Scientists discover nickel compound with rare diamond-like structure
Researchers have identified a new intermetallic compound where nickel atoms arrange in a diamond-like lattice—a structural pattern previously seen only in gold-based materials. The finding could open doors for developing new catalysts, magnets, or semiconductors with improved properties for industrial applications.
Originaltitel: La-Ni-Si: A Gold Mine with a Diamond
<p>The La-poor part of the ternary La–Ni–Si system has been explored leading to the discovery and structural characterization of four new polar intermetallic compounds. LaNi<sub>5</sub>Si<sub>2</sub> [BaAu<sub>5</sub>Ga<sub>2</sub> type, <em>oP</em>64, space group <em>Pnma</em>, <em>a</em> = 7.8223(7) Å, <em>b</em> = 6.3894(6) Å, <em>c</em> = 17.843(2) Å, <em>V</em> = 891.8(2) Å<sup>3</sup>, <em>Z</em> = 8] features a diamond (lonsdaleite)-like homoatomic Ni framework and is the first Ni representative of a larger family of compounds typically formed by aurides. La<sub>2</sub>Ni<sub>8</sub>Si<sub>3</sub> [Eu<sub>2</sub>Ni<sub>8</sub>Si<sub>3</sub> type, <em>tP</em>52, <em>P</em>4<sub>2</sub>/<em>nmc</em>, <em>a</em> = 10.0278(3) Å, <em>c</em> = 7.5047(4) Å, <em>V</em> = 754.65(6) Å<sup>3</sup>, <em>Z</em> = 4] is characterized by homoatomic Ni<sub>4</sub> tetrahedra and rectangles. LaNi<sub>5</sub>Si<sub>3</sub> [SrNi<sub>5</sub>P<sub>3</sub> type, <em>oS</em>36, <em>Cmcm</em>, <em>a</em> = 3.722(2) Å, <em>b</em> = 11.759(5) Å, <em>c</em> = 11.622(3) Å, <em>V</em> = 508.7(3) Å<sup>3</sup>, <em>Z</em> = 4] is governed by extensive heteroatomic bonding and characterized by homopolyhedral packing. La<sub>3</sub>Ni<sub>4</sub>Si<sub>2</sub> [Ce<sub>3</sub>Ni<sub>4</sub>Si<sub>2</sub> type, <em>mC</em>36, <em>C</em>2/<em>c</em>, <em>a</em> = 15.819(1) Å, <em>b</em> = 6.0068(5) Å, <em>c</em> = 7.4918(6) Å, β = 103.163(5)°, <em>V</em> = 693.17(10) Å<sup>3</sup>, <em>Z</em> = 4] is a new member of homologous series that includes La<sub>3</sub>Ni<sub>3</sub>Si<sub>2</sub> and La<sub>3</sub>Ni<sub>3.5</sub>Si<sub>2</sub>. We conclude that the similar radii and electronegativities of Ni and Si are the reason for the incredible diversity of compositions and structures in this system.</p>