Hydrothermal synthesis of NiFe2O4 nano-particles: structural, morphological, optical, electrical and magnetic properties

NiFe2O4 nano-crystallites with an average diameter of 8.9 nm are synthesized via hydrothermal method. The single-phase spinel structure is confirmed from X-ray diffractograms. Morphology is analysed by transmission and field emission scanning electron microscopes. High specific surface area of 55.7 m2 g−1 is obtained for nano-particles. The M– H loop and M– T curve behaviours are investigated by vibrating sample magnetometry. The optical band gap energy is estimated from the UV–visible spectrum. In addition, the frequency dependence of dielectric properties is investigated. Cole–Cole plots are drawn to study electrical conduction mechanism and the kind of relaxation—Debye or non-Debye type. Low a.c. conductivity and low magnetic losses are noticed at 5 MHz frequency, which are suitable for microwave device applications.