中国物理B ›› 2010, Vol. 19 ›› Issue (3): 37502-037502.doi: 10.1088/1674-1056/19/3/037502

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Giant magnetocaloric effect in the Gd5Ge2.025Si1.925In0.05 compound

E. Yüzüak, I. Dincer, Y. Elerman   

  1. Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100} Besevler, Ankara, Turkey
  • 收稿日期:2009-04-14 修回日期:2009-07-10 出版日期:2010-03-15 发布日期:2010-03-15

Giant magnetocaloric effect in the Gd5Ge2.025Si1.925In0.05 compound

E. Yüzüak†, I. Dincer, and Y. Elerman   

  1. Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Besevler, Ankara, Turkey
  • Received:2009-04-14 Revised:2009-07-10 Online:2010-03-15 Published:2010-03-15

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摘要： The magnetocaloric properties of the Gd5Ge2.025Si1.925In0.05 compound have been studied by x-ray diffraction, magnetic and heat capacity measurements. Powder x-ray diffraction measurement shows that the compound has a dominant phase of monoclinic Gd5Ge2Si2-type structure and a small quantity of Gd5(Ge,Si)3-type phase at room temperature. At about 270 K, this compound shows a first order phase transition. The isothermal magnetic entropy change (Δ SM) is calculated from the temperature and magnetic field dependences of the magnetization and the temperature dependence of MCE in terms of adiabatic temperature change (Δ Tad) is calculated from the isothermal magnetic entropy change and the temperature variation in zero-field heat-capacity data. The maximum Δ SM is -13.6~J.kg-1.k-1 and maximum Δ Tad is 13~K for the magnetic field change of 0--5~T. The Debye temperature (θD) of this compound is 149~K and the value of DOS at the Fermi level is 1.6 states/eV.atom from the low temperature zero-field heat-capacity data. A considerable isothermal magnetic entropy change and adiabatic temperature change under a field change of 0--5~T jointly make the Gd5Ge2.025Si1.925In0.05 compound an attractive candidate for a magnetic refrigerant.

Abstract: The magnetocaloric properties of the Gd5Ge2.025Si1.925In0.05 compound have been studied by x-ray diffraction, magnetic and heat capacity measurements. Powder x-ray diffraction measurement shows that the compound has a dominant phase of monoclinic Gd5Ge2Si2-type structure and a small quantity of Gd5(Ge,Si)3-type phase at room temperature. At about 270 K, this compound shows a first order phase transition. The isothermal magnetic entropy change ($\Delta$ SM) is calculated from the temperature and magnetic field dependences of the magnetization and the temperature dependence of MCE in terms of adiabatic temperature change ($\Delta$ Tad) is calculated from the isothermal magnetic entropy change and the temperature variation in zero-field heat-capacity data. The maximum $\Delta$ SM is -13.6 J$\cdot$kg-1$\cdot$K-1 and maximum $\Delta$ Tad is 13 K for the magnetic field change of 0--5 T. The Debye temperature ($\theta$D) of this compound is 149 K and the value of DOS at the Fermi level is 1.6 states/eV.atom from the low temperature zero-field heat-capacity data. A considerable isothermal magnetic entropy change and adiabatic temperature change under a field change of 0--5 T jointly make the Gd5Ge2.025Si1.925In0.05 compound an attractive candidate for a magnetic refrigerant.

Key words: magnetic properties, magnetocaloric effect, isothermal magnetic entropy change, adiabatic temperature change

中图分类号:  (Magnetocaloric effect, magnetic cooling)

  • 75.30.Sg
75.40.Cx (Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)) 75.30.Kz (Magnetic phase boundaries (including classical and quantum magnetic transitions, metamagnetism, etc.)) 61.66.Dk (Alloys ) 71.20.Lp (Intermetallic compounds) 75.60.Ej (Magnetization curves, hysteresis, Barkhausen and related effects)