[en] Three new diamond-like compounds with the formula of I₂−II−IV−VI₄ (I=Cu; II=Mg; IV=Si, Ge; VI=S, Se) have been synthesized via traditional high-temperature solid-state reactions and structurally characterized by single crystal X-ray diffraction analysis. All the three compounds crystallize in the space group Pmn2₁ in the wurtzite-type superstructure with a=7.563(4), b=6.448(3), c=6.179(3) Å, Z=2 for Cu₂MgSiS₄ (1); a=7.953(5), b=6.797(4), c=6.507(4) Å, Z=2 for Cu₂MgGeS₄ (2); a=7.638(4), b=6.515(4), c=6.225(3) Å, Z=2 for Cu₂MgSiSe₄ (3). All atoms in these compounds are tetrahedrally coordinated. Optical diffuse reflectance UV/Vis/NIR spectra indicate that compounds 1 and 2 have the band gaps of 3.20 and 2.36 eV, respectively. Electronic structure calculations using the CASTEP code indicate that they are all direct band gap compounds. - Graphical abstract: Three new diamond-like compounds, Cu₂MgSiS₄, Cu₂MgGeS₄, and Cu₂MgSiSe₄, have been synthesized. All the three compounds crystallize in the space group Pmn2₁ and all atoms are tetrahedrally coordinated. Highlights: • Three new diamond-like compounds Cu₂MgSiS₄, Cu₂MgGeS₄ and Cu₂MgSiSe₄ have been synthesized. • All ions are tetrahedrally coordinated. • Electronic structure calculations indicate that they are all direct band gap compounds

[en] Graphical abstract: - Highlights: • A new compound NaIn_3S_5 has been obtained in the CaS–In_2S_3/NaBr system. • NaIn_3S_5 crystallizes in a new structure type. • The experimental band gap is 2.18 eV for NaIn_3S_5. • The electronic structure of NaIn_3S_5 has been calculated. - Abstract: A new compound NaIn_3S_5 has been obtained in the CaS–In_2S_3/NaBr system via a reactive flux method. NaIn_3S_5 crystallizes in the orthorhombic space group Pbam (No. 55) with a = 12.4963(8) Å, b = 16.0811(10) Å, c = 3.8041(2) Å, and Z = 4. The NaIn_3S_5 structure is characterized by a three dimensional framework consisting of interconnected tripartite-octahedral "1_∞[In_3S_8] infinite chains, with Na"+ cations residing in the one-dimensional channels along the c direction defined by S(1), S(2), S(3) and S(4) atoms. The optical reflectance measurement shows a band gap of 2.18 eV for NaIn_3S_5. Electronic structure calculation by the CASTEP code not only indicates that NaIn_3S_5 is an indirect band gap semiconductor, but also explains why its experimental band gap is close to that of β-In_2S_3

[en] A large nonlinear optical (NLO) coefficient and a wide band gap are two crucial but contradictory parameters that are difficult to achieve simultaneously in a single infrared (IR) NLO compound. A salt-inclusion chalcogenide (SIC), Li[LiCs${}_2$Cl][Ga${}_3$S${}_6$] (1), was prepared that presents a nanosized tunnel framework constructed from monotype chalcogenide tetrahedra. Highly oriented covalent GaS${}_4$ tetrahedra in the host lead to a moderate second harmonic generation response (0.7 AgGaS${}_2$), and ionic guests effectively broaden the band gap to the widest value (4.18 eV) among all IR NLO chalcogenides, thereby achieving a remarkable balance between NLO efficiency and band gap. (© 2019 Wiley‐VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] The first indiumsilicate oxysulfide Ba_2In_2Si_3O_1_0S (1) was obtained by an alkali polychalcogenide flux method through a high-temperature solid-state reaction. It crystallizes in the non-centrosymmetric space group Pca2_1 (No. 29), with a = 23.060(6), b = 5.2954(6), c = 8.779(2) Aa, and Z = 4. Its three-dimensional (3D) framework is constructed from one-dimensional (1D) infinite _∞"1[In_2O_7S_2_/_2] double octahedral chains bridged by corner-sharing Si tetrahedral trimers [Si_3O_1_0]"8"-, yielding a 3D framework with the channels filled with Ba"2"+ cations along the b direction. It is unprecedented in that the two distorted indium octahedra in 1 face-share to form a [In_2O_7S_2] dimer in indium oxides and oxide chalcogenides. (Copyright copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)