Structural and magnetic properties of Fe2P-type R6TX2 compounds (R=Zr, Dy, Ho, Er, T=Mn, Fe, Co, Cu, Ru, Rh, X=Sb, Bi, Te)

Structural analysis of Gd6FeBi2 from single-crystal X-ray diffraction methods and electronic structure calculations

“…Since the almost simultaneous reports on the first member, i.e. Ho 6 FeSb 2 , by two independent research groups (Morozkin, 2003;Zeng & Zhao, 2004), hundreds of compounds have been found to adopt the same crystal structure (Morozkin et al, 2011). The structure is commonly ISSN 2053ISSN -2296 # 2019 International Union of Crystallography referred to as the Zr 6 CoAl 2 -type structure, and it represents an ordered variant of the Fe 2 P structure.…”

Tunable Magnetic Exchange between Rare-Earth Metal 5d and Iron 3d States: A Case Study of the Multiple Magnetic Transitions in Gd6FeBi2 and the Solid Solutions Dy6–xGdxFeBi2 (1 ≤ x ≤ 5) with Curie Temperatures in the Range 120–350 K

“…Compared with other heavy RE elements, Gd has a 5d electron with a larger spatial wave function than that of 6s electrons, and thus, it is possible for Fe in Gd 6 FeBi 2 to carry a magnetic moment resulted from the overlap between Fe 3d electron wave function and neighboring Gd 5d electron wave function. Morozkin et al analyzed the relationship between lattice parameters and atomic radii of constituent elements in many members in the big family, suggesting that the RE and transition-metal nature determine the lattice parameter c . Generally, a higher spin yields a larger atomic size, and thus, the Fe spin will give a larger lattice c in Gd 6 FeBi 2 compared to Fe atoms without net spin, accounting for the larger c than the linearly extrapolated value from structures with nonmagnetic Fe.…”

“…A good example of such systems is the extended family RE 6 TX 2 (“6-1-2”), − where X is a p-block element, and among more than a hundred isotypic compounds known to date, no net spin contribution from T is commonly observed. , A notable exception is the phase Gd 6 FeBi 2 , which is a known room-temperature magnet . In the literature, the “6-1-2” series is often referred to as belonging to the Zr 6 CoAl 2 structure type, although from a purely crystallographic point of view, a classification with the anti-K 2 UF 6 type is also in order.…”

“…The compounds of this structure type are widely spread over the periodic table. The best-known and most-studied RE 6 TX 2 are those with RE = Gd–Tm and Lu; T = Mn, Fe, Co, Ni, and Ru; and X = Al, Ga, Sn, As, Sb, Bi, S, Se, and Te, and for some of them, neutron scattering experiments have been used to determine the magnetic structure. − As already mentioned, most members have low magnetic ordering temperatures, whereas Gd 6 FeBi 2 is shown to have a Curie temperature T c approaching 350 K . The ordering temperature of Gd 6 FeBi 2 is even higher than that of the prototypical magnetocaloric Gd 5 X 4 ( X = Si, Ge) compounds, where the enhanced exchange is due to strong Gd– X interactions, instead of the common in RE -based compounds Ruderman–Kittel–Kasuya–Yosida (RKKY) interactions …”

Crystal structure and magnetic properties of novel R3Co2.2Si1.8 compounds (R=Y, Gd–Tm)

“…We suggest that a type of distortion of the initial Mg-type lattice (lattice parameters, magnitude of distortion, symmetry of the resulting rare-earth sublattice), type of p-elements and transition metals determine the magnetic properties of resulting compounds. From this point of view, structural features of compounds of the present family of two-layer orthorhombic structures should be analyzed to derive empirical rules in order to predict their magnetic properties as it has been done for Fe 2 P-type compounds and their solid solution [29]. The present paper is a starting point in such investigation.…”