On the Structural Properties of the Ta(1+x)Se2 Phase.

Abstract

The Nb(1+x)Se2 phase has a homogeneity range within the limits 60.8 (61.5 for samples quenched from 1000 C) and 66.67 atomic % Se. The structure is hexagonal and the lattice constants vary between the limits Nb1.29Se2: a=3.450 A, c=13.02 A, c/a=3.774 (Nb1.25Se2: a=3.425 A, c=12.92 A, c/a=3.743 for samples quenched from 1000 C) Nb1.00Se2: Nb1.29Se2: a=3.446 A, c=12.55 A, c/a=3.643 Between ~63 and ~65.5% at the existence of superstructure has been observed. As indicated by the formula Nb(1+x)Se2 the solid solution takes place by addition of niobium atoms as the Nb content increases from Nb1.00Se2 to Nb1.29Se2. The crystal structure is of the NbS2 (H) type. sp. gr. P63/mmc