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Excellent magnetocaloric properties in RE 2 Cu 2 Cd ( RE   =   Dy and Tm) compounds and its composite materials

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ABSTRACT

The magnetic properties and magnetocaloric effect (MCE) of ternary intermetallic RE2Cu2Cd (RE = Dy and Tm) compounds and its composite materials have been investigated in detail. Both compounds undergo a paramagnetic to ferromagnetic transition at its own Curie temperatures of TC ~ 48.5 and 15 K for Dy2Cu2Cd and Tm2Cu2Cd, respectively, giving rise to the large reversible MCE. An additionally magnetic transition can be observed around 16 K for Dy2Cu2Cd compound. The maximum values of magnetic entropy change (−ΔSMmax) are estimated to be 17.0 and 20.8 J/kg K for Dy2Cu2Cd and Tm2Cu2Cd, for a magnetic field change of 0–70 kOe, respectively. A table-like MCE in a wide temperature range of 10–70 K and enhanced refrigerant capacity (RC) are achieved in the Dy2Cu2Cd - Tm2Cu2Cd composite materials. For a magnetic field change of 0–50 kOe, the maximum improvements of RC reach 32% and 153%, in comparison with that of individual compound Dy2Cu2Cd and Tm2Cu2Cd. The excellent MCE properties suggest the RE2Cu2Cd (RE = Dy and Tm) and its composite materials could be expected to have effective applications for low temperature magnetic refrigeration.

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Temperature dependence of magnetization (M, left scale) and the reciprocal susceptibility (1/χ, right scale) for Dy2Cu2Cd (a) and Tm2Cu2Cd (b) compounds under the magnetic field of H = 10 kOe, respectively.
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f2: Temperature dependence of magnetization (M, left scale) and the reciprocal susceptibility (1/χ, right scale) for Dy2Cu2Cd (a) and Tm2Cu2Cd (b) compounds under the magnetic field of H = 10 kOe, respectively.

Mentions: Figure 1(a,b) show the temperature dependence of the zero field cooled (ZFC) and field cooled (FC) magnetization M under different magnetic fields for Dy2Cu2Cd and a magnetic field of 2 kOe for Tm2Cu2Cd, respectively. Both compounds display a typical paramagnetic to ferromagnetic (PM-FM) transition, and the Curie temperatures TC, corresponding to the peak of dMFC/dT - T curve [inset of Fig. 1(b)], are determined to be 48.5 K and 15 K for Dy2Cu2Cd and Tm2Cu2Cd, respectively. Another magnetic transition can be observed for Dy2Cu2Cd around TS ~ 16 K under low magnetic fields and it shifts to much lower temperatures with increasing magnetic field. Such behaviours may arise from a spin glass transition or spin reorientation phenomenon2425, a systematically detail study of the lower temperature magnetic transition will be performed later. The transition temperatures are in good agreement with previously reported values in the literatures20. Figure 2(a,b) show the temperature dependence of the magnetization M (left side) and the reciprocal susceptibility 1/χ (right side) for Dy2Cu2Cd and Tm2Cu2Cd compounds under a magnetic field of 10 kOe, respectively. The 1/χ in paramagnetic regime from 80 to 298 K obeys the Curie-Weiss law for both compounds. The fitted lines are a guide to the eyes for Dy2Cu2Cd and Tm2Cu2Cd compounds as shown in the insets of Fig. 2(a,b), respectively. The fit to the Curie-Weiss formula yields positive paramagnetic Curie temperatures (θP), θP = 45.3 K for Dy2Cu2Cd and θP = 14.1 K for Tm2Cu2Cd, respectively, suggesting dominant ferromagnetic interactions. The effective magnetic moments (μeff) are 10.84 μB and 7.72 μB for Dy2Cu2Cd and Tm2Cu2Cd, respectively. Such moments are close to those of the free ion values of Dy and Tm taking the theoretical RE3+ moment of 10.86 μB and 7.56 μB, respectively.


Excellent magnetocaloric properties in RE 2 Cu 2 Cd ( RE   =   Dy and Tm) compounds and its composite materials
Temperature dependence of magnetization (M, left scale) and the reciprocal susceptibility (1/χ, right scale) for Dy2Cu2Cd (a) and Tm2Cu2Cd (b) compounds under the magnetic field of H = 10 kOe, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5035927&req=5

f2: Temperature dependence of magnetization (M, left scale) and the reciprocal susceptibility (1/χ, right scale) for Dy2Cu2Cd (a) and Tm2Cu2Cd (b) compounds under the magnetic field of H = 10 kOe, respectively.
Mentions: Figure 1(a,b) show the temperature dependence of the zero field cooled (ZFC) and field cooled (FC) magnetization M under different magnetic fields for Dy2Cu2Cd and a magnetic field of 2 kOe for Tm2Cu2Cd, respectively. Both compounds display a typical paramagnetic to ferromagnetic (PM-FM) transition, and the Curie temperatures TC, corresponding to the peak of dMFC/dT - T curve [inset of Fig. 1(b)], are determined to be 48.5 K and 15 K for Dy2Cu2Cd and Tm2Cu2Cd, respectively. Another magnetic transition can be observed for Dy2Cu2Cd around TS ~ 16 K under low magnetic fields and it shifts to much lower temperatures with increasing magnetic field. Such behaviours may arise from a spin glass transition or spin reorientation phenomenon2425, a systematically detail study of the lower temperature magnetic transition will be performed later. The transition temperatures are in good agreement with previously reported values in the literatures20. Figure 2(a,b) show the temperature dependence of the magnetization M (left side) and the reciprocal susceptibility 1/χ (right side) for Dy2Cu2Cd and Tm2Cu2Cd compounds under a magnetic field of 10 kOe, respectively. The 1/χ in paramagnetic regime from 80 to 298 K obeys the Curie-Weiss law for both compounds. The fitted lines are a guide to the eyes for Dy2Cu2Cd and Tm2Cu2Cd compounds as shown in the insets of Fig. 2(a,b), respectively. The fit to the Curie-Weiss formula yields positive paramagnetic Curie temperatures (θP), θP = 45.3 K for Dy2Cu2Cd and θP = 14.1 K for Tm2Cu2Cd, respectively, suggesting dominant ferromagnetic interactions. The effective magnetic moments (μeff) are 10.84 μB and 7.72 μB for Dy2Cu2Cd and Tm2Cu2Cd, respectively. Such moments are close to those of the free ion values of Dy and Tm taking the theoretical RE3+ moment of 10.86 μB and 7.56 μB, respectively.

View Article: PubMed Central - PubMed

ABSTRACT

The magnetic properties and magnetocaloric effect (MCE) of ternary intermetallic RE2Cu2Cd (RE = Dy and Tm) compounds and its composite materials have been investigated in detail. Both compounds undergo a paramagnetic to ferromagnetic transition at its own Curie temperatures of TC ~ 48.5 and 15 K for Dy2Cu2Cd and Tm2Cu2Cd, respectively, giving rise to the large reversible MCE. An additionally magnetic transition can be observed around 16 K for Dy2Cu2Cd compound. The maximum values of magnetic entropy change (−ΔSMmax) are estimated to be 17.0 and 20.8 J/kg K for Dy2Cu2Cd and Tm2Cu2Cd, for a magnetic field change of 0–70 kOe, respectively. A table-like MCE in a wide temperature range of 10–70 K and enhanced refrigerant capacity (RC) are achieved in the Dy2Cu2Cd - Tm2Cu2Cd composite materials. For a magnetic field change of 0–50 kOe, the maximum improvements of RC reach 32% and 153%, in comparison with that of individual compound Dy2Cu2Cd and Tm2Cu2Cd. The excellent MCE properties suggest the RE2Cu2Cd (RE = Dy and Tm) and its composite materials could be expected to have effective applications for low temperature magnetic refrigeration.

No MeSH data available.


Related in: MedlinePlus