Bell‐Like [Ga₅] Clusters in Eu₃Li_5+xGa_5–x (x = 0.15)

Abstract

Keywords: Cluster compounds / Gallium / Intermetallic phases / Electronic density of statesThe new ternary gallide Eu 3 Li 5+x Ga 5-x was synthesized from its constituent elements that were heated at 900°C and then subsequently annealed at 300°C for 10 months. The crystal structure was established from single-crystal diffraction data. A new type of discrete gallium cluster was found in Eu 3 Li 5+x Ga 5-x , namely a bell-like [Ga 5 ] unit with one single-, one four-and three three-bonded atoms. On the basis of its

Electronic stabilization by occupational disorder in the ternary bismuthide Li3–x–y In x Bi (x ≃ 0.14, y ≃ 0.29)

“…Nevertheless, as we will demonstrate below, using first-principles calculations, the model with mixed occupation is the more likely choice due to electronic structure considerations. Additionally, we must also note that mutual substitutions between Li and some p-block elements, such as Ga, In, and Sn, have been observed frequently in various types of intermetallic compounds, including several bismuthides (Fedorchuk et al, 2011;Smetana et al, 2010;Ovchinnikov & Bobev, 2019b,c;You & Bobev, 2010;Sreeraj et al, 2005;Ojwang & Bobev, 2018). The overall occupation factor for the discussed site was set to 1, resulting in the refined In/Li ratio of 0.577 (8):0.423.…”

Bell–like [Ga5] clusters in Sr3Li5Ga5: synthesis, crystal structure and bonding analysis.

“…x Ga 5À x . [1] As the refinement of the Ga positions occupancies yielded values equal to one within few e.s.d. (Ga1: 0.999(3); Ga2: 0.987(4); Ga3: 0.978( 4)).…”

“…Based on the size difference between Eu and Sr (ionic radii: r(Eu 2 + ) = 1.12 Å, r(Sr 2 + ) = 1.27 Å and atomic radii: r(Eu): = 2.042 Å, r-(Sr) = 2.15 Å) [13] an increase of the unit cell parameters is to be expected. A comparison of Sr 3 Li 5 Ga 5 with Eu 3 Li 5 + x Ga 5À x (R3m; a = 9.4859(5) Å, c = 21.882(2) Å, V = 1705.2(3) Å 3 ), [1] reveals that the introduction of strontium instead of europium, indeed, leads to an enlargement of the cell parameters to a = 9.6040(5) Å and c = 22.061(1) Å. The unit cell volume V is therefore also increased by 57 Å 3 to 1762.2(3) Å 3 .…”

“…The new strontium compound is isotypic to the europium analog Eu 3 Li 5 + x Ga 5À x . [1] The suggested electron counting for the latter [ [15] interpretation of the bell-like [Ga 5 ] unit. On the other hand, the pyramidal unit [Ga 5 ] in Ba 3 LiGa 5 was proven by detailed bonding analysis to be a nido Wade anion.…”

“…With the discovery of Eu 3 Li 5 + x Ga 5À x (x = 0.15), [1] a new type of gallium arrangement, the bell-like cluster, was introduced into the series of known isolated gallium clusters in intermetallic compounds. [2] Among these, ranging from dumbbells in Eu 3 Ga 2 [3] to tetrahedra and square pyramids in Ba 8 Ga 7 [4] and U 3 Ga 5 [5] respectively, the bell-like [Ga 5 ] unit is exceptional, as it is the only known gallium cluster to be nonconvex.…”