Articles you may be interested inLarge magnetocaloric effect with a wide working temperature span in the R2CoGa3 (R=Gd, Dy, and Ho) compounds Large magnetocaloric effects over a wide temperature range in MnCo1−xZnxGe Magnetocaloric effect of Ho-, Dy-, and Er-based bulk metallic glasses in helium and hydrogen liquefaction temperature range Appl.The compound Ho 2 In exhibits two successive magnetic phase transitions: a spin-reorientation transition at T SR = 32 K and a magnetic-ordering transition at T C = 85 K. The maximum reversible −⌬S M values are 6.3 and 11.2 J/kg K at T SR and T C , respectively, for a field change of 5 T. These two −⌬S M peaks with the same sign are partly overlapping, which results in a wide temperature interval with appreciable magnetocaloric effect. The results on Ho 2 In indicate that materials with successive SR and magnetic-ordering transitions may constitute an important new class of magnetic refrigerants since they work in a wider temperature range than the conventional refrigerant materials.

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A large reversible negative magnetic-entropy change ⌬S M has been observed in TbCoC 2 , accompanied by a second-order phase transition at 28 K. The maximum value of −⌬S M is 15.3 J kg −1 K −1 at 30 K for a magnetic-field change from 0 to 5 T, with the refrigerant capacity of 354 J kg −1. In particular, also the large −⌬S M max of 7.8 J kg −1 K −1 , is obtained for a small field change from 0 to 2 T. The large reversible ⌬S M and the high reversible refrigerant capacity in low magnetic field indicate that TbCoC 2 may be a promising candidate for magnetic refrigeration at low temperatures.

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Dy 2 O 3 -coated Dy nanoparticles and Al 2 O 3 -coated Dy nanocapsules, with Dy cores with the average size of 3.6 and 17.6 nm, respectively, are synthesized by arc-discharge technique. The transition from ferromagnetism to antiferromagnetism absents in the Dy nanoparticles, due to that its average core size of 3.6 nm is smaller than the helix period of Dy. The temperature of the superparamagnetismantiferromagnetism transition in the Dy nanocapsules increases abnormally to 105 K, while the Néel temperature decreases to 150 K. The magneticentropy change (-DS m ) of the Dy nanoparticles rapidly increases with decreasing temperature. For Al 2 O 3 -coated Dy nanocapsules, -DS m reaches 15.2 J kg -1 K -1 at 7.5 K, due to the existence of superparamagnetism, and a peak (5.2 J kg -1 K -1 ) appears at 105 K due to the superparamgantism-antiferromagnetism transition, and -DS m exceeds 2 J kgin the temperature range from 7.5 to 105 K, for a field change from 1 to 5 T.