Synthesis and characterization of high-quality polycrystalline sample NiV$_2$O$_6$ by solid-state reaction technique

Employing the solid-state reaction route, good quality polycrystalline sample NiV$_2$O$_6$ is prepared that has effective application in rechargeable Li-ion batteries. The raw materials NiO and V$_2$O$_5$ (purity $>$ 99%) were used for the fabrication of NiV$_2$O$_6$. The phase formation and thermal stability of this sample were measured by thermogravimetric analyzer. The micro-structural feature of this sample was measured by scanning electron microscopy (SEM). The SEM images ensured that the product NiV$_2$O$_6$ is very uniform and well-separated and consists of large grain size of about 1–5 $\mu$m. The crystal structure and bonding characteristics of NiV$_2$O$_6$ were obtained by XRD diffractometer and FTIR spectroscopy. The X-ray diffraction data revealed the triclinic structure of NiV$_2$O$_6$ with space group P-1 and lattice parameters: $a$ = 7.162 $\mathring{\mathrm{A}}$, $b$ = 8.816 $\mathring{\mathrm{A}}$, $c$ = 4.789 $\mathring{\mathrm{A}}$, and axial angles $\alpha$ = 90.13$^\circ$, $\beta$ = 93.78$^\circ$, and $\gamma$ = 101.72$^\circ$. The temperature-dependent electrical resistivity of NiV$_2$O$_6$ was measured by two-probe method which ensured the semiconducting nature of this phase. The electronic and optical properties were investigated by impedance analyzer and UV-Visible spectrophotometer. The calculated optical band gap of NiV$_2$O$_6$ is found to be 2.38 eV.