Influence of symmetry of the crystalline structure on the magnetic anisotropy of Tb2Co7

Abstract

It is known that the intermetallic compounds RT2, RT3, %T7, F$Tlg, and RT5 can form in the series of the rare-earth(R) and 3d(T) metal alloys. From the structural point of view the lattices of the compounds RT3, %T,, and F$TI9 a r e combinations of elementary parts F$T4 (2RT2) and RT5 packed along the common axis at symmetry of third order: 3RT3 = F$T4 + RT5, 2 5 T 7 = F$T4+ + 2RT5, %Tlg =R2T4 + 3RT5. If the packing of parts F$T corresponds t o the hexagonal Laves phase of the MgZ% type, the structure of the compounds belongs t o the space group R3/mmc (the hexagonal modification of the compounds RT3, %T,, %Tlg). When the parts %T4 a r e packed as in the cubic Laves phase of the M g C 3 type, the structure belongs to the space group m-m (the rhombohedral modification). Up t o now each of these compounds was prepared either as only one modification o r as an indivisible mixture of two phases. There was no compound obtained separately in both modifications.The Tb2C07 single crystals of the rhombohedra1 ( a ) modification were investigated in /l/, where an unusual type of three-axes magnetic anisotrow was observed. In our note single crystals of this compound in the hexagonal ( 8 ) modificiation a r e obtained and a comparison of magnetic properties is made for the same compound but with different symmetry of crystals. 4A determination of the modifications was carried out from the symmetry at the Laue patterns obtained at diffraction from the (110) and (100) crystallographic planes (along the axes a and b, respectively). In @-crystals a and b axes a r e the 1) Ke Karlovu 5,

Effects of Fe substitution on structural and magnetic properties of the Nd2Co7−xFex compounds

“…4. This observation is consistent with the report of Andreev et al [8] and Bartashevich et al [9], showing that the easy magnetization direction of Nd 2 Co 7 single crystal was along the a-axis below 225 K and along the c-axis above 290 K. In addition, the magnetization curve of Nd 2 Co 7 mimics that of NdCo 5 , implying a predominant contribution from the 1:5 slabs. The two spin-reorientation transitions are observed in the Fe substituted compounds Nd 2 Co 7−x Fe x for x < 1.5.…”

“…Andreev et al [8] and Bartashevich et al [9] reported that the magnetic structure of Nd 2 Co 7 experienced two fluctuations as temperature increases: a spinreorientation (SR) occurred around 225 K and another SR around 290 K, with an alteration of the easy magnetization direction (EMD) from a-axis below the first SR transition to the c-axis above the second SR transition. However, binary "R 2 Fe 7 " does not exist possibly due to much higher mixing enthalpy between R and Fe than that between R and Co [10].…”

Solid-state phase equilibria in the Co–Pt–Tb ternary system at 1173K

“…4(a)), which indicates no decomposition. However, when the alloy is annealed at 1273 and 1173 K, respectively, for 15 days, part decomposition for Co 5 Tb phase was observed, as shown in Fig. 4(b) and (c), when the alloy is annealed at 1173 K for 45 days, the Co 5 Tb phase can no longer be detected in the XRD pattern ( Fig.…”

“…The Co-Tb binary system phase equilibria had also been well studied [2][3][4], with the formation of five binary compounds Co 17 Tb 2 (Zn 17 Th 2 structure type), Co 5 Tb (CaCu 5 structure type), Co 7 Tb 2 (Co 7 Er 2 structure type), Co 3 Tb (Ni 3 Pu structure type) and Co 2 Tb (Cu 2 Mg structure type) having been discovered. Specific research about the Co 5 Tb compound showed it to be present after annealing at 1273 K for 100 h [5], however, its eutectoid decomposition reaction would take place at around 1083 K [6]. Thus, ones proposed it to be a high temperature phase or a metastable phase at low temperature [6,7].…”

Effect of hydrogen on magnetic properties of Lu2Fe14B single crystal

“…The magnetic properties of Lu 2 Fe 14 B [1,2,9,10] and its hydride [11] have been previously investigated on polycrystalline samples. Until now no data on the preparation of Lu 2 Fe 14 B single crystals and, moreover, of its hydride have been reported.…”