Impact of Jahn Teller ion on magnetic and semiconducting behaviour of Ni-Zn spinel ferrite synthesized by nitrate-citrate route

Abstract Copper substituted Ni 0.70-x Cu x Zn 0.30 Fe 2 O 4 (x = 0.0, 0.10 and 0.20) spinel ferrite nanoparticles were prepared by using sol-gel auto combustion method to understand the influence of copper compositional variation on the structure, morphological, magnetic, and electrical properties of Ni-Zn spinel ferrite. XRD pattern reveals that the samples are crystallized in single phase cubic spinel structure. Using XRD data various structural parameters were obtained. The lattice constant increases with increasing copper content. The particle size obtained by FWHM of most intense peak using Scherer's formula confirms the nanocrystalline nature of the prepared samples. Analysis of SEM images shows the agglomeration of particles with spherical geometry. The elemental compositional details probed by EDS were well matched with that of the calculated composition of each atom. The average particle size estimated using TEM was in the range of 30 nm and 26 nm for NCZ-1 and NCZ-3 respectively. The SAED pattern shows the cubic structure of the NiCuZn spinel ferrites. The Raman spectra auxiliarily confirmed the formation of cubic spinel structure. The magnetic behaviour of all samples was studied at room temperature using pulse field hysteresis loop tracer technique. All the samples exhibit a typical hysteresis loop with increasing saturation magnetization and decreasing coercivity with substitution of copper ions. The magnetic behaviour of these samples was explained on the basis of Neel's collinear model. The DC electrical resistivity measured by two probe technique shows the semiconducting behaviour. The carrier concentration, drift mobility, activation energy were obtained using DC electrical resistivity data and correlated with copper substitution. The experimental data obtained from the various measurements is correlated and influence of copper substitution in Ni-Zn spinel ferrite is discussed in detail.