Synthesis, photoluminescence and magnetic properties of barium vanadate nanoflowers

The flower-shaped barium vanadate has been obtained by the composite hydroxide mediated (CHM) method from V₂O₅ and BaCl₂ at 200 °C for 13 h. XRD and XPS spectrum of the as-synthesized sample indicate it is hexagonal Ba₃V₂O₈ with small amount of Ba₃VO_4.8 coexistence. Scan electron microscope and transmission electron microscope display that the flower-shaped crystals are composed of nanosheets with thickness of ∼20 nm. The UV-visible spectrum shows that the barium vanadate sample has two optical gaps (3.85 eV and 3.12 eV). Photoluminescence spectrum of the barium vanadate flowers exhibits a visible light emission centered at 492 and 525 nm which might be attributed to VO₄ tetrahedron with T_d symmetry in Ba₃V₂O₈. The ferromagnetic behavior of the barium vanadate nanoflowers has been found with saturation magnetization of about 83.50 × 10⁻³ emu/g, coercivity of 18.89 Oe and remnant magnetization of 4.63 × 10⁻³ emu/g, which is mainly due to the presence of a non-orthovanadate phase with spin S = 1/2.