropy change ,Sm MAX is slightly decreased by hydrogen absorption. However, ,Sm MAX = -26 J/kg K in a magnetic field change of 5 T for La0.5Pr0.5(Fe0.88Si0.12)13H1.6 is still larger than the value of -23 J / kg K for La(Fe0.88Si0.12)13H1.5 having almost the same value of TC. Consequently, ,Sm MAX of the La0.5Pr0.5(Fe0.88Si0.12)13Hy is larger than that of La(Fe0.88Si0.12)13Hy in a wide temperature range covering room temperature.

Enhancement of Magnetocaloric Effects in Single Phase La1-zNdz(Fe0.88S 0.12)13

2007 ◽  
Vol 561-565 ◽  
pp. 1093-1096 ◽  
Author(s):  
S. Fujieda ◽  
A. Fujita ◽  
Kazuaki Fukamichi
Keyword(s):  
Single Phase ◽  
Entropy Change ◽  
Ferromagnetic State ◽  
Partial Substitution ◽  
Cooling Power ◽  
Itinerant Electron ◽  
Magnetic Field Change ◽  
First Order Transition ◽  
Cure Temperature ◽  
The Magnetic Field

The single phase of a cubic NaZn13-type La1-zNdz(Fe0.88Si0.12)13 is obtained in the region z ≤ 0.2. The field-induced first-order transition from the paramagnetic to ferromagnetic state, that is, the itinerant-electron metamagnetic (IEM) transition is kept after the substitution of Nd. In addition, a discontinuous change of magnetization at the Cure temperature becomes larger with increasing z. As a result, the isothermal magnetic entropy change and the relative cooling power in the magnetic field change from 0 to 5 T increase to –27 J/kg K and 518 J/kg, respectively, by the partial substitution of z = 0.2.

Refrigerant Capacity and Magnetocaloric Effect on LaFe11.1Co0.8Si1.1BX Alloys

2011 ◽  
Vol 84-85 ◽  
pp. 667-670
Author(s):  
Guo Qiu Xie
Keyword(s):  
Magnetocaloric Effect ◽  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Entropy Change ◽  
Magnetic Entropy ◽  
Field Change ◽  
Refrigerant Capacity ◽  
Structure Phase ◽  
Magnetic Field Change ◽  
Cubic Structure

In this paper, we report on the structure, magnetic properties and magnetocaloric effect in NaZn13-type LaFe11.1Co0.8Si1.1Bxalloys close to room temperature. The stable NaZn13cubic structure phase (space group isFm-3c) can easily obtained by annealing at 1080 °C for 225 hours. The maximal values of magnetic entropy change for LaFe11.1Co0.8Si1.1Bx(x=0.2, 0.25) were found to be 5.3 and 5.9 J/kg K at Curie temperature for a magnetic field change in 0-1.5 T, respectively. The calculated refrigerant capacity for a field change in 0–1.5 T is about 147 and 107 J/kg K, for LaFe11.1Co0.8Si1.1B0.2and LaFe11.1Co0.8Si1.1B0.25respectively, which is as larger as those of Gd(99.3%) alloy

Magnetic refrigeration with GdN by Active Magnetic Refrigerator cycle

2011 ◽  
Vol 1310 ◽  
Author(s):  
Yusuke Hirayama ◽  
Hiroyuki Okada ◽  
Takashi Nakagawa ◽  
Takao. A. Yamamoto ◽  
Takafumi Kusunose ◽  
...  
Keyword(s):  
Magnetic Entropy Change ◽  
Hot Isostatic Pressing ◽  
Entropy Change ◽  
Magnetic Refrigeration ◽  
Zero Field ◽  
Active Magnetic Regenerator ◽  
Magnetic Field Change ◽  
Total Temperature ◽  
The Magnetic Field ◽  
Magnetic Regenerator

ABSTRACTA magnetic refrigeration test was performed using a test device filled with spherical GdN material synthesized by the hot isostatic pressing (HIP) method. Refrigeration with an active magnetic regenerator cycle was tested in the temperature range between 48 and 66 K, with the field changing from 1.2 to 3.7 T and 2.0 to 4.0 T at upper and lower sides of the regenerator bed filled with the GdN spheres, respectively. Temperature spans about of 2 K were obtained at both sides, and the total temperature span in each cycle attained about 5 K. The specific heat of the material was measured to calculate the magnetic entropy change ΔS and the adiabatic temperature change ΔT induced by the magnetic field change ΔH. It was suggested that for a given ΔH, larger ΔS and ΔT can be exploited when demagnetized to lower H, especially, to zero field.

Room Temperature Magnetocaloric Effect of the Cox(MnSb)1-x Compounds

2013 ◽  
Vol 683 ◽  
pp. 56-59 ◽  
Author(s):  
Jian Hua Lin ◽  
Shan Dong Li ◽  
Li Li Wang ◽  
Jie Qiu ◽  
Zhi Yi Cai ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetocaloric Effect ◽  
Room Temperature ◽  
Magnetic Entropy Change ◽  
Magnetic Hysteresis ◽  
Entropy Change ◽  
Magnetic Entropy ◽  
Thermal Lag ◽  
Magnetocaloric Materials ◽  
Curie Temperature Tc

The room-temperature magnetocaloric effect (MCE) of Cox(MnSb)1-x (x=0.07, 0.15, 0.24) alloys has been investigated. It is revealed that the Curie temperature TC and the magnetic entropy change ΔSM are sensitive to the Co content x. When x=0.15, the MCE of Co0.15(MnSb)0.85 alloy is optimal with ΔSM=1.8 J/kg.K at 324 K under an applied magnetic field of 3 T. A second-order phase transformation occurs around TC, and the magnetic hysteresis loss thermal lag is negligible. These features demonstrate that Co0.15(MnSb)0.85 alloy is a promising room-temperature magnetocaloric materials.

scholarly journals Reversibility of the Magnetocaloric Effect in the Bean-Rodbell Model

2021 ◽  
Vol 7 (5) ◽  
pp. 60
Author(s):  
Luis M. Moreno-Ramírez ◽  
Victorino Franco
Keyword(s):  
Magnetic Field ◽  
Thermal Hysteresis ◽  
Entropy Change ◽  
Second Order ◽  
Zero Field ◽  
First Order ◽  
Magnetic Field Change ◽  
Magnetocaloric Materials ◽  
Moderate Magnetic Field ◽  
The Magnetic Field

The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the modification of the η parameter (η<1 for second-order and η>1 for first-order ones). The response is quantified via the Temperature-averaged Entropy Change (TEC), which has been shown to be an easy and effective figure of merit for magnetocaloric materials. A strong magnetic field dependence of TEC is found for first-order transitions, having a significant increase when the magnetic field is large enough to overcome the thermal hysteresis of the material observed at zero field. This field value, as well as the magnetic field evolution of the transition temperature, strongly depend on the atomic magnetic moment of the material. For a moderate magnetic field change of 2 T, first-order transitions with η≈1.3−1.8 have better TEC than those corresponding to stronger first-order transitions and even second-order ones.

The Magnetocaloric Effect in Ni-Mn-X (X=Ga, in) Heusler Alloys and Manganites with Magnetic Transition close to Room Temperature

2010 ◽  
Vol 168-169 ◽  
pp. 165-168
Author(s):  
Vasiliy D. Buchelnikov ◽  
Mikhail Drobosyuk ◽  
E.A. Smyshlyaev ◽  
O.O. Pavlukhina ◽  
A.V. Andreevskikh ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetocaloric Effect ◽  
Room Temperature ◽  
Direct Method ◽  
Magnetic Transition ◽  
Heusler Alloys ◽  
Field Change ◽  
Adiabatic Temperature Change ◽  
Magnetic Field Change ◽  
The Magnetic Field

The magnetocaloric effect (MCE) in theNi2+xMn1-xGa (x = 0.33, 0.36, 0.39), Ni50Mn25In25, Ni54Mn21Ga18In7, Ni53.5Mn21.5Ga16In9, Ni45Co5Mn36.5In13.5 Heusler alloys and in the La0.7BayCa0.3-yMnO3 (y = 0.12, 0.24, 0.3) manganites at the Curie points have been measured by the direct method. For the magnetic field change H = 2 T, the maximal adiabatic temperature change Tad in the Ni2+xMn1-xGa alloys is larger than 0.6 K. For the Ni50Mn25In25 alloy the maximal value of Tad = 1.51 K (for the same magnetic field change H = 2 T) is observed at the magnetic phase transition temperature.

Sign in / Sign up

Export Citation Format

Share Document