Gold-rich R₃Au₇Sn₃: establishing the interdependence between electronic features and physical properties

Abstract

Two new polar intermetallic compounds Y3Au7Sn3 (I) and Gd3Au7Sn3 (II) have been synthesized and their\ud structures have been determined by single crystal X-ray diffraction (P63/m; Z = 2, a = 8.148(1)/8.185(3),\ud and c = 9.394(2)/9.415(3) for I/II, respectively). They can formally be assigned to the Cu10Sn3 type\ud and consist of parallel slabs of Sn centered, edge-sharing trigonal Au6 antiprisms connected through\ud R3 (R = Y, Gd) triangles. Additional Au atoms reside in the centres of trigonal Au6 prisms forming\ud Au@Au6 clusters with Au–Au distances of 2.906–2.960 Å, while the R–R contacts in the R3 groups are\ud considerably larger than the sums of their metallic radii. These exclusive structural arrangements provide\ud alluring systems to study the synergism between strongly correlated systems, particularly, those in the\ud structure of (II), and extensive polar intermetallic contacts, which has been inspected by measurements\ud of the magnetic properties, heat capacities and electrical conductivities of both compounds. Gd3Au7Sn3\ud shows an antiferromagnetic ordering at 13 K, while Y3Au7Sn3 is a Pauli paramagnet and a downward\ud curvature in its electrical resistivity at about 1.9 K points to a superconducting transition. DFT-based\ud band structure calculations on R3Au7Sn3 (R = Y, Gd) account for the results of the conductivity measurements\ud and different spin ordering models of (II) provide conclusive hints about its magnetic structure.\ud Chemical bonding analyses of both compounds indicate that the vast majority of bonding originates\ud from the heteroatomic Au–Gd and Au–Sn interactions, while homoatomic Au–Au bonding is evident\ud within the Au@Au6 cluster

An Obscured or Nonexistent Binary Intermetallic, Co7Pr17, Its Existent Neighbor Co2Pr5, and Two New Ternaries in the System Co/Sn/Pr, CoSn3Pr1–x, and Co2–xSn7Pr3

“…Å. This picture is a specific anti-type analogy to the Au-rich rare earth stannides Au7Sn3R3, 64,65 where all T−Sn contacts are restricted to {SnT6} trigonal antiprisms. The corresponding −COHP plot shows that these interactions are significantly populated at lower energies but are rather nonbonding at the EF, while the addition of more electrons shifts them into strongly and Sn-Pr (37.4%) bonding interactions are dominant in CoSn3Pr, with a small contribution from Co-Pr interactions, subject to the long distances between these atoms (3.390 Å).…”

Gold Polar Intermetallics: Structural Versatility through Exclusive Bonding Motifs

“…Beside QCs and ACs, the systems with Au, triels, and light alkali metals (mostly Na) contain compounds exhibiting structural components with local fivefold symmetry icosahedra and polyicosahedral clusters, pentagonal bipyramids, and prisms (Table S3). Multiply endohedral clusters observed in K 34 Au 9 In 96 , Na 17 Au 6 Ga 47 , and Na 1.0 Au 0.2 Ga 1.8 ideally follow the first three shells of the classical Bergman-type sequence. The next shell, the M 60 buckyball-like polyhedron, surprisingly allows inclusion of the formal cation, Na.…”

Revealing the Bonding Nature in an ALnZnTe3-Type Alkaline-Metal (A) Lanthanide (Ln) Zinc Telluride by Means of Experimental and Quantum-Chemical Techniques

“…A 24 × 6 × 8 k-points set was used to sample the first Brillouin zone, and all computations were considered to be converged, as the energy difference between two iterative steps fell below 10 −8 eV/cell (and 10 −6 eV/cell) for the electronic (and ionic) relaxations. The dysprosium 4f states were treated as core-like in all computations-an approach that can be adopted because the valence electrons residing in the 4f states are typically localized and, hence, barely contribute to overall bonding in a given solid-state material [47][48][49].…”