The diversity of halide materials related to important solar energy systems such as CsPbX₃ (X = Cl, Br, I) is explored by introducing the transition metal element Fe. In particular a new compound, Cs₃Fe₂Br₉ (space group P6₃/mmc with a = 7.5427(8) and c = 18.5849(13) Å), has been synthesized and found to contain 0D face-sharing Fe₂Br₉ octahedral dimers. Unlike its isomorph, Cs₃Bi₂I₉, it is black in color, has a low optical bandgap of 1.65 eV and exhibits antiferromagnetic behavior below T_N = 13 K. Density functional theory calculations shed further light on these properties and also predict that the material should have anisotropic transport characteristics.

中文翻译：

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铯基过渡金属卤化物Cs ₃ Fe ₂ Br _9的合成，晶体结构，磁性和电子性质

通过引入过渡金属元素Fe，探索了与重要太阳能系统有关的卤化物材料的多样性，例如CsPbX ₃（X = Cl，Br，I）。特别是合成了一种新的化合物Cs ₃ Fe ₂ Br ₉（空间群P 6 ₃ / mmc，a = 7.5427（8）和c = 18.5849（13）Å），发现该化合物包含0D面共享Fe ₂ Br ₉八面体二聚体。与同构不同，Cs ₃ Bi ₂ I ₉，它是黑色的，具有1.65 eV的低光学带隙，并且在T _N = 13 K以下具有反铁磁行为。密度泛函理论计算进一步揭示了这些性质，并预测该材料应具有各向异性的传输特性。