Nanocrystalline Ni_(0.70-x)Cu_xZn_(0.30)Fe_2O_4 with 0≤x≤0.25 prepared by nitrate-citrate route: structure, morphology and electrical investigations

摘要

AbstractThe structure, morphology, temperature dependent electrical and frequency dependent dielectric behavior of Cu2+substituted Ni–Zn spinel ferrite nanoparticles having generic formula Ni0.70−xCuxZn0.30Fe2O4(x = 0.00, 0.05, 0.15 and 0.25) prepared by sol–gel auto combustion technique with citric acid as a chelating agent is reported here. The XRD patterns revealed the presence of cubic spinel structure. The crystallite size was obtained using Scherrer’s formula which varies between 29 and 34 nm. The lattice parameter was found to increase with an increase in copper concentration. FTIR spectra show the characteristic bands for tetrahedral and octahedral sites. The morphology investigated by SEM technique demonstrates the nanocrystalline grain formation with almost spherical geometry. The grain size obtained from SEM analysis is in the range of 69–88 nm. The particle size obtained through TEM image analysis varies from 30 to 35 nm. The electrical and dielectric behavior was studied using a two-probe technique as a function of temperature and frequency respectively. Various electrical parameters like DC resistivity, activation energy, drift mobility, charge carrier concentration, diffusion coefficient were obtained as a function of copper concentration ‘x’. Arrhenius plot indicates the semiconducting nature of Cu2+substituted Ni–Zn spinel ferrite. The dielectric constant and dielectric loss tangent both decreases with increase in frequency and concentration of Cu2+.