BaPb2(CO3)2F2: Enhancing Birefringence by a Multiunit Synergy Effect

作者：Yuan Lin, Rongfang Zhang, Yucheng Hao, Ming-Yang Cao, Xuanlin Pan, Jiang‐Gao Mao · 发表于：Inorganic Chemistry · 年份：2024 · DOI：10.1021/acs.inorgchem.4c04004 · 被引用次数：8 · 研究领域：Crystal Structures and Properties、Inorganic Fluorides and Related Compounds、Luminescence Properties of Advanced Materials

Carbonates are ideal birefringent materials because their π-conjugated [CO 3 ] groups are beneficial for large anisotropy. How to maximize the birefringence and maintain a wide transmittance simultaneously in carbonates is a great challenge. Adopting a multiple-functional group synergy strategy by combining alkaline-earth metal Ba 2+ with large ion radius, PbO 6 F distorted hexagonal pyramid, and paralleled π-conjugated CO 3 triangles together, we synthesized a new metal carbonate crystal, BaPb 2 (CO 3 ) 2 F 2 . BaPb 2 (CO 3 ) 2 F 2 features a typical two-dimensional layered structure, which consists of a PbCO 3 F monolayer parallel to the ab plane and Ba 2+ cations filled between the monolayers. BaPb 2 (CO 3 ) 2 F 2 exhibits a large experimental birefringence of approximately 0.245@546 nm and a short ultraviolet absorption edge down to 264 nm (Eg = 4.70 eV), indicating that it is a promising ultraviolet birefringent material. The reported highest experimental birefringence index among carbonate crystals is surpassed by BaPb 2 (CO 3 ) 2 F 2 . The theoretical calculation shows that the contribution percentages for total birefringence are 57 and 43% for the CO 3 group and PbO 3 F group, respectively. Our work offers a new route for designing new birefringent materials with excellent comprehensive performance.