3Pb8O7I2·2CsI: Salt-inclusion strategy enriches the structural chemistry in lead oxyhalides

Abstract

The design and synthesis of new mid-infrared functional crystals with novel structures and excellent properties is a hot topic in the material scientific research field. Different from the traditional mid-far infrared crystals system, such as chalcogenides and phosphides, a recently developed heavy metal oxyhalide system, with a wide bandgap and transmittance range, is a very promising mid-infrared crystal material research system. Herein, the first case of the salt-inclusion compound in lead oxyhalide, Cs2Pb24O21I8 (3Pb8O7I2·2CsI), has been synthesized by a high-temperature solution method. Cs2Pb24O21I8 features a “chain” like structure constructed by 1∞[O21Pb30] chain composed of [OPb4] tetrahedra and [OPb3] pyramid, then 1∞[CsI4] chain inserted in the tunnel. The results show that the salt-inclusion strategy significantly enriches the structure diversity of lead oxyhalides and provides a new research idea for exploring new infrared functional materials.