Magnetization measurements have been carried out on the melt-spun ribbon sample of the rare earth intermetallic compound DyNi (Orthorhombic, FeB-type, Space group Pnma) and its magnetic and magnetocaloric properties are compared with those of the arc-melted analog. The arc-melted DyNi orders ferromagnetically at around 61 K (TC) whereas the melt-spun DyNi orders ferromagnetically at about 47 K. The maximum isothermal magnetic entropy change, ∆Smmax, near TC of the arc-melted and the melt-spun DyNi is found to be −32.7 J/kg K and −22.4 J/kg K, respectively, for a field change of 140 kOe. For low magnetic field changes of ~20 kOe, the relative cooling power (RCP) is ~660 J/kg for the arc melted DyNi and ~460 J/kg for the melt-spun ribbon. The reduction in TC and magnetocaloric effect may be attributed to the microstructure-induced anisotropy developed during the melt-spinning process. © 2016 Elsevier B.V.

R. Nirmala

Department Of Physics

R. Rajivgandhi

Earth (planet)

INTERMETALLICS

Magnetism

Melt spinning

microstructure

Rare earth alloys

Rare earths

Isothermal magnetic entropy change

Low magnetic fields

Magnetization measurements

Magnetocaloric properties

MELT SPINNING PROCESS

RARE EARTH INTERMETALLIC COMPOUNDS

rare earth intermetallics

Relative cooling power

Magnetocaloric effects

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IIT Madras

Journal of Magnetism and Magnetic Materials

Equiatomic RNi (where R = Gd, Ho and Er) compounds have been prepared by undercooling. Magnetization data confirm ferromagnetic ordering of the samples at 69 K, 35 K and 10 K (TC) respectively. Magnetocaloric effect (MCE) has been estimated in terms of isothermal magnetic entropy change (ΔSm) near TC. The maximum ΔSm value (ΔSm max) for 50 kOe field change is about −18 Jkg-1K−1, −20 Jkg-1K−1 and −30 Jkg-1K−1 respectively near TC for the undercooled RNi (R = Gd, Ho and Er) compounds. The ΔSm max value is more than that obtained for the same compounds prepared by arc-melting and melt-spinning techniques. The observed enhancement in MCE of the undercooled samples could be due to the improved purity that results in faster change of magnetization around the magnetic transition. Thus undercooling rare earth intermetallics and alloys seems to be an attractive, alternative method to synthesize magnetocaloric materials. © 2019 Elsevier B.V.

Enhanced magnetocaloric effect in undercooled rare earth intermetallic compounds RNi (R = Gd, Ho and Er)

Magnetocaloric effect (MCE) in RNi (where R = Gd, Tb and Ho) compounds has been studied in their arc-melted and melt-spun forms. The compound GdNi has the orthorhombic CrB-type structure (Space group Cmcm, No. 63) and the compound HoNi has the orthorhombic FeB-type structure (Space group Pnma, No. 62) at room temperature regardless of their synthesis condition. However, arc-melted TbNi orders in a monoclinic structure (Space group P21/m, No. 11) and when it is rapidly quenched to a melt-spun form, it crystallizes in an orthorhombic structure (Space group Pnma, No. 62). The arc-melted GdNi, TbNi and HoNi compounds order ferromagnetically at ∼69 K, ∼67 K and ∼36 K (TC) respectively. While the melt-spun GdNi shows about 6 K increase in TC, the ordering temperature of TbNi remains nearly the same in both arc-melted and melt-spun forms. In contrast, a reduction in TC by about 8 K is observed in melt-spun HoNi, when compared to its arc-melted counterpart. Isothermal magnetic entropy change, ∆Sm, calculated from the field dependent magnetization data indicates an enhanced relative cooling power (RCP) for melt-spun GdNi for field changes of 20 kOe and 50 kOe. A lowered RCP value is observed in melt-spun TbNi and HoNi. These changes could have resulted from the competing shape anisotropy and the granular microstructure induced by the melt-spinning process. Tailoring the MCE of rare earth intermetallic compounds by suitably controlled synthesis techniques is certainly one of the directions to go forward in the search of giant magnetocaloric materials. © 2017 Elsevier B.V.

Effect of rapid quenching on the magnetism and magnetocaloric effect of equiatomic rare earth intermetallic compounds RNi (R = Gd, Tb and Ho)

Magnetic and magnetocaloric properties of cubic Laves phase RCoNi (R Gd, Tb, Dy, and Ho) compounds have been studied. The RCoNi (R Gd, Tb, Dy, and Ho) compounds order ferromagnetically at ∼200 K, ∼113 K, ∼68 K, and ∼42 K (TC), respectively. Field dependent magnetization data of RCoNi at 5 K in fields up to 7 T reveal saturation behaviour with minimal hysteresis. Magnetocaloric effect in terms of isothermal magnetic entropy change has been calculated. Maximum isothermal magnetic entropy change values of ∼-7.2 J/kg/K, ∼-10.1 J/kg/K, ∼-15.5 J/kg/K, and ∼-19.6 J/kg/K are obtained for RCoNi (R Gd, Tb, Dy, and Ho) compounds for 7 T field change close to TC. Substitution of 50 at. Ni in Co-site of RCo2 has led to the reduction of TC of the parent compounds by nearly one-half, but broadened the magnetic entropy change vs T curve and hence improved the relative cooling power. The large magnetocaloric effect associated with RCoNi compounds makes them potential candidates for low temperature magnetic refrigeration applications. © 2013 American Institute of Physics.

Fulltext

Journal of Applied Physics

Magnetocaloric effect in the rare earth intermetallic compounds RCoNi (R Gd, Tb, Dy, and Ho)

The European Physical Journal Plus

The structural, magnetic and above room temperature magnetocaloric properties of La0.5Sr0.5MnO3 compound

Chinese Physics B

Optimizing and fabricating magnetocaloric materials

Magnetic phase transition and magnetocaloric effect in Dy12Co7 compound

Applied Physics Letters

Texture-induced enhancement of the magnetocaloric response in melt-spun DyNi2 ribbons

Effect of microstructure and texture on the magnetic and magnetocaloric properties of the melt-spun rare earth intermetallic compound DyNi

Journal	Data powered by TypesetJournal of Magnetism and Magnetic Materials
Publisher	Data powered by TypesetElsevier B.V.
ISSN	03048853
Open Access	No