Hg2P2S6: A layered mercury hexathiodiphosphate (IV) with large birefringence.

Birefringent materials are very important in the laser industry. By combining the hexathiodiphosphate(IV) [P 2 S 6 ]4- unit and the highly polarizable Hg2+, a mercury hexathiodiphosphate(IV) Hg 2 P 2 S 6 was designed and synthesized by using solid-state synthesis. Hg 2 P 2 S 6 crystallizes in P 1 ¯ space group. It has a layered structure as in many hexathiodiphosphates(IV) such as ZnPS 3 , CdPS 3. Its crystal structure, electronic structure and optical properties are investigated by experimental methods and first-principle calculations. Hg 2 P 2 S 6 has a very large birefringence of 0.50 ​at 1064 ​nm and 0.48 ​at 2050 ​nm. Theoretical studies show the large birefringence comes from the synergistic effect of [P 2 S 6 ]4- and [HgS 4 ]6- groups with strong polarizability anisotropy. By combining the hexathiodiphosphate (IV) [P 2 S 6 ]4- unit and the highly polarizable Hg2+, a mercury hexathiodiphosphate (IV), namely, Hg 2 P 2 S 6 with large birefringence was designed and synthesized. It's found that the synergistic effect of the favourably arranged [P 2 S 6 ]4- and [HgS 4 ]6- groups with high polarizability anisotropy leads to its large birefringence. [Display omitted] • The properties of a mercury hexathiodiphosphate (IV), Hg 2 P 2 S 6 has been studied by experimental and theoretical methods. • Hg 2 P 2 S 6 has a very large birefringence compared with most of its counterparts. • The synergistic effect of the favourably arranged [P 2 S 6 ]4- and [HgS 4 ]6- groups leads to its large birefringence. [ABSTRACT FROM AUTHOR]