Highly Birefringent d0 Transition Metal Fluoroantimonite in the Mid Infrared Band: Order-Disorder Regulation by Cationic Size.

An unusual O/F ordered d0 transition metal fluoroantimonite, namely, K2SbMoO2F7, has been created by the cationic size effect of alkali metals. It features the largest birefringence of 0.220@550 nm among inorganic antimonites with a halogen element, which is an order of magnitude larger than the disordered A2SbMoO2F7 (A = Rb, Cs). These three new compounds exhibit two different structures, although all of the structures were made of [SbMoO2F7]2- chains formed by SbF5 square pyramids and MoO2F4 octahedrons. A transparent single crystal of K2SbMoO2F7 with dimensions of 7.0 × 5.0 × 1.0 mm3 has been successfully grown by the aqueous solution volatilization method. The UV-vis-MIR transmission spectrum showed that K2SbMoO2F7 can display excellent transmittance in the range of 0.5-5.0 µm and 6.0-9.8 µm, indicating its application potential as a birefringent material in the mid infrared band. This work offers a fresh approach to the design and synthesis of mid infrared birefringent materials.

A three-dimensional cuprous lead bromide framework with highly efficient and stable thermochromic luminescence properties.

Herein, by using a structural design strategy of incorporating hetrometallic halide blocks, we prepared the first 3D bimetallic halide of [H2DABCO]2Cu6PbBr12 with new topological network based on two types of 6-connected nodes. Remarkably, this 3D framework displays highly efficient thermochromic luminescence from broadband yellow to green light emissions with remarkable stability.