Dramatically improved optical anisotropy by realizing stereochemically active lone pairs in a sulfate system, K2SO4·HIO3†
Abstract
Obtaining sulfate-based materials with large birefringence is of great challenge due to the weak polarizability anisotropy of the constituting spherical SO42− tetrahedron. Here, we have implemented a polyhedron of stereoactive lone pair cations, IO3− to the system to tackle the issue. Centimetre-sized single crystals of an alkali metal sulfate iodate, K2SO4·HIO3, have been readily grown by an accessible solution–evaporation method. Optical measurements on K2SO4·HIO3 single crystals reveal that the reported material exhibits a 70-fold increase in birefringence (ca. 0.14 at 589.3 nm) compared to that of the singular sulfate, K2SO4. In addition, K2SO4·HIO3 exhibits a blue-shifted UV cutoff edge of 275 nm, 25 nm shorter than that of α-HIO3, highlighting the key role of the SO42− tetrahedron in broadening the transmittance window.
- This article is part of the themed collection: 2023 Inorganic Chemistry Frontiers HOT articles