MB 3 P 2 S 10 (M = Rb, Cs): two new alkali metal thioboratephosphates with [B 6 P 4 S 20 ] T3-supertetrahedra.

Two new alkaline metal thioboratephosphates, RbB 3 P 2 S 10 and CsB 3 P 2 S 10 , have been designed and fabricated by the flux method. The two compounds are composed of alkali metal polyhedral and [B 6 P 4 S 20 ] T3-supertetrahedral units, and crystallize in I 4 1 / a and R 3̄ c space groups, respectively. The results enrich the chemical diversity of chalcogenides, and give insights for the exploration of new functional materials in thioboratephosphates.