Structure and properties of layered perovskite compounds [Sr2VO4−δ]

The effects of the oxygen deficiency on the electrical and magnetic properties of Sr 2 VO 4− δ were investigated. Single-phase samples of polycrystalline Sr 2 VO 4− δ with δ =0.18, 0.29 and 0.38 were synthesized by the solid state reaction in flowing hydrogen atmosphere. The crystal structure was determined by Rietveld analysis of X-ray diffraction data. All the samples were tetragonal at 298 K. With increase of δ, the lattice constant ‘a’ decreased and the lattice constant ‘c’ increased. Electrical resistivity measurements showed that all the samples were semiconductive with resistivity of about 1Ωcm at 298 K. Magnetic measurements showed that the magnetic properties of Sr 2 VO 4− δ system were strongly dependent on the oxygen deficiency δ. It was suggested that the non oxygen-deficient compound Sr 2 VO 4 ( δ =0) had no magnetic long-range order. As δ was increased, spin-glass-like behavior became evident at low temperatures and was overlapped by a long-range magnetic order with a transition temperature of ∼ 35 K for δ ≧ ∼ 0.2 . It was suggested that the long-range magnetic order was a canted antiferromagnetism with a small net magnetization.