Abstract
Nano-nickel ferrites defected by vanadium doping (NiV
x
Fe
2−1.67
x
O
4
, 0 ≤
x
≤ 0.25) were prepared using a simple sol gel method. Rietveld analysis revealed a nonmonotonic change in lattice parameter, oxygen parameter and magnetization upon doping with vanadium. Cation distributions suggested from either Rietveld analysis or from experimental magnetic moments were in a good agreement. For low doping values (
x
= 0.05), vanadium was residing mainly in octahedral sites, while for samples with vanadium content (
x
≥ 0.1) a significant part of vanadium ions resided at tetrahedral sites; a result which has been confirmed by the analysis of Fourier-transform infrared (FTIR) spectrums obtained for the samples. The transmission electron microscope (TEM) image showed fine spherical particles with size of ∼ 11 nm. All samples showed a superparamagnetic nature with a nonmonotonic change of either magnetization (
M
S
) or coercivity
(H
C
) with the content of nonmagnetic V
5+
. The cation occupancies indicated presence of an enormous number of vacancies through doping with high valence cation V
5+
, making present samples potential electrodes for Li- or Na-ion batteries.