Rare Earth “Disilicides”

Structural chemistry, magnetism and electrical properties of binary Gd silicides and Ho3Si4

“…A least squares fit according Eq. (2) in the ferromagnetic state leads to an exponent α = 1.16 and in the antiferromagnetic state to α = 4.1. We note that this value α should be 3-4 for isotropic antiferromagnets [43] but 2 for isotropic ferromagnets [44] and supports the assumption of a rather complicated spin structure.…”

“…The line compound Gd 5 Si 3 is formed by the peritectic reaction: L + Gd 5 Si 4 → Gd 5 Si 3 at 1700 • C, while the other one Gd 5 Si 4 melts incongruently at 1725 • C. On the contrary, the monosilicide GdSi melts congruently at 1830 • C and does not have a significant homogeneity range. Both phases GdSi 2−x and GdSi ∼2 were the subject of controversy in literature [2][3][4][5][6][7][8][9]. Indeed, the stoichiometric composition of the silicide GdSi 2−x of AlB 2 type was attributed to the formula Gd 2 Si 3 (GdSi 1.5 , 60 at.% Si).…”

Ternary rare-earth alumo-silicides—single-crystal growth from Al flux, structural and physical properties

“…1), there was little evidence that the related RAl x Si 2Àx (R ¼ Sm or Gd) phases might be disordered as well. The choice of GdAlSi was also intended to verify the tetragonal symmetry derived from powder X-ray diffraction data-whereas RSi 2 or rather RSi 2Àx binary phases, where R ¼ La to Sm, belong to the tetragonal aThSi 2 -type, the binary GdSi 2Àx crystallizes in its own aGd 2 Si 3 -type (Imma) [24]. The latter is simply a slight orthorhombic distortion of the tetragonal archetype, which is largely due to the decrease in atomic size of the rare-earth metals when moving across the lanthanide series.…”

The Plutonium-Silicon System

“…These lines were indexed on the basis of body-centered ortharhambic unit cells having dimensions as shawn in Table 1. It is expected that the orthorhambic structure will prove to be isostructural with the orthorhambic rare-earth "disilicides" reported by Perri et al· (12) As shown in Table 1, the b/a ratio goes from 0.992 at 64.5 a/0 silicon to unity at 66.7 a/0 silicon. However, the microstructures of these alloys showed that only the 64.5 a/0 silicon alloy was single phase K. The rest .…”

“…The structural type is that of FeB, and the space (12) group is Fbrmt. There are 4 formula units in the unit cell, which has the dimensions a = 5.727 a 0.005, b = 7.933 f 0.003 and c = 3.847 k 0.001 A.…”