Copper doped nickel ferrite nanoparticles: Jahn-Teller distortion and its effect on microstructural, magnetic and electronic properties

摘要

Samples with empirical formula Ni_(1-x)Cu_xFe_2O_4 (x = 0.00, 0.25, 0.50, and 1.00) were prepared using chemical route. All the samples showed single spinel phase without any impurity. Average crystallite sizes were observed in the range of 12 nm to 39 nm as calculated by using Williamson-Hall (W-H) graphs. Raman spectra of all samples confirmed the lowering of crystal symmetry of octahedral sublattices with increasing Cu content. Signature of Jahn-Teller distortion due to substitution of Cu~(2+)(3d~9) ions was detected using Raman spectros-copy. Absorption spectra of all the samples were recorded using UV-Vis spectroscopy, which confirmed the opaque character near red and infrared (IR) region. Onset of superparamagnetic behaviour has been observed by incorporating Cu~(2+) in the nickel ferrite with the mean blocking temperatures for all samples well below 300 K. Dielectric studies revealed that the grain boundaries played a major role in controlling the properties with increase in Cu~(2+) percentage.