Bismuth as a Reactive Solvent in the Synthesis of Multicomponent Transition-Metal-Bearing Bismuthides

Flux Growth, Crystal Structures, and Electronic Properties of the Ternary Intermetallic Compounds Ca3Pd4Bi8 and Ca3Pt4Bi8

Reaction of the elements yielded Ca₃Pt₄Bi₈ and CaPtBi, which are, to the best of our knowledge, the first reported ternary Ca–Pt–Bi compounds. The compounds crystallize isostructural to the Pd analogs Ca₃Pd₄Bi₈ (own structure type) and CaPdBi (TiNiSi structure type), respectively. Employing a multistep temperature treatment allows for the growth of mm-sized single crystals of Ca₃Pd₄Bi₈ and Ca₃Pt₄Bi₈ from a Bi self-flux. Their crystal structures can be visualized as consisting of a three-dimensional extended polyanion [M₄Bi₈]^6– (M = Pd, Pt), composed of interlinked M–Bi chains propagating along the c direction, and Ca²⁺ cations residing in one-dimensional channels between the chains. First-principles calculations reveal quasi-one-dimensional electronic behavior with reduced effective electron masses along [001]. Bader analysis points to a strong anionic character of the M species (M = Pd, Pt) in Ca₃M₄Bi₈. Thus, it is more appropriate to address the compounds Ca₃Pd₄Bi₈ and Ca₃Pt₄Bi₈ as a palladide and platinide, respectively. Magnetization measurements indicate diamagnetic behavior with no indications for superconductivity down to 2 K. Electrical resistivity data are consistent with metallic behavior and suggest predominant electron–phonon scattering.

Reaction of the elements yielded Ca₃Pt₄Bi₈ and CaPtBi, which are, to the best of our knowledge, the first reported ternary Ca−Pt−Bi compounds.

Electronic stabilization by occupational disorder in the ternary bismuthide Li3-x-yInxBi (x ≃ 0.14, y ≃ 0.29)

A ternary derivative of Li₃Bi with the composition Li_3-x-yIn_xBi (x ≃ 0.14, y ≃ 0.29) was produced by a mixed In+Bi flux approach. The crystal structure adopts the space group Fd-3m (No. 227), with a = 13.337 (4) Å, and can be viewed as a 2 × 2 × 2 superstructure of the parent Li₃Bi phase, resulting from a partial ordering of Li and In in the tetrahedral voids of the Bi fcc packing. In addition to the Li/In substitutional disorder, partial occupation of some Li sites is observed. The Li deficiency develops to reduce the total electron count in the system, counteracting thereby the electron doping introduced by the In substitution. First-principles calculations confirm the electronic rationale of the observed disorder.

Exploration of Multi-Component Vanadium and Titanium Pnictides Using Flux Growth and Conventional High-Temperature Methods

The flux growth method was successfully employed to synthesize millimeter-sized single crystals of the ternary barium vanadium pnictides Ba₅V₁₂As_19+x (x ≈ 0.02) and Ba₅V₁₂Sb_19+x (x ≈ 0.36), using molten Pb and Sb, respectively. Both compositions crystallize in space group P 4 ¯ 3m and adopt a structure similar to those of the barium titanium pnictides Ba₅Ti₁₂ Pn _19+x (Pn = Sb, Bi), yet with a subtly different disorder, involving the pnictogen and barium atoms. Attempts to obtain an arsenide analog of Ba₅Ti₁₂ Pn _19+x using a Pb flux technique yielded binary arsenides. High-temperature treatment of the elements Ba, Ti, and As in Nb or Ta tubes resulted in side reactions with the crucible materials and produced two isostructural compositions Ba₈Ti_13-x M _x As₂₁ (M = Nb, Ta; x ≈ 4), representing a new structure type. The latter structure displays fcc-type metal clusters comprised of statistically distributed Ti and M atoms (M = Nb, Ta) with multi-center and two-center bonding within the clusters, as suggested by our first-principle calculations.