Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba3ThSe3(Se2)2

Abstract

Synthesis, crystal structure, optical, and electronic study of the new ternary thorium selenide Ba 3 ThSe 3 (Se 2 ) 2 Journal of Solid State Chemistry, http://dx.Abstract The compound Ba 3 ThSe 3 (Se 2 ) 2 has been synthesized by solid-state methods at 1173 K. Its crystal structure features one dimensional chains of 1 ∞ [Th(Se) 3 (Se 2 ) 2 6− ] separated by Ba 2+ cations. Each Th atom in these chains is coordinated to two Se−Se single-bonded pairs and four Se atoms to give rise to a pseudoocthedral geometry around Th. The Th−Se distances are consistent with Th 4+ and hence charge balance of Ba 3 ThSe 3 (Se 2 ) 2 is achieved as 3 × Ba 2+ , 1 × Th 4+ , 3 × Se 2− , and 2 × Se 2 2−. From optical measurements the band gap of Ba 3 ThSe 3 (Se 2 ) 2 is 1.96(2) eV.DFT calculations indicate that the compound is a semiconductor.

Synthesis and Crystal Structure of Cs2U2(P2Se9)(Se2)2

“…This structure of Cs 2 U 2 (P 2 Se 9 )(Se 2 ) 2 also contains two distinct Se 2 2– species having distances of 2.403(1) and 2.409(1) Å, in good agreement with the corresponding distances in Ba 8 PdU 2 Se 12 (Se 2 ) 2 [2.392(1) and 2.407(1) Å], Cs 2 Th 2 (P 2 Se 9 )(Se 2 ) 2 [2.404(2) and 2.409(2) Å], and Rb 2 U 2 (P 2 Se 9 )(Se 2 ) 2 [2.411(4) and 2.413(4) Å] . These distances are slightly longer than the single Se bonds found in Ba 3 ThSe 3 (Se 2 ) 2 [2.374(1) and 2.377(1) Å], KU 2 SbSe 8 [2.356(5) to 2.375(4) Å], USe 3 (2.361 Å), KAuSe 5 [2.362(1) to 2.343(1) Å], Cs 4 Ge 2 Se 8 (2.350 Å), CsAuSe 3 (2.384 Å), and RbPdCu(Se 2 )(Se 3 ) [2.338(2) Å] . In addition to these normal single bonds, this structure also show short Se ··· Se ··· Se interactions with alternating distances of 2.595(1) and 2.610(1) Å that are longer than a normal single bond and are shorter than the van der Waals interactions (ca.…”

Synthesis and Characterization of Ba2Ag2Se2(Se2)

“…The Se1 and Se4 atoms of the superstructure form Se1–Se4 dimers, i.e., Se 2 2– units. The Se1–Se4 distance of 2.378(2) Å is in good agreement with the single Se–Se bond distances found in orthorhombic CuSe [2.341(1) Å], KAuSe 5 [2.362(1)–2.343(1) Å], Cs 4 Ge 2 Se 8 [2.350(1) Å], CsAuSe 3 [2.384(1) Å], Ba 8 PdU 2 Se 12 (Se 2 ) 2 [2.392(1) and 2.407(1) Å], Cs 2 U 2 P 2 Se 9 (Se 2 ) 2 [2.403(1) and 2.409(1) Å], and Ba 3 ThSe 3 (Se 2 ) 2 [2.374(1) and 2.377(1) Å] …”

“…The band gap of Ba 2 Ag 2 Se 2 (Se 2 ) was investigated using the following equation: Here α, h , ν, A , and E g are respectively the absorption coefficient, Planck constant, frequency of light, proportionality constant, and band gap. When n = 1 / 2 , the band gap is indirect; when n = 2, the band gap is direct. , …”

K(Th0.75Sr0.25)2Se6: Structural Change Resulting from the Disorder of Differently Charged Cations

“…One site contains 3/1 Th 4+ /Sr 2+ . The incorporation of the divalent element breaks the infinite Se–Se–Se chains to yield classical Se–Se pairs, as observed in the structures of ZrSe 3 and Ba 3 ThSe 3 (Se 2 ) 2 …”