Revisiting the Zintl–Klemm Concept: A₂AuBi (A = Li or Na)

Abstract

Keywords: Solid-state structures / Diamond network / Zintl phases / Zintl-Klemm formalism / Gold / Bismuth / Thallium / Alkali metals / Electronic structure / Density functional calculations Alkali metal gold bismuthides, A 2 AuBi, are isoelectronic with alkali metal thallides, ATl = A 2 TlTl, and yet Na 2 AuBi adopts an orthorhombic structure with a 1-D zigzag "ribbon" structural motif rather than the cubic double diamond structure type of NaTl as well as Li 2 AuBi. Using first principles quantum mechanical calculations applied to A 2 AuBi, hypothetical "A 2 HgPb," and A 2 TlTl, and comprehensively decomposing the total energies into metallicity, ionicity, and covalency components to establish parallels with the qualitative ZintlKlemm formalism, the factors determining the relative stability between the zigzag "ribbon" and the diamond network are examined. An interplay between volume-dependent en-

Electronic fitness function for screening semiconductors as thermoelectric materials

“…71 Based on the EFF, two alkali metal Zintl phases Na 2 AuBi and KSnSb are identified to have particularly favorable band complexity compared with the other ternary compounds including selected HHs and FHs. Na 2 AuBi has been identified as a semiconductor theoretically, 72 but is little-studied as a TE material. It crystallizes with an orthorhombic Cmcm structure (Fig.…”

Synthesis, Crystal and Electronic Structure of the Titanium Bismuthides Sr5Ti12Bi19+x, Ba5Ti12Bi19+x, and Sr5–δEuδTi12Bi19+x (x ≈ 0.5–1.0; δ ≈ 2.4, 4.0)

“…Transition metal pnictides adopt a large variety of crystal structures, whereby extended metal–metal bonding and polyatomic pnictogen species, such as isolated olygomers, chains, and/or two‐dimensional nets, are recurring motifs (the terms pnictogen and pnictides refer to the heavier N congeners and their compounds with other metals). Such diverse bonding patterns often come together with complex atomic arrangements.…”

Novel gold intermetallics with unique properties and bonding patterns

“…However, neither are exceptionally short within the literature.11,60 And more generally, atomic R-Au, Au-Au, and Au-M distances within all other samples appear within expected values from literature from their respective fields of intermetallics. [61][62][63] SEM images with EDS analysis of La-Au-Bi, Pr-Au-Sb, Nd-Au-Ga, Sm-Au-Bi, and Lu-Au-Ga samples (Figure A9andTable A4respectively) are in agreement with atomic compositions predicted from refinements of single crystals, and support claims that samples in this report are in fact ternary representatives, and not simply the reported binary phases. Atomic phase width reported for the Pr14Au51 binary phase (as well as within a ternary representative: Pr14(Au, Sn)51) allows for slightly more gold-rich compositions than expected from the line composition.48 EDS elemental values from the report on the R3Au9Pn structure describe a secondary phase labeled as "Tb14(Au, Sb)51," which are also within 1 at% of the composition designated for the Tb-Au-Sb sample by the single crystal refinement data of this work.…”