The quaternary chalcogenide halides Ba₃GaSe₄Br and Ba₃InSe₄Br were prepared from reactions of binary selenides and bromides at 1073 K. Single-crystal X-ray diffraction analysis revealed that Ba₃GaSe₄Br adopts the Ba₃GaS₄Cl-type structure (orthorhombic, space group Pnma, Z = 4, a = 12.8248(6) Å, b = 9.9608(5) Å, c = 8.7690(4) Å) and Ba₃InSe₄Br adopts the K₃SO₄F-type structure (tetragonal, space group I4/mcm, Z = 4, a = 8.6888(16) Å, c = 14.950(3) Å). Both structures contain isolated [MSe₄]^5– tetrahedral units separated by Ba²⁺ and Br^– ions. A structure map based on radius ratios is able to demarcate the three structure types encountered for various members of the series of chalcogenide halides Ba₃MCh₄X (M = Al, Ga, In; Ch = S, Se; X = Cl, Br, I). Large band gaps in Ba₃GaSe₄Br and Ba₃InSe₄Br originate from the separation of Ga–Se or In–Se bonding and antibonding levels, as revealed by electronic structure calculations. The measured optical band gaps are 1.7 eV for Ba₃GaSe₄Br and 1.6 eV for Ba₃InSe₄Br.

由二元硒化物和溴化物在1073 K下反应制得季铵化卤化物Ba ₃ GaSe ₄ Br和Ba ₃ InSe ₄ Br。单晶X射线衍射分析表明Ba ₃ GaSe ₄ Br采用Ba ₃ GaS ₄ Cl型结构（斜方晶，空间群Pnma，Z  = 4，a  = 12.8248（6）Å，b  = 9.9608（5）Å，c  = 8.7690（4）Å），Ba ₃ InSe ₄ Br采用K ₃ SO ₄ F型结构（四边形，空间群我4 / MCM，Ž  = 4，一个 = 8.6888（16）埃，c ^  = 14.950（3））。两种结构都包含孤立[中号硒₄ ] ^5-四面体单元分离由Ba ²⁺和Br ^-离子。基于半径比的结构图能够划分出硫族元素卤化物Ba ₃ MCh ₄ X系列中各个成员遇到的三种结构类型（M  = Al，Ga，In；Ch  = S，Se；X  = Cl，Br ， 一世）。Ba ₃ GaSe ₄ Br和Ba _3中的带隙较大InSe ₄ Br源自Ga-Se或In-Se键和反键能级的分离，这是通过电子结构计算得出的。对于Ba ₃ GaSe ₄ Br，所测量的光学带隙为1.7 eV，对于Ba ₃ InSe ₄ Br，其光学带隙为1.6 eV 。