Synthesis and characterizations of highly crystallized α′-NaV2O5 needles prepared by a hydrothermal process

Abstract: Highly crystallized α′-NaV2O5 needles were prepared by a simple hydrothermal process. X-ray diffraction showed that the material had an orthorhombic structure. Scanning electron microscopy and high-resolution transmission electron microscopy confirmed that the α′-NaV2O5 needles were fabricated along the 〈010〉 axis. The local structure of the material was studied by Raman scattering. X-ray photoelectron spectroscopy confirmed that the oxidation state of vanadium of the material was +4.5. The formation mechanism of α′-NaV2O5 crystals depended on the hydrothermal conditions. Highly crystallized α′-NaV2O5 needles could be obtained with the presence of F−, while α′-NaV2O5 sheets were obtained without F− or in the presence of other haloid anions such as Cl− and Br−. [Copyright &y& Elsevier]