HgB2S4: A d 10 Metal Thioborate with Giant Birefringence and Wide Band Gap

Birefringent crystals are importantoptical devices invariousadvanced optical systems because they can create and control polarizedlight. In this work, the capability of planar [B3S6] to produce large birefringence was theoretically studiedfor the first time. Moreover, the first d (10) metal thioborate HgB2S4 (HBS) has been synthesizedsuccessfully, which was constructed by the pi-conjugated [B3S6] and [HgS2] units. Notably, HBS showsgreat potential to be an infrared birefringent material due to itslarge birefringence, Delta n = 0.52 @ 1064 nm (similar to 4.3x alpha-BaB2O4 and similar to 10.4 xAgGaS(2) @ 1064 nm), wide band gap of 3.36 eV, and wide transparentwindow (similar to 0.37-25 mu m). To the best of our knowledge,both the birefringence and the band gap of HBS are the largest amongmercury sulfides. Structure-performance analyses reveal that the pi-conjugated[B3S6] units are the main birefringence contributorand could be regarded as a good unit for designing IR birefringentmaterials. This work will provide direct guidance to design high performancebirefringent crystals in the future.

Automated summary

In this work, the capability of planar [B3S6] to generate large birefringence was theoretically studied for the first time. The first d (10) metal thioborate HgB2S4 (HBS) was successfully synthesized, which was composed of the pi-conjugated [B3S6] and [HgS2] units. HBS showed great potential as an infrared birefringent material due to its large birefringence, wide band gap, and wide transparent window. The structure-performance analysis revealed that the pi-conjugated [B3S6] units were the main contributor to birefringence and could be used for designing IR birefringent materials. This research will have a direct impact on the design of high-performance birefringent crystals in the future.