Hg 3 Se(SeO 3 )(SO 4 ): A Mixed-Valent Selenium Compound with Mid-Infrared Transmittance Obtained by In Situ Reaction.

Exploring new material systems is a highly significant task in the field of inorganic chemistry. A new mixed-valent selenium compound, Hg 3 Se(SeO 3 )(SO 4 ), was successfully synthesized through in situ reactions. This compound exhibits a novel three-dimensional structure composed of Hg 3 Se(SO 4 ) layers bridged by SeO 3 trigonal pyramids. It is the first structure containing (SeO 3 ) 2- , (SO 4 ) 2- , and Se 2- simultaneously. In addition, Hg 3 Se(SeO 3 )(SO 4 ) possesses a wide bandgap (3.5 eV), moderate birefringence (Cal:0.064@546 nm, Exp:0.069@546 nm), a high laser-induced damage threshold (23.35 MW cm -2 ), and a wide transmittance window (0.28-6.6 μm). Our work demonstrates that mixed-valent (+4, -2) selenite selenide can be potential optical materials for the mid-infrared region.