The system vanadium-selenium near the composition VSe

Abstract

Compositions VSex (x = 0·90–1·13) were prepared directly by heating the elements. Three series with different temperature treatments were examined. Samples quenched from 1000°C all appeared to have only one phase with a NiAs-type structure. The series, cooled very slowly, had two one-phase-regions with NiAs-type structure, namely “VSe” between VSe0·98 and VSe1·02 with a = 3·697 Å and C = 5·990 Å and “V29Se32” between VSe1·10 and VSe1·11 with a = 3·606 Å and C = 6·001 Å. The latter phase exhibited a superstructure with a′ = 2a of the NiAs-cell and c′ = 4c of the NiAs-cell (a′ = 7·211 Å and c′ = 24·002 Å.