Magnetic properties and magnetocaloric effect of Gd(Ni_1–xFe_x)₃ crystalline compound and powder

Abstract

In the paper we present and discuss magnetic properties of the Gd(Ni1–x Fex)3 crystalline compounds and their ball‐milled powders in a context of the magnetocaloric effect (MCE). Moreover, based on the obtained results, powders and composites with non‐magnetic (Cu) and magnetic (Fe) additions were prepared. Magnetic quantities such as the Curie temperature, the saturation magnetization and the MCE (as a magnetic entropy change) were determined for all examined samples. In the case of the bulk crystalline compounds a partial substitution of Ni by Fe atoms causes a decrease of the saturation magnetization as well as the MCE and an increase of the Curie temperature. Samples with x ranging from 0.1 to 0.15 show the best potential for room‐temperature refrigeration. Pulverization of the tested compounds leads to formation of flake‐like grains with thickness less than 1 μm. Such grinding causes a decrease of the Curie temperature (by about 10 K) as well as the MCE (by about 50%) in a comparison with the crystalline samples. In the case of the composite with magnetic addition an enhancement of the MCE was observed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Hyperfine interactions in R x Gd1− x Fe3 intermetallics R = Tb, Y

“…However, in this case such an increase is much more faster and M S equals 5.32μ B /f.u for YFe 3 compound. The observed M S (x) variation in both series may suggest the antiparallel type of coupling between R(4f) and Fe(3d) magnetic moments which strongly depend on the 4f − 3d exchange interactions and are realized via 4f−5d/4d as well as 5d/4d−3d interactions [5][6][7][8]12]. So, the magnitude of the iron magnetic moment is related to the interaction within 3d band and between 4f−3d bands.…”

“…As it was previously reported the values of the total magnetic moment varies with R, e.g in the case of GdFe 3 [1,[5][6][7][8][9][10][11][12]. The substitution within rare earth sublattice may lead to the changes of ff interactions which are mostly realized by 5d−3d hybridization.…”

“…The series of the RFe 3 compounds where R is rare earth element exhibits very interesting magnetic properties due to the combination of 3d itinerant and 4f localized magnetism [1][2][3][4][5][6]. Moreover, they attracted a great deal of attention not only by the academics but also due to their possible application as permanent magnet materials.…”

Influence of Transition Metal Substitution on the Low-Field Magnetic Properties in the Gd(Ni1-xTx)3 (T = Fe, Co) Intermetallic Compounds

“…Partially replacing of Ni atoms by other 3d elements leads to changes in magnetic properties correlated with the electronic structure [1][2][3][4][5][6][7]. One of previously studied series is Gd(Ni 1¡x T x q 3 , where T = Fe or Co [5,[8][9][10][11]. The doping in the 3d sublattice the same amount of Co or Fe with different ionic radius (Fe -0.77 Å, Co -0.74 Å) and different number of 3d electrons (Fe -3d 6 , Co -3d 7 q causes appearing of different local environment of R atoms.…”

“…The doping in the 3d sublattice the same amount of Co or Fe with different ionic radius (Fe -0.77 Å, Co -0.74 Å) and different number of 3d electrons (Fe -3d 6 , Co -3d 7 q causes appearing of different local environment of R atoms. It is reflected in the change of: the volume of the unit cell, the Curie temperature, the saturation magnetization, the magnetization on 3d atom, the magnetocaloric effect (MCE) and the intensity of states at the Fermi level [8][9][10][11].…”