ABSTRACT Optical crystals with wide bandgap for deep ultraviolet (DUV) range are pivotal for the modern laser technologies, particularly in the field of solid‐state lasers. In this work, a DUV transparent magnesium‐ammonium sulfate (NH 4 ) 2 Mg(SO 4 ) 2 ·6H 2 O is successfully obtained through an aqueous solution evaporation method. It crystallizes in P 2 1 / c space group with cell parameters of a = 6.1940(11) Å, b = 12.582(2) Å, c = 9.3105(16) Å, and β = 107.095(5) °. Based on centimeter‐scale crystals, transmission spectra reveals that the crystal exhibits high transmittance in the range of 300–3000 nm with a DUV cutoff edge at 190 nm. This excellent DUV transparency is attributed to the rigid SO 4 tetrahedra, a structural unit well‐established for its favorable contribution to a large bandgap. Meanwhile, the birefringence measurement indicates that the maximum refractive index difference of this compound is 0.03@589.3 nm. This study introduces a promising optical crystal with a short cut‐off edge and enriches the functional properties research of the sulfate family.
Chen et al. (Wed,) studied this question.