Ba<sub>3</sub>HgGa<sub>2</sub>S<sub>7</sub>: A Zero-Dimensional Quaternary Sulfide Featuring a Unique [Hg<sub>2</sub>Ga<sub>4</sub>S<sub>14</sub>]<sup>12–</sup> String and Exhibiting a High Photocurrent Response
Xiao Huang, Sihan Yang, Wenlong Liu, Sheng‐Ping Guo
Abstract
The discovery of new types of metal sulfides is attractive because of their rich structures and diverse physical properties. Here, a novel quaternary sulfide, Ba3HgGa2S7 (BHGS), is obtained by a solid-state reaction at 1123 K. It crystallizes in the monoclinic space group P21/c, and its zero-dimensional structure features two seesaw-like HgS2 units and four GaS4 tetrahedra, constructing a unique [Hg2Ga4S14]12– string. BHGS has a wide band gap of 3.64 eV and a large birefringence of 0.09 at 2100 nm. Specifically, BHGS exhibits a remarkable photocurrent response. This work may be extended to a new family of AE3MIIMIII2Q7 (AE = Mg, Ca, Sr, Ba; MII = Zn, Cd, Hg; MIII = Al, Ga, In; Q = S, Se) chalcogenides.