Magnetic Energy Morphing, Capacitive Concept for Ni0.3Zn0.4Ca0.3Fe2O4 Nanoparticles Embedded in Graphene Oxide Matrix, and Studies of Wideband Tunable Microwave Absorption.

Nanoparticles of Ni0.3Zn0.4Ca0.3Fe2O4 (NZCF) were successfully prepared by the facile wet chemical method coupled with the sonochemical method. These nanoparticles were embedded in a graphene oxide (GO) matrix (NZCFG). Rietveld analyses of X-ray diffraction, transmission electron microscope, scanning electron microscope, and X-ray photoelectron spectroscopy were carried out to extract different relevant information regarding the structure, morphology, and ionic state. A major improvement in saturation magnetization is achieved due to substitution of Ca2+ in the ferrite lattice. Interestingly, the observed value of electromagnetic absorption for a sample thickness of 1.5 mm is ∼-67.7 dB at 13.3 GHz, and the corresponding bandwidth is 5.73 GHz. The Cole-Cole plot, the Jonscher power-law fitting, and the Nyquist plot confirm the probability of improved hopping conductance and attractive capacitive behavior in NZCFG. The presence of magnetic energy morphing in combination with a higher attenuation constant, lower skin depth, and various forms of resonance and relaxation makes NZCFG the most suitable for microwave absorption.