Vanadium oxide nanotubes VOx-NTs: Hydrothermal synthesis, characterization, electrical study and dielectric properties

► Vanadium oxide nanotubes (VOx-NTs) were synthesized.
► Non-debye type of relaxation has been confirmed.
► AC conductivity exhibits two conduction mechanisms.
► DC conductivity indicated negative temperature coefficient of resistance type behavior.

Vanadium oxide nanotubes (VOx-NTs) have been synthesized via one-step hydrothermal treatment. The compounds were analyzed through X-ray powder diffraction; scanning electron microscope, UV–Visible spectroscopy, X-ray photoelectron spectroscopy (XPS) and complex impedance spectroscopy. The electrical and dielectric properties dependence on temperature (302–523 K) and on frequency (5 Hz to 13 MHz) of VOx-NTs have been reported. The complex impedance plots exhibits the presence of grain and grain boundaries. Dielectric data were analyzed using complex permittivity and complex electrical modulus for the sample at various temperatures. The presence of non-Debye type of relaxation has been confirmed by the complex modulus analysis. AC conductivity exhibits two conduction mechanisms: at high temperature, a translational motion with a sudden hopping and at low temperature, a localized hopping with a small hopping or reorientational motion. DC conductivity indicated, negative temperature coefficient of resistance (NTCR) type behavior.

The imaginary part of dielectric constant decreases with the increase in frequency at all temperatures and the values of ε′′ exhibit considerable frequency dispersion in the lower frequency range .Figure optionsDownload as PowerPoint slide