Syntheses, structures, and optical properties of Ba₄Ga₄SnSe₁₂and Ba₆Ga₂SnSe₁₁

Abstract

Two new quaternary selenides, namely Ba4Ga4SnSe12 and Ba6Ga2SnSe11, have been synthesized for the first time, representing the first two members in the A/M/Sn/Q (A = alkaline-earth metal; M = Al, Ga, In; Q = S, Se, Te) system. Ba4Ga4SnSe12 crystallizes in the non-centrosymmetric space group P4[combining macron]21/c of the tetragonal system and has a three-dimensional structure. Its three-dimensional framework is built up from corner-sharing GaSe4 and SnSe4 tetrahedra with eight-coordinated Ba(2+) cations residing in the cavities. Ba6Ga2SnSe11 crystallizes in a new structure type in the monoclinic centrosymmetric space group P21/c. The structure of Ba6Ga2SnSe11 features a zero-dimensional structure containing totally isolated distorted SnSe4 tetrahedra and a discrete Ga2Se7 unit with Ba(2+) cations located between them. On the basis of the diffuse-reflectance spectra, the band gaps are 2.16 (2) eV and 1.99 (2) eV for Ba4Ga4SnSe12 and Ba6Ga2SnSe11 respectively. In addition, the electronic structure calculation of Ba4Ga4SnSe12 indicates that it is a direct-gap semiconductor with the band gap mainly determined by the [Ga4SnSe12](8-) anionic framework.

Exploring the electronic structure and optical properties of the quaternary selenide compound, Ba4Ga4SnSe12: For photovoltaic applications

“…From our calculations, we estimated the value of the band gap to Eg= 2.14 eV. This is very close to the experimental measurement (2.16 eV) and shows that the full potential calculations describe correctly the present selenide compared to the pseudo-potential method (which led to a band gap value of 1.42 eV) [15]). Principally, the energy structure of the materials depends on the interactions between orbital in the lattice.…”

“…In the present study, we thought it would be worthwhile to perform calculations by considering a full potential approach and we used all electrons full potential linear augmented plane wave method. Our calculation has led to band gap very close to the experimental value [15]. Hence, we completed our investigation by bonding characterization and optical properties to explore its potential application as material for photovoltaic devices.…”

“…114) (see Fig.1). Lattice constants and atomic coordinates were obtained from the experimental measurements [15]. The structure of Ba 4 Ga 4 SnSe 12 was fully relaxed before proceeding with further calculations.…”

“…Yin et al [15] in early studies developed the quaternary A/M/M′/Q (A = alkaline-earth metal; M = Al, Ga, In; M′ = Si, Ge; Q = S, Se, Te) system and originate four iso-structural compounds, BaGa 2 MQ 6 (M = Si, Ge; Q = S, Se), which were described to be a new-fangled series of IR nonlinear optical materials showing promise for practical applications. Recently, Yin et al [15] have presented the synthesis, structural characterizations, and band gap measurements of an interesting quaternary selenide, Ba 4 Ga 4 SnSe 12 . They also reported its electronic band structure calculated using the plane-wave pseudo-potential method.…”

“…Rare-earth chalcogenides have exhibited not only rich structures resulting from the diverse geometry of the Ln centered coordination polyhedra and the flexible connectivity among them, but also attractive magnetic, transport, and optical properties related to the 4f electrons [14]. Yin et al [15] in early studies developed the quaternary A/M/M′/Q (A = alkaline-earth metal; M = Al, Ga, In; M′ = Si, Ge; Q = S, Se, Te) system and originate four iso-structural compounds, BaGa 2 MQ 6 (M = Si, Ge; Q = S, Se), which were described to be a new-fangled series of IR nonlinear optical materials showing promise for practical applications. Recently, Yin et al [15] have presented the synthesis, structural characterizations, and band gap measurements of an interesting quaternary selenide, Ba 4 Ga 4 SnSe 12 .…”