Electrical and magnetic properties of Nb2O5-δ crystallographic shear structures

The reduced niobium oxides Nb{sub 25}O{sub 62}, Nb{sub 47}O{sub 116}, Nb{sub 22}O{sub 54}, and Nb{sub 12}O{sub 29} have been prepared in pure polycrystalline form by a niobium-metal gettering technique. They are related to the high niobia parent structure through the action of cystallographic shear to accommodate oxygen deficiency in Nb{sub 2}O{sub 5{minus}{delta}}. Electrical conductivities increase with increasing reduction: Nb{sub 12}O{sub 29} is a metallic conductor down to 0.3 K. All show, surprisingly, Curie-Weiss behavior in the {chi}-vs-{ital T} curves, with Nb{sub 12}O{sub 29} ordering antiferromagnetically at 12 K.