Abstract
The Ce2Fe14B intermetallic, like Nd2Fe14B, has the tetragonal Nd2Fe14B-type structure (space group P42/mnm), in which Ce ions have a mixed-valence state characterized by the coexistence of trivalent 4f1 and tetravalent 4f0 electron states. Despite the fact that the saturation magnetization, magnetic anisotropy field, and Curie temperature of the Ce2Fe14B intermetallic are substantially lower than those of Nd2Fe14B and Pr2Fe14B, Ce2Fe14B retains the capacity of being able to be used in the manufacturing of rare-earth permanent magnets. Moreover, at low temperatures, the anisotropy field of Се2Fe14B is higher than that of Nd2Fe14B, and Се2Fe14B does not undergo the spin-reorientation transition. In this respect, studies of (Nd, Ce)-Fe-B alloys, which are intended for the improvement of the service characteristics-to-cost ratio, are very relevant. A model and algorithm for calculating the hysteresis loops of uniaxial hard magnetic materials with allowance for the K1 and K2 (K2 > 0 and K1 > 0 and K1 < 0) magnetic anisotropy constants were developed and allowed us to obtain data on their effect on the parameters of hysteresis loops for a wide temperature range (0–300 K). The simulation and analysis of hysteresis loops of the quasi-ternary intermetallics (Nd1−хСех)2Fe14B (х = 0–1) was performed. Results of the simulation indicate that the alloying of the Nd2Fe14B intermetallic with Ce to x = 0.94 (1) does not completely eliminate the negative effect of spin-reorientation phase transition on the residual magnetization of the (Nd1−хCeх)2Fe14B intermetallic and (2) slightly decreases the slope of magnetization reversal curve.
Highlights
IntroductionThe low cost of Ce-containing Nd-Fe-B permanent magnets, in some areas being a potential alternative to those based on expensive rare-earth elements (Nd, Pr, Dy, Tb), has stimulated considerable research efforts [1,2]
In recent years, the low cost of Ce-containing Nd-Fe-B permanent magnets, in some areas being a potential alternative to those based on expensive rare-earth elements (Nd, Pr, Dy, Tb), has stimulated considerable research efforts [1,2].Crystals 2020, 10, 518; doi:10.3390/cryst10060518 www.mdpi.com/journal/crystalsSimilar to the other R-Fe-B systems, the Ce-Fe-B system is characterized by the formation of the ternary intermetallic compound having a 2:14:1 stoichiometry and tetragonal Nd2 Fe14 B-type structure [3]
Stolyarov) used for the simulation of magnetic hysteresis loops of (Nd1−x Cex )2 Fe14 B intermetallics with the uniaxial tetragonal lattice, the following initial parameters are inputted: α is the angle made by an arbitrary plane and the X-axis [100] and the external magnetic field H is applied in this plane, θH is the angle made by the H field direction and Z-axis [001]
Summary
The low cost of Ce-containing Nd-Fe-B permanent magnets, in some areas being a potential alternative to those based on expensive rare-earth elements (Nd, Pr, Dy, Tb), has stimulated considerable research efforts [1,2]. Its uniaxial anisotropy is higher than that of R2 Fe14 B with R =La, Lu, Y [10], but lower than that of Nd2 Fe14 B at temperatures substantially higher than the spin-reorientation temperature It was predicted [11] that, theoretically, Ce atoms in the (Nd1−x Cex ) Fe14 B compounds occupy the 4g positions (large in volume); this is explained by atomic size effects. Below Tsr , the experimental magnetization reversal curves in negative magnetic fields exhibit a bending, which increases with decreasing temperature. V.L. Stolyarov) used for the simulation of magnetic hysteresis loops of (Nd1−x Cex ) Fe14 B intermetallics with the uniaxial tetragonal lattice, the following initial parameters are inputted: α is the angle made by an arbitrary plane and the X-axis [100] and the external magnetic field H is applied in this plane, θH is the angle made by the H field direction and Z-axis [001].
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