Notizen: DerPolymerisationsgrad des Metavanadations (VO₃)_n ^n⊖ nach Untersuchungen des Sedimentations-Gleichgewichtes mit der Ultrazentrifuge

Abstract

Single-phase Pr 2 CBr was prepared by heating a mixture of PrBr 3 , Pr and C (1 : 5:3) to 1140 • C for 18 d. The crystal structure was investigated by X-ray single crystal diffraction (space group P6 3 /mmc, a = 3.8071 (3), c = 14.7787(12)Å). In the structure the Pr atoms form C-centered octahedra condensed into Pr 2 C sheets via common edges; these sheets are separated by the Br atoms which are in a trigonal prismatic environment of Pr atoms. Pr 2 CBr is a black shiny compound with metallic conductivity. It is a ferromagnet with T c = 13.8(5) K.