beta-Bi(4)(P(2)Se(6))(3): A New Ternary Selenophosphate Obtained in a P(2)Se(5) Flux.
Bi metal dissolves in excess molten phosphorus selenide at 500 degrees C to yield black, rodlike, air- and water-stable beta-Bi(4)(P(2)Se(6))(3) crystals. The phase crystallizes in the triclinic space group P&onemacr; (No. 2) with the room-temperature cell parameters a = 12.2303(8) Å, b = 6.7640(4) Å, c = 17.866 Å, alpha = 90.493(6) degrees, beta = 94.133(6) degrees, and gamma = 91.163(6) degrees. The new structure is a complicated, three-dimensional framework built from [Bi(4)Se(22)] ribbons connected to each other by sharing selenium atoms. The [P(2)Se(6)](4)(-) ethane-like units are found inside and between the [Bi(4)Se(22)] ribbons. The compound is a semiconductor with a band gap of 1.32 eV. It melts with decomposition at 512 degrees C, converting partially to Bi(2)Se(3) and a P(x)()Se(y)() glassy material. Far-IR and Raman spectra show characteristic stretches for the [P(2)Se(6)](4)(-) ligand and Bi-Se vibrations. The structural and chemical relationships of this compound with the alpha-form are discussed.
Aitken
Jennifer A.
JA
Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, and Institut des Matériaux de Nantes, B.P. 32229, 44322 Nantes Cedex 03, France.
Brown
Shannon
S
Chondroudis
Konstantinos
K
Jobic
Stéphane
S
Brec
Raymond
R
Kanatzidis
Mercouri G.
MG