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ABSTRACT: Magnetic properties and magnetocaloric effects (MCEs) of the Dy3Co compound are studied. Two successive magnetic transitions: the antiferromagnetic (AFM)-to-AFM transition at T
AF
=29K and the AFM-to-paramagnetic (PM) transition with increasing temperature at the Néel temperature T
N
=44K are observed. Dy3Co undergoes a field-induced metamagnetic transition from the AFM to the ferromagnetic (FM) state belowT
N
, giving rise to a large MCE. The maximal value of magnetic entropy change ΔS
m
is −13.9J/kg K with a refrigerant capacity (RC) of 498J/kg around T
N
for a field change of 0–5T. Asign change of MCE in Dy3Co with magnetic field and temperature is observed near the critical field where the metamagnetic transition occurs.
Applied Physics A 04/2012; 99(4):853-858. · 1.63 Impact Factor
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ABSTRACT: Magnetocaloric effect (MCE) and magnetic phase transition of Ho3Co compound have been investigated. The two successive magnetic transitions: spin–reorientation transition at TSR = 8.5 K and antiferromagnetic (AFM)–paramagnetic transition at the Néel temperature TN = 21 K are observed. The Ho3Co compound undergoes a field-induced metamagnetic transition from AFM to ferromagnetic states below TN, which leads to a large MCE. The maximal value of magnetic entropy change (ΔSM) is found to be −14.5 J/kg K with a refrigerant capacity (RC) value of 440 J/kg around TN for a field change of 0–5 T. The large ΔSM as well as considerable RC in Ho3Co is very useful for applying it to the magnetic refrigeration in low-temperature ranges.
Journal of Applied Physics 03/2011; 109(7):07A931-07A931-3. · 2.17 Impact Factor
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ABSTRACT: The effect of the B-addition on magnetic entropy change ΔS<sub>M</sub> and hysteresis loss in La ( Fe , Si )<sub>13</sub> is studied. The maximal values of ΔS<sub>M</sub> for LaFe <sub>11.9</sub> Si <sub>1.1</sub> , LaFe <sub>11.5</sub> B <sub>0.4</sub> Si <sub>1.1</sub> , LaFe <sub>11.5</sub> Si <sub>1.5</sub> , and LaFe <sub>11.0</sub> B <sub>0.5</sub> Si <sub>1.5</sub> are found to be 27.0, 26.1, 23.7, and 21.2 J/kg K at Curie temperature T<sub> C </sub> for a field change in 0–5 T, respectively. The maximal hysteresis losses around T<sub> C </sub> are 43 and 21 J/kg for LaFe <sub>11.9</sub> Si <sub>1.1</sub> and LaFe <sub>11.5</sub> Si <sub>1.5</sub> , respectively, while almost no magnetic hysteresis is observed for the B-doped compounds. Our result reveals that a large ΔS<sub>M</sub> and a small hysteresis loss can be simultaneously achieved in NaZn <sub>13</sub> -type La ( Fe , Si )<sub>13</sub> compounds by the addition of B.
Journal of Applied Physics 06/2010; · 2.17 Impact Factor
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ABSTRACT: Magnetic properties and magnetocaloric effects (MCEs) of the antiferromagnetic (AFM) ErTiSi compound with a Néel temperature T<sub>N</sub>=46 K are studied by magnetization measurements. Two successive magnetic transitions in the thermomagnetic M-T curves, an AFM-AFM transition followed by an AFM-paramagnetic transition with increasing temperature, are observed. ErTiSi undergoes a field-induced metamagnetic transition from AFM to FM state below T<sub>N</sub> . A sign change in MCE with increasing temperature or magnetic field in ErTiSi is observed near the critical field. The maximal value of magnetic entropy change ΔS<sub> m </sub> is -8.9 J / kg K around T<sub>N</sub> for a field change of 0–5 T. The modest ΔS<sub> m </sub> as well as no hysteresis loss around T<sub>N</sub> in ErTiSi may be useful for its application in magnetic refrigeration.
Journal of Applied Physics 06/2010; · 2.17 Impact Factor
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ABSTRACT: The magnetic properties and magnetocaloric effects of the Gd <sub>6</sub> Co <sub>2</sub> Si <sub>3</sub> alloy are investigated. Gd <sub>6</sub> Co <sub>2</sub> Si <sub>3</sub> undergoes a reversible second-order magnetic transition with a Curie temperature at room temperature (T<sub>C</sub>=295 K ) . A broad distribution of the magnetic entropy change ΔS<sub>m</sub> peak is observed, and the full width at half maximum of the ΔS<sub>m</sub> peak is found to be about 111 K under a magnetic field of 5 T. The large value of the refrigerant capacity (RC) is found to be comparable with those of pure Gd, which have maximal RC values for all the magnetocaloric materials reported previously. The maximal value of ΔS<sub>m</sub> is 6.3 J/kg K for a field change of 0–5 T. Excellent magnetocaloric properties, especially considerable values of RC, indicate the applicability of Gd <sub>6</sub> Co <sub>2</sub> Si <sub>3</sub> for magnetic refrigeration in the room-temperature range.
Journal of Applied Physics 11/2009; · 2.17 Impact Factor
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Advanced Materials 07/2009; 21(37):3727 - 3729. · 13.88 Impact Factor
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ABSTRACT: The magnetic properties and magnetocaloric effect of amorphous alloys Ce <sub>2</sub> Fe <sub>23-x</sub> Mn <sub>x</sub> B <sub>3</sub> (1≤x≤6) were investigated. The magnetic properties are sensitive to the composition. For samples with x≤3 , the low fraction and isolated Fe–Mn antiferromagnetic (AFM) coupling simply align antiparallel to the majority ferromagnetic (FM) order and reduce the total magnetization but cause no noncollinearity; thus they are typical FM materials with T<sub>C</sub> decreasing drastically from 336 to 226 K and the magnetization has a sharp drop around respective T<sub>C</sub> without thermal hysteresis suggesting a second order phase transition resulting from their amorphous nature. For x=4 and 5, amorphous alloys Ce <sub>2</sub> Fe <sub>23-x</sub> Mn <sub>x</sub> B <sub>3</sub> experience two transitions: first a paramagnetic (PM)-FM second transition at 143 and 81 K, respectively, and then a FM–spin glass (SG) transition. A PM-SG transition occurs at the freezing temperature (T<sub>f</sub>) about 28.2 K for x=6 . The SG behavior in amorphous alloy Ce <sub>2</sub> Fe <sub>23-x</sub> Mn <sub>x</sub> B <sub>3</sub> can be attributed to the disordered structure resulting from their amorphous nature and the competition between the Fe–Fe FM coupling and Fe–Mn AFM negative coupling. The magnetic entropy change for alloys Ce <sub>2</sub> Fe <sub>23-x</sub> Mn <sub>x</sub> B <sub>3</sub> with x≤3 is calculated using the Maxwell relation.
Journal of Applied Physics 05/2009; · 2.17 Impact Factor
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ABSTRACT: The magnetic properties and magnetocaloric effects in NaZn13-type La1−xPrxFe10.7Co0.8Si1.5 compounds have been investigated. Partially replacing La with Pr leads to a small reduction in the Curie temperature TC due to the lattice contraction, but the values of TC for La1−xPrxFe10.7Co0.8Si1.5 are close to room temperature. The maximum values of magnetic entropy change ΔSm in La1−xPrxFe10.7Co0.8Si1.5 with x ≤ 0.5 are in the range 13.5–14.6 J kg−1 K−1 for a field change of 0–5 T, and correspondingly the values of the refrigerant capacity (RC) are 373–353 J kg−1. In particular, the values of ΔSm and RC for a low field change from 0 to 2 T are also obtained to be as high as 7.0–8.1 J kg−1 K−1 and 128–139 J kg−1, respectively. No magnetic hysteresis is observed in the magnetization as a function of both the temperature and the magnetic field in the La1−xPrxFe10.7Co0.8Si1.5 compounds. The large reversible ΔSm and the high reversible RC for a low field change indicate that La1−xPrxFe10.7Co0.8Si1.5 may be a promising candidate for magnetic refrigeration near room temperature.
Journal of Physics D Applied Physics 11/2008; 41(24):245005. · 2.54 Impact Factor
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ABSTRACT: Magnetic entropy change ΔSm, hysteresis loss and refrigerant capacity of NaZn13-type La0.7Pr0.3Fe13−xSix (1.5⩽x⩽2.0) compounds have been investigated. The Curie temperature TC increases linearly with the increase of silicon concentration. Although the maximum value of ΔSm under a field change of 0−5 T decreases from 30.5 to 11.4 J/kg K as x increases from 1.5 to 2.0, the hysteresis loss at TC reduces remarkably from 89.2 J/kg for x=1.5 to zero for x=2.0 because the increase of Si content can weaken the itinerant electron metamagnetic transition. The effective refrigerant capacity RCeff is maintained at high values of 362−439 J/kg for a field change of 0−5 T. This implies that a large ΔSm and a high RCeff can be achieved simultaneously in the La0.7Pr0.3Fe13−xSix compounds.
Journal of Magnetism and Magnetic Materials 321(15):2336-2339. · 1.78 Impact Factor
