Comparatively Low Temperature Synthesis, Characterization and Some Physical Studies on Transition Metal Vanadates

Abstract

Pure transition metal vanadates NiV2O6 and CuV2O6 were successfully prepared via co-precipitation technique as low as at 600 °C. The crystal structure and their phase formation were confirmed by X-ray powdered diffraction. Both the compounds were identified to have a single-phase triclinic structure. The bonding characteristics were studied by FTIR spectroscopy. The temperature dependence of electrical resistivity of these vanadates shows a typical semiconducting nature of NiV2O6 and CuV2O6, consistent with their electronic band structures. The calculated band gap energy values of NiV2O6 and CuV2O6 were found to be 2.42 and 2.0 eV respectively, employing a DRS UV-Visible spectrophotometer. Magnetic susceptibility measurements and calculated Magnetic moments confirm their paramagnetic nature. The photocatalytic efficiency was investigated by photo-degradation of methylene blue (MB) solutions employing solar light and found to be promising photocatalysts.

New Solid Solution and Phase Equilibria in the Subsolidus Area of the Three-Component CuO–V2O5–Ta2O5 Oxide System

“…The IR spectrum of CuV 2 O 6 comprised two broad absorption bands with maxima at 864 and 550 cm −1 ( Figure 2 , curve a). The absorption band with a maximum at 864 cm −1 can be ascribed to stretching vibrations of V-O bonds in distorted VO 6 octahedra (characteristic for CuV 2 O 6 structure) [ 48 , 50 ]. IR spectra of solid solution CuTa 1.70 V 0.30 O 6 (x = 0.30), ( Figure 2 , curve b), and its matrix CuTa 2 O 6 ( Figure 2 , curve c) contains four bands in the boundaries of 950–850 cm −1 , 750–550 cm −1 , 520–430 cm −1 and 380–300 cm −1 with maxima at about 890, 640, 460 and 330 cm −1 .…”

“…IR spectra of solid solution CuTa 1.70 V 0.30 O 6 (x = 0.30), ( Figure 2 , curve b), and its matrix CuTa 2 O 6 ( Figure 2 , curve c) contains four bands in the boundaries of 950–850 cm −1 , 750–550 cm −1 , 520–430 cm −1 and 380–300 cm −1 with maxima at about 890, 640, 460 and 330 cm −1 . It follows from the literature survey that these bands are characteristic of solid tantalates (V) and vanadates (V) [ 48 , 50 , 51 , 52 , 53 ]. The similarity of these IR spectra corroborates that the solid solution adopts the CuTa 2 O 6 structure.…”

“…An intensive band with an absorption maximum registered in the region 950–850 cm −1 at ~870 cm −1 can be attributed to the stretching vibrations of Ta-O and V-O bonds in distorted TaO 6 and TaO 7 as well as VO 4 and VO 6 polyhedra [ 48 , 49 , 51 , 52 , 54 ]. Bands in the range of 750 to 550 cm −1 and 520–430 cm −1 can be attributed to the stretching vibrations of the Cu-O bonds in the distorted CuO x polyhedra [ 45 , 46 ] and the stretching vibrations of M-O (M = Ta, V) bonds in the moderately distorted MO 7 , MO 6 and VO 4 polyhedra [ 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. The bands registered in the range of 350 to 330 cm −1 can be attributed to bending vibrations of the O-M-O bridges (M = Cu, Ta, V), or they are of mixed character [ 48 , 49 , 50 , 53 ].…”

“…Bands in the range of 750 to 550 cm −1 and 520–430 cm −1 can be attributed to the stretching vibrations of the Cu-O bonds in the distorted CuO x polyhedra [ 45 , 46 ] and the stretching vibrations of M-O (M = Ta, V) bonds in the moderately distorted MO 7 , MO 6 and VO 4 polyhedra [ 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. The bands registered in the range of 350 to 330 cm −1 can be attributed to bending vibrations of the O-M-O bridges (M = Cu, Ta, V), or they are of mixed character [ 48 , 49 , 50 , 53 ].…”