Structural, dielectric and ac electrical properties of nano-structured Mn0.6Co0.2Ni0.2Fe2O4 ternary ferrite synthesized by citrate-gel auto-combustion technique

Abstract

The present paper reports the structural, dielectric and ac electrical properties of nanoparticles of mixed polycrystalline spinel ferrite ternary compound Mn0.6Co0.2Ni0.2Fe2O4 synthesized by using the citrate-gel auto-combustion technique. The standard characterization techniques such as EDAX, XRD and FTIR were primarily employed to confirm the elemental stoichiometry, crystallized single-phase, IR-functional groups. These measurements ascertained the formation of monophasic and pure ferrite compound. The powder X-ray diffraction analysis was done to determine the lattice constant(0.8420 nm), crystallite size(21 nm), X-ray density (5.16 g/cm3), distribution of cations among the tetrahedral and octahedral sites of spinel lattice(with iron-Fe3+ distribution ratio among A and B sites is 0.25), bond angles and bond lengths. The theoretical lattice constant is found to be 0.8422 nm. The nature and position of the IR-bands were observed through FTIR spectroscopy. The high-frequency band v1 (A-site vibrations) lies at 563.07 cm-1 while the low-frequency band v2 (B-site vibrations) lies at 462.59 cm-1 . The force constants for the tetrahedral site (kt) and octahedral site (ko) were deduced 1.33×102 N/m and 1.27× 102 N/m, respectively. Frequency dependence of dielectric constant and tangent loss has been explained by the Maxwell Wagner model and Koop's theory. The Jonscher’s power low was used to describe the ac conductivity measurements. The Nyquist and cole-cole plots indicated presence of grain contribution in the conduction mechanism.