New cubic cluster phases in the Mg–Ni–Ga system

Abstract

<jats:p>The crystal structure of new Mg<jats:sub>9</jats:sub>Ni<jats:sub>6</jats:sub>Ga<jats:sub>14</jats:sub> and Mg<jats:sub>3</jats:sub>Ni<jats:sub>2</jats:sub>Ga compounds were investigated by single-crystal diffraction. Both structures can be described as three-core-shell cluster compounds. In the Mg<jats:sub>6</jats:sub>Ni<jats:sub>9</jats:sub>Ga<jats:sub>14</jats:sub> structure, the [Ni<jats:sub>6</jats:sub>Ga<jats:sub>6</jats:sub>] icosahedron is encapsulated within the [Mg<jats:sub>20</jats:sub>] dodecahedron, which is again encapsulated within a [Ni<jats:sub>18</jats:sub>Ga<jats:sub>42</jats:sub>] fullerene-like truncated icosahedron, thus the three core–shell cluster [Ni<jats:sub>6</jats:sub>Ga<jats:sub>6</jats:sub>@Mg<jats:sub>20</jats:sub>@Ni<jats:sub>18</jats:sub>Ga<jats:sub>42</jats:sub>] results. In the Mg<jats:sub>3</jats:sub>Ni<jats:sub>2</jats:sub>Ga structure, the [Mg<jats:sub>6</jats:sub>] octahedron is encapsulated within the [Ni<jats:sub>12</jats:sub>Ga<jats:sub>6</jats:sub>] flattened icosahedron in vertices of which there are 12 nickel atoms, and six lateral edges are centered by gallium atoms, which in turn is encapsulated within a [Mg<jats:sub>36</jats:sub>] pseudo-rhombicuboctahedron with 12 additional atoms centering the lateral faces; thus for Mg<jats:sub>3</jats:sub>Ni<jats:sub>2</jats:sub>Ga the three-shell cluster is [Mg<jats:sub>6</jats:sub>@Ni<jats:sub>12</jats:sub>Ga<jats:sub>6</jats:sub>@Mg<jats:sub>36</jats:sub>].</jats:p>

MgMn4Ga18: a novel three-shell gallium cluster structure

“…3. MgMn 4 Ga 18 can be attributed to the cluster intermetallics, among which we have described such magnesium-containing intermetallic phases as Li 20 Mg 6 Cu 13 Al 42 (Pavlyuk et al, 2019), Mg 9 Ni 6 Ga 14 and Mg 3 Ni 2 Ga (Pavlyuk et al, 2020). These structures are described as three-shell icosahedral clusters.…”

“…Ternary systems Mg-T-Ga (where T = Mn, Fe, Co and Ni) have not yet been studied in the full concentration range; only some intermetallic compounds have been studied by our group. Most of them are from the Mg-Ni-Ga and Mg-Co-Ga systems, in particular, Mg 3 Co 2 Ga 7 (Pavlyuk et al, 2007), MgCoGa 2 (Pavlyuk et al, 2020), MgCo 2 Ga 5 and MgNi 2 Ga 5 (Pavlyuk et al, 2020a), and Mg 9 Ni 6 Ga 14 and Mg 3 Ni 2 Ga (Pavlyuk et al, 2020b).…”