Six isostructural antiperovskite-derived chalcohalides, Ba₂MQ₃X (M = As, Sb; Q = S, Se; X = Cl, Br, I), crystallizing in the space group Pnma, have been synthesized by solid-state reactions. The crystal structure features a 3D framework with the [XBa₅]⁹⁺ disordered square pyramids as building blocks and [MQ₃]^3– units filling the interspace. [XBa₅]⁹⁺ disordered square pyramids are edge-sharing along [010], derived from the fusing of the two pyramids in octahedral [XBa₆]¹¹⁺. Surprisingly, Ba₂AsS₃X (X = Cl, Br, I) show almost the same optical band gap of 2.80 eV, and Ba₂AsSe₃X (X = Br, I) also have a similar band gap of 2.28 eV. The optical band gap of Ba₂SbS₃I is 2.64 eV. First-principles calculations reveal that the optical absorption is attributed to the transitions between Q np at the valence band maximum (VBM) and M np–Q np at the conduction band minimum (CBM). These compounds also possess interesting photoluminescence properties with splitting emission peaks on excitation at 200 nm.

中文翻译：

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抗钙钛矿衍生的Ba ₂ MQ ₃ X（M = As，Sb; Q = S，Se; X = Cl，Br，I）的合成，结构和光学性质

通过固相反应合成了六种等结构的抗钙钛矿衍生的黄铜卤化物，Ba ₂ MQ ₃ X（M = As，Sb; Q = S，Se; X = Cl，Br，I），它们在空间群Pnma中结晶。晶体结构具有3D框架，其中[XBa ₅ ] ⁹⁺无序方形金字塔作为构建基块，[MQ ₃ ] ^3–单元填充了间隙。[XBa ₅ ] ⁹⁺无序方形金字塔沿[010]沿边共享，其源自八面体[XBa ₆ ] ^11+中两个金字塔的融合。令人惊讶的是，Ba ₂ AsS ₃X（X = Cl，Br，I）显示几乎相同的2.80 eV光学带隙，Ba ₂ AsSe ₃ X（X = Br，I）也具有相似的2.28 eV的带隙。Ba ₂ SbS ₃ I的光学带隙为2.64eV 。第一原理计算显示，光吸收归因于Q之间的过渡Ñ在价带最大值（VBM）和量m P Ñ P-Q Ñ p在导带最小值（CBM）。这些化合物还具有令人感兴趣的光致发光特性，在200 nm激发时会分裂出发射峰。