Synthesis, structure, and optical properties of the quaternary diamond-like compounds I2–II–IV–VI4 (I=Cu; II=Mg; IV=Si, Ge; VI=S, Se)

<i>Ab Initio</i> Study of the Relative Stability and Opto-Electronics Properties of the Cu2MgSiS4 Compound

“…The calculated values of the atomic coordinates, lattice constants, equilibrium volume, bulk modulus and its pressure derivative are summarized in Table I with other available results. For the WS structure, the structural parameters are in good agreement with the experimental and theoretical data [26,28]. For the other structures, to the best of our knowledge, no experimental or theoretical data are available for comparison.…”

“…Recently, Cu 2 MgSiS 4 compound has been synthesized via high-temperature solid-state reactions and structurally characterized by single crystal X-ray diffraction analysis which reveal that this compound crystallizes in orthorhombic structure space group P mn 21 [26]. The optical absorption spectra, obtained from the optical diffuse reflectance spectra of a powder sample of this compound measured at room temperature, gives an optical band gap value of 3.20 eV.…”

Syntheses and crystal structures of the quaternary thiogermanates Cu4FeGe2S7and Cu4CoGe2S7

“…(Brunetta et al, 2013). The monovalent ions incorporated in these materials include Li (Wu, Zhang, et al, 2017;, Cu (Parthé et al, 1969) or Ag (Brunetta et al, 2013) and the divalent ions include a number of metals, such as Mg (Liu et al, 2013), Mn (Bernert & Pfitzner, 2005), Fe (Wintenberger, 1979), Co (Bernert and Pfitzner 2006), Zn (Parasyuk et al, 2001), Cd (Rosmus et al, 2014) and Hg (Olekseyuk et al, 2005). The tetravalent ions found in these compounds are usually Si, Ge, or Sn, while the hexavalent atoms (i.e., the divalent anions) can be S (Lekse et al, 2009), Se (Gulay, Romanyuk & Parasyuk, 2002), or Te (Parasyuk et al, 2005).…”

“…The tetravalent ions found in these compounds are usually Si, Ge, or Sn, while the hexavalent atoms (i.e., the divalent anions) can be S (Lekse et al, 2009), Se (Gulay, Romanyuk & Parasyuk, 2002), or Te (Parasyuk et al, 2005). Some specific examples include Cu 2 MgGeS 4 (Liu et al, 2013) and Ag 2 MnSnS 4 (Friedrich et al, 2018). In contrast, considerably fewer compounds of the general formula I 4 -II-IV 2 -VI 7 have been discovered: only seven of these, which crystallize in either space group C2 or Cc with structures derived from cubic or hexagonal diamond, respectively, have been published to date: Li 4 MnGe 2 S 7 (Cc) (Kaib et al, 2013), Li 4 MnSn 2 Se 7 (Cc) (Kaib et al, 2013), Li 4 HgGe 2 S 7 (Cc) (Wu, Yang, Pan 2017), Ag 4 HgGe 2 S 7 (Cc) (Gulay, Olekseyuk & Parasyuk 2002), Ag 4 CdGe 2 S 7 (Cc) (Gulay, Olekseyuk & Parasyuk 2002), Cu 4 NiSi 2 S 7 (C2) (Schä fer et al, 1980), and Cu 4 NiGe 2 S 7 (C2) (Schä fer et al, 1980).…”

Cu2ZnSnS4, Cu2ZnSnSe4, and Related Materials

“…The band structure of Cu 2 ZnSnSe 4 is similar to that of Cu 2 ZnSnS 4 , but the band gap size is smaller, at 1.0 eV [60]. In early literature, the band gap of Cu 2 ZnSnSe 4 had been reported to be around 1.5 eV, close to that of Cu 2 ZnSnS 4 [71][72][73]. Our DFT calculations at the level of the local density approximation (LDA) or generalized gradient approximation (GGA) clearly showed that the gap of the selenide should be about 0.5 eV smaller than that of the sulfide.…”