Detailed study of NdFe2 and additional results relative to PrFe 2 and YbFe2. Comparison with other R.E. Fe2 compounds

Abstract

Résumé. 2014 Cet article termine l'étude des trois composés phases de Laves YbFe2, NdFe2 et PrFe2. Les number of techniques including X-ray diffraction, magnetization measurements, 143Nd N.M.R., 57Fe Mössbauer effect and neutron diffraction. Some data is also reported on PrFe2 and YbFe2. The characteristics of these three compounds are compared with those of the rest of the RFe2 series leading to the following conclusions : a) the crystalline field at the Rare Earth is not constant throughout the series, b) the isotropic part of the hyperfine field at the iron includes a Lorentz term together with spin and (probably) orbital transferred contributions arising from the R.E., c) the anisotropic part of the hyperfine field only partly results from dipolar effects and seems to involve both an intrinsic d band contribution and a transferred contribution from the R.E., d) the hyperfine field at the Rare Earth nucleus is higher than the free ion hyperfine field in the second half of the series and lower in the first half of the series these deviations probably resulting from both self polarization effects and transferred fields from the iron.

Hyperfine Interactions of111Cd in Some Rare Earth Laves Phases RT2 (T = Mn, Fe)

“…The samples of GdFe 2 and YbFe 2 were of the pure cubic C15 structure, and their Mo È ssbauer spectra well reproduced those published elsewhere (see, e.g. [4]), excluding a small (`10%) admixture of an unidentified nonmagnetic phase. The sample of YMn 2 was of the hexagonal C14 structure in accord with the data [13].…”

“…due to the R±Fe interaction is very small as compared to the m.h.f. created by the total 4f-moment [4]. It should be noted that it is difficult to distinguish between the contributions due to the 4f±5d interaction and the volume effect (the lanthanide contraction).…”

Understanding the element segregation and phase separation in the Ce-substituted Nd-(Fe,Co)-B based alloys

“…We suggest here that the existence of REFe 2 phase be responsible for Ce segregation. It was established that the large atom radius prevent to obtain stable NdFe 2 , LaFe 2 , PrFe 2 and YbFe 2 phases 27 . Cannon et al .…”

Magnetostrictive properties of the heavy-rare-earth-free Sm1-xNdxFe2 compounds

“…8 Figure 2(b) shows the composition dependence of the Curie temperature T C of the MgCu 2 -type phase of Sm 1Àx Nd x Fe 2 alloys. It is seen that, due to the lower T C of NdFe 2 (578 K) 4 compared with SmFe 2 , T C decreases from 675 K to 655 K with x increasing from 0 to 0.30. Figure 3 shows the thermomagnetic (Zero Field Cooling, ZFC) curves of Sm 1Àx Nd x Fe 2 alloys at an applied field of 50 Oe.…”

“…3 NdFe 2 has the same anisotropy sign as DyFe 2 but much smaller positive magnetostriction (2000 ppm at 0 K). 4 Hari Babu et al have investigated the magnetostrictive properties of Sm 1Àx Nd x Fe 1.93 . A polycrystalline magnetostriction as large as À1572 ppm was found for Sm 0.88 Nd 0.12 Fe 1.93 due to the anisotropy compensation between Sm 3þ and Nd 3þ ions.…”