Controlled growth of β-Na _0.24V ₂O ₅ nanowire thin films

A method to prepare well-aligned β-Na _0.24V ₂O ₅ nanowires (NWs) involves the deposition of a vanadium oxide complex onto a substrate via gaseous transport, followed by a reaction between the complex and a sodium cation (Na ⁺) precursor coated on the substrate. Techniques to investigate the composition, crystallinity, and morphology of products as prepared include ICP-AES, X-ray powder diffraction (PXRD), SEM/transmission electron microscope (TEM), and XPS. PXRD patterns and images from a TEM confirm the single-crystalline nature of β-Na _0.24V ₂O ₅ NWs, which grow along direction [1 0 0]. Factors affecting the amount of deposited material and morphology were tested. On varying the reaction conditions, the length of the β-Na _0.24V ₂O ₅ wires is controlled in a range of 5-25 lm. A mechanism of formation is proposed. According to measurements of field emission, the turn-on field is 7.8 V/lm, and the maximum emission current density of 4.66 mA/cm ² occurs at field 11 V/μm. This method is applicable to grow other tertiary metal oxide nanostructures on glass substrate.