On the effect of Ga and In substitutions in the Ca₁₁Bi₁₀and Yb₁₁Bi₁₀bismuthides crystallizing in the tetragonal Ho₁₁Ge₁₀structure type

Abstract

The Ga- and In-substituted bismuthides CaGaBi, CaInBi, YbGaBi, and YbInBi (x < 2) can be readily synthesized employing molten Ga or In metals as fluxes. They crystallize in the tetragonal space group I4/mmm and adopt the HoGe structure type (Pearson code tI84; Wyckoff sequence n2 m j h2 e2 d). The structural response to the substitution of Bi with smaller and electron-poorer In or Ga has been studied by single-crystal X-ray diffraction methods for the case of CaInBi [x = 1.73 (2); octabismuth undecacalcium diindium]. The refinements show that the In atoms substitute Bi only at the 8h site. The refined interatomic distances show an unconventional - for this structure type - bond-length distribution within the anionic sublattice. The latter can be viewed as consisting of isolated Bi anions and [InBi] clusters for the idealized CaInBi model. Formal electron counting and first-principle calculations show that the peculiar bonding in this compound drives the system toward an electron-precise state, thereby stabilizing the observed bond-length pattern.

Undistorted linear Bi chains with hypervalent bonding in La3TiBi5 from single-crystal X-ray diffraction

“…The resulting Bi2-Bi2 interaction is of bonding type, as can be seen from the integral COHP at the Fermi level, though the bonding is underoptimized. Such a bonding picture appears to be typical for hypervalent interactions in metal pnictides, as follows from first-principles calculations for polyanionic units in antimonides and bismuthides (Papoian & Hoffmann, 2000;Ovchinnikov & Bobev, 2018a).…”

“…As a result, undistorted one-dimensional chains are not observed in nitrides, but can be found for the heavier congeners, provided that packing effects or other stabilizing factors are present. Since the occurrence of structural distortions directly affects the anisotropy of the chemical bonding, the electronic stability of the anionic sublattice is related to the physical properties and may have implications for the development of thermoelectric materials or superconductors (Ovchinnikov & Bobev, 2018a;Tamura et al, 2017).…”

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

“…Both interactions are slightly underoptimized owing to population of the antibonding states just below E F . Such an electronic pattern is typical for electron-rich (hypervalent) bonding. ,, For the Bi–Bi pairs in the zigzag chains, a localized region of antibonding character is situated in the energy window of 0.7 eV < E – E F < 1.9 eV. It can be foreseen that electron doping would eventually destabilize the Bi–Bi bonding, which could lead to structural distortions or decomposition into competing phases.…”

“…When possible, the application of fluxes containing exclusively those elements that constitute the targeted crystals is beneficial because it allows one to avoid the presence of foreign elements in the product. In this way, many compounds of low-melting metals, e.g., gallium, indium, and tin, can be produced using the respective metal as a reactive flux. ,− …”

p-Type Double Doping and the Diamond-like Morphology Shift of the Zintl Phase Thermoelectric Materials: The Ca11–xAxSb10–yGez (A = Na, Li; 0.06(3) ≤ x ≤ 0.17(5), 0.19(1) ≤ y ≤ 0.55(1), 0.13(1) ≤ z ≤ 0.22(1)) System

“…During the last several years, our group has thoroughly investigated the Zintl phase A 11 M 10 (A = alkali-/alkaline-earth/rare-earth metals; M = tetrels, pnictogens) series to exploit its intrinsic characteristics as TE materials based on its exceptionally low thermal conductivity from the complex Ho 11 Ge 10 -type phase and the particular electronic transport property from the poor-metallic/semiconducting behaviors. − Some of our previous results for this series include the RE 11 ­Ge 4 In 6– x M x (RE = La, Ce; M = Li, Ge; x = 1, 1.96), Ce 11 ­Ge 3.73(2) In 6.27 , Ca 11– x Yb x ­Sb 10– y ­Ge z (0 ≤ x ≤ 9; 0 ≤ y ≤ 3; 0 ≤ z ≤ 3), and Eu 11– x K x Bi 10– y Sn y ( x = 0, 0.26; y = 0.86, 1.93) systems. Very recently, we even tried to apply the n -type dopants for this series and successfully synthesized two novel Zintl phase systems: the Ca 11– x RE x ­Sb 10– y (RE = La, Ce, Nd, Sm; 0.18(4) ≤ x ≤ 0.43(2), 0.14(1) ≤ y ≤ 0.41(1)) and Ca 11– x RE x ­Sb 10– y (RE = Tb, Dy, Ho, Er, Tm; 0.35(6) ≤ x ≤ 0.41(4), 0.27(1) ≤ y ≤ 0.51(2)) systems.…”