Synthesis, Crystal, and Electronic Structure of Ba₃Sb₂Q₇ (Q = S, Se)

Abstract

Abstract. Two new barium antimony chalcogenides, Ba 3 Sb 2 S 7 and Ba 3 Sb 2 Se 7 , were synthesized from elements by high-temperature solidstate reactions. The crystal structures were determined by means of single-crystal X-ray diffraction. Both compounds are isostructural and crystallize in a new structure type in the monoclinic space group C2/c (No. = 15) with unit cell parameters of a = 18.305 (2)

Synthesis, crystal and electronic structure, and optical properties of two new chalcogenide-iodides: Ba3Q4I2 (Q = S, Se)

“…1B and C). In Ba 3 S 4 I 2 , the S-S distances are 2.107(2) and 2.121(2) Å, which are close to the sum of the corresponding Pauling radius of S (1.05 Å) 23 and comparable to S-S distances in barium polysulfides, such as BaS 2 (2.12 Å), 24 BaS 3 (2.08 Å), 25 Ba 3 Sb 2 S 7 (2.09 Å), 26 and Sr 6 Sb 6 S 17 (2.09 Å). 1B and D).…”

“…Each iodine atom is surrounded by five Ba atoms forming a distorted trigonal bipyramid (blue polyhedra in Fig. 27 The Ba-S distances in Ba 3 S 4 I 2 (3.11-3.28 Å) are similar to the distances found in Ba 3 Sb 2 S 7 (3.14-3.35 Å), 26 BaSb 2 S 4 (3.13-3.35 Å), 28 and Ba 4 Fe 2 S 4 I 5 (3.20-3.30 Å). Both types of Ba atoms are surrounded by a distorted capped trigonal prisms composed of eight or nine atoms: Ba1 is surrounded by six sulfur atoms and three I atoms and Ba2 is coordinated to four sulfur atoms and four I atoms (Fig.…”

Synthesis, crystal structure, and thermoelectric properties of two new barium antimony selenides: Ba2Sb2Se5and Ba6Sb7Se16.11

“…We believe that such local disorder has a dramatic impact on the thermal conductivity of this compound (vide infra). Assuming +2, +3, and -2 formal oxidation states for Ba, Sb, and Se respectively, the electron-balanced composition is (Ba 2+ ) 6 (Sb 3+ ) 7 (Se 2-) 16 (Sb 4 S 9 ) 6one-dimensional slabs, [17] which are similar to the one-dimensional Sb-Se fragments found in Ba 2 Sb 2 Se 5 . Thus, each of these Se atoms is two-coordinated.…”

“…The splitting of the Se positions leads to the alteration of the Sb coordination as shown in Figure 2 using the example of the ∞ 1 (Sb 4 Se 9 ) 6fragment that is present in the crystal structure of antimony is reduced to an average coordination of three Se atoms. [16] In the flat ∞ 1 (Ba 2 Se) 2+ fragment each Se atom is surrounded by a square of Ba atoms. While the coordination numbers of one and five are extremes with low probabilities of occurring, local Sb coordination numbers of two, three, and four Se atoms are more probable.…”

“…[15] We have recently reported another compound, Ba 3 Sb 2 Se 7 , containing isolated SbSe 3 and SbSe 4 fragments in the crystal structure. [16] Herein we describe two new compounds, Ba 2 Sb 2 Se 5 and Ba 6 Sb 7 Se 16.11 , which crystallize in new structure types. In their crystal structures, one-(Ba 2 Sb 2 Se 5 ) and two-dimensional (Ba 6 Sb 7 Se 16.11 ) Sb-Se fragments alternate with one-dimensional Ba-Se bands and additional Ba atoms.…”