Y₃MnAu₅: Three Distinctive d-Metal Functions in an Intergrown Cluster Phase

Abstract

The new Y(3)MnAu(5) intermetallic phase is obtained from the arc-melted elements in virtually quantitative yields after annealing at 1000 °C for ~3 d. Its remarkable structure [rhombohedral, R3, Z = 6; a = 8.489(1) Å, c = 18.144(2) Å] consists of a 2:1 cubic-close-packed intergrowth between edge-shared Mn-centered Au rhombohedra (Mn@Au(8)) with gold-centered antiprismatic (Au@Y(6)) clusters via a common gold network. Magnetic susceptibility (χ) data for Y(3)MnAu(5) were fitted by a Curie-Weiss law. The Curie constant indicates a large effective moment corresponding to nearly localized Mn spins S = 5/2, and the Weiss temperature demonstrates the dominance of ferromagnetic (FM) interactions. An antiferromagnetic (AFM) transition at T(N) = 75 K and a possible spin reorientation transition at 65 K were observed. Analysis of the χ data for T < T(N) suggests a planar noncollinear helical AFM structure that arises from competing AFM interactions between FM-aligned layers of spins in the ab-plane with a turn angle of 69° between the spins along the helix c-axis. A magnetic field-induced spin flop transition is observed below T(N). Spin-polarized LMTO-LSDA calculations indicate an ~2 eV splitting of the Mn 3d states and a metallic ground state, and their COHP analyses demonstrate that ~81% of the total Hamilton populations originate from heteroatomic polar Y-Au and Mn-Au bonding. The Mn 3d, Y 4d, and Au 5d characteristics are remarkably diverse: localized and magnetically polarized for Mn; reducing and cationic for Y; and relativistically strongly bonded and oxidizing for Au, bonding of the latter two being broadly delocalized.

Hexagonal-Diamond-like Gold Lattices, Ba and (Au,T)3 Interstitials, and Delocalized Bonding in a Family of Intermetallic Phases Ba2Au6(Au,T)3 (T = Zn, Cd, Ga, In, or Sn)

“…For example, secondary efforts were necessary in the recent discoveries of the novel Ca 4 Au 10 In 3 14 and Y 3 MnAu 5 . 26 The single-crystal refinements (Experimental Section) also established that the Wyckoff 18e sites that define the triangular units are always occupied by Au/T mixtures and never by pure Au or pure T, whereas the 36f site that defines the entire host lattice is fully occupied by Au atoms. Therefore, the phase width of each 2−6−3 phase is related to only the range of Au and T proportions at the 18e site.…”

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

“…Based on Allred's electronegativities, 36 in which Au (2.54) is more electronegative than Sn (1.96) and Gd (1.20), respectively, less electron withdrawal can be expected from the Gd atoms guiding to a rather polar (Au-Gd) interaction, which is well recognized for other rare-earth late transition metal compounds. 51,52 Experimental Syntheses Starting materials for the preparations of R 3 Au 7 Sn 3 (R = Y, Gd) were fillings of Y and Gd produced from high-purity ingots (Materials Preparation Center of the Ames Laboratory, 53 99.9+ wt%), Sn ingots (Alfa Aesar, 99.999 wt%) and Au pieces (BASF, 99.999 wt%). Single crystals of both compounds were obtained from reaction mixtures of 260-400 mg total, which were loaded in pre-cleaned, on-side Ar-arc welded tantalum containers inside an Ar-filled glove box (O 2 o 0.1 ppm, H 2 O o 0.1 ppm).…”

Magnetocaloric Behavior in Ternary Europium Indides EuT5In: Probing the Design Capability of First-Principles-Based Methods on the Multifaceted Magnetic Materials

“…On the other hand, investigation of the Eu–Au–In system points to the presence of a tetragonal, YbMo 2 Al 4 -type derived disordered crystal structure for EuAu 5 In, which has the same valence electron count as tentative EuCu 5 In, yet one has to keep in mind that the influence of relativistic effects increases considerably from copper to its heavier homologue gold . Due to the relativistic effects, , gold exhibits substantial 6s–5d orbital mixings in its bonding, which were also encountered in the bonding analyses of different gold-rich complex intermetallic compounds. − The exploration of the Au-rich areas for the ternary system Eu–Au–In was further encouraged by the previous discoveries of the diamond-like Au networks in Ae­(Au,M) 7 and Ae 2 (Au,M) 9 (Ae = Sr, Ba, Eu; M = Al, Zn, Ga, Cd, In, Sn; not all combinations), − the indide EuAu 17.7 In 4.3 , and the stannides R 3 Au 7 Sn 3 (R = Y, Gd) pointing to a large potential for the presence of unknown ternary Au-rich materials with rare-earth and post-transition elements.…”