BaSbTe₃ und BaBiSe₃ Verbindungen mit BiSe-bzw. SbTe-Schichtverbänden / BaSbTe₃ and BaBiSe₃ Compounds with BiSe-or SbTe-Layer Structures, Respectively

Abstract

<jats:title>Abstract</jats:title><jats:p> The new compounds BaBiSe<jats:sub>3</jats:sub> and BaSbTe<jats:sub>3</jats:sub> crystallize in the orthorhombic system, space group P2<jats:sub>1</jats:sub>2<jats:sub>1</jats:sub>2<jats:sub>1</jats:sub> with </jats:p><jats:p>BaBiSe<jats:sub>3</jats:sub>: a = 1724 ± 2 pm, b = 1600 ± 2 pm, c = 437.0 ± 0.5 pm; </jats:p><jats:p>BaSbTe<jats:sub>3</jats:sub>: a = 1809 ± 2 pm, b = 1694 ± 2 pm, c = 463.5 ± 0.4 pm. </jats:p><jats:p>BiSe<jats:sub>6</jats:sub><jats:sup>-</jats:sup> or SbTe<jats:sub>6</jats:sub><jats:sup>-</jats:sup> octahedra, resp., are connected by common edges to fourfold strings. These are bound by additional chalcogen atoms to sheets, between which the Ba ions are located. </jats:p>

Different clusters within the Ba4M4−xA2Te9 (M=Cu, Ag, Au; A=Si, Ge) series: Crystal structures and transport properties

“…In all these cases, the Ba atoms are surrounded by eight Te atoms, with distances in the range of 3.50-3.68 Å for Ba 4 Cu 3.75 Si 2 Te 9 , 3.49-3.77 Å for Ba 4 Ag 3.97 Si 2 Te 9 and 3.50-3.81 Å for Ba 4 Au 3.69 Ge 2 Te 9 . These distances are comparable to the Ba-Te bonds in other Ba tellurides, such as BaSbTe 3 (3.41-3.89 Å) [23], Ba 2 SnTe 5 (3.44-3.84 Å) [24], and Ba 3 Cu 14 Te 12 (3.47-3.84 Å) [6], which have ninefold coordinated Ba atoms.…”

Oligomerization Versus Polymerization of Texn- in the Polytelluride Compound BaBiTe3. Structural Characterization, Electronic Structure, and Thermoelectric Properties

“…The Coulombic interactions between Ba 2+ and the nine Te atoms in its coordination polyhedron seem to be important in stabilizing this structure type. We point out that BaBiTe 3 , BaBiSe 3 , and BaSbTe 3 are all isostructural, , while the strontium compounds , are not, probably because a smaller cation such as Sr 2+ cannot accommodate nine Te atoms in its immediate coordination environment. The size of the alkaline earth metal appears to play an important role in determining the structure type of ternary Group 15 chalcogenide compounds.…”

“…The average Bi−Te bond length is 3.196 Å and the average Te−Bi−Te angles (two types) are 89.88° and 172.48°. Although the compound is isomorphous to BaSbTe 3 , there are notable differences in the degree of structural distortion around the metal atoms from the ideal octahedral motif, with the Sb octahedra being significantly more distorted than those of Bi. This distortion is due to the tendency of the s 2 lone electron pair to stereochemically express itself and is consistent with its greater tendency to do so in Sb than in Bi.…”

“…Synthesis and Thermal Analysis. The known BaSbQ 3 (Q = Se, Te) and BaBiSe 3 were synthesized by direct combination of a mixture of elements or alkaline earth metal acetate with Group 15 metal and elemental chalcogen …”

Thermoelectric properties of the new tellurides SrSc2Te4 and BaSc2Te4 in comparison to BaY2Te4

“…The AeTe distances are inconspicuous, ranging from 3.37 Å to 3.61 Å in SrSc 2 Te 4 and from 3.46 Å to 3.60 Å in BaSc 2 Te 4 ( Table 3). Comparable distances occur in SrTe (NaCl type, six SreTe bonds per Sr atom of 3.3 Å [20]) and isostructural BaTe (3.42 Å [21]), as well as in the ternaries SrGa 2 Te 4 (eight SreTe bonds per Sr atom between 3.45 Å and 3.47 Å [22]), BaSbTe 3 (nine BaeTe bonds per Ba atom of 3.41e3.89 Å [23]) and Ba 2 SnTe 5 (again nine bonds, 3.44e3.84 Å [24]). …”