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.

Dynamics of silver ions in AgI doped Ag2O-SeO2-MoO3 mixed former glasses.

We have studied the dynamics of silver ions in AgI-doped Ag2O-SeO2-MoO3 mixed former glasses in wide frequency and temperature ranges. We have observed that the ionic conductivity exhibits a mixed glass network former effect for low AgI content. The scaling for the conductivity spectra shows that the mechanism of charge carrier dynamics is independent of temperature and composition. We have obtained a mobile Ag+ ion concentration from the Nernst-Einstein relation, which is found to be independent of temperature, but slightly dependent on composition. We have also obtained the characteristic mean square displacement of the silver ions from the mapping of the conductivity spectra in the time domain. It is observed that the composition dependence of the characteristic displacement is opposite to that of the conductivity. We have also studied the influence of the network structure of these glasses on ion dynamics using infrared spectra and established a correlation between the ion dynamics and the SeO32- structural units. It is observed that the available hopping sites for Ag+ ions increase in the glass network with the increase of non-bridging oxygens of SeO32- units.