Bi metal dissolves in excess molten phosphorus selenide at 500 °C to yield black, rodlike, air- and water-stable β-Bi4(P2Se6)3 crystals. The phase crystallizes in the triclinic space group P1̄ (No. 2) with the room-temperature cell parameters a = 12.2303(8) Å, b = 6.7640(4) Å, c = 17.866 Å, α = 90.493(6)°, β = 94.133(6)°, and γ = 91.163(6)°. The new structure is a complicated, three-dimensional framework built from [Bi4Se22] ribbons connected to each other by sharing selenium atoms. The [P2Se6]4- ethane-like units are found inside and between the [Bi4Se22] ribbons. The compound is a semiconductor with a band gap of 1.32 eV. It melts with decomposition at 512 °C, converting partially to Bi2Se3 and a PxSey glassy material. Far-IR and Raman spectra show characteristic stretches for the [P2Se6]4- ligand and Bi-Se vibrations. The structural and chemical relationships of this compound with the α-form are discussed.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry