Layered Ordered Multianion Semiconductor Bi 18 O 21.6 Se 1.8 Cl 7.2 with Low c -Axial Thermal Conductivity

作者：Zhijun Tu, Wenju Zhou, Zhenghui Fang, Yizhe Liu, Yuting Yang, Shangjie Tian, Shouguo Wang, Xiaofeng Liu, Peiyang Mu, Tianqi Gao, Bo Sun, Huiyang Gou, Xiao Zhang, Hechang Lei · 发表于：Inorganic Chemistry · 年份：2025 · DOI：10.1021/acs.inorgchem.5c00539 · 研究领域：Advanced Condensed Matter Physics、Crystal Structures and Properties、Advanced Thermoelectric Materials and Devices

Layered ordered multianion materials exhibit remarkable structural flexibility and unique chemical and physical properties, which arise from the interplay of intralayer and interlayer interactions, as well as distinct local chemical environments originating from different anionic sublattices. Here, we report a novel layered quaternary compound, Bi 18 O 21.6 Se 1.8 Cl 7.2, which features three different anionic sublattices. Bi 18 O 21.6 Se 1.8 Cl 7.2 consists of [Bi 6 O 9.6 Cl 6 ] and [Bi 12 O 12 Se 1.8 Cl 1.2 ] slabs that stack along the c axis alternatively. Comprehensive physical properties and electronic properties of Bi 18 O 21.6 Se 1.8 Cl 7.2 single crystals reveal semiconducting behavior with an indirect band gap of ∼1.51 eV and the dominant electron-type carriers. Notably, Bi 18 O 21.6 Se 1.8 Cl 7.2 exhibits exceptionally low c -axial thermal conductivity κ c (∼0.261–0.307 W m –1 K –1 ) at room temperature, significantly expanding the phase space of the ultralow-thermal-conductivity Bi–O–Se–Cl system. Our findings highlight that the strategic combination of distinct two-dimensional building blocks with varied structural and anionic coordination environments offers an effective approach for designing new layered materials with tunable physical properties.