Nanoparticles of Zn substituted lithium ferrite (Li0.31Zn0.38Fe2.31O4, LZFO) synthesized by the sol-gel route are successfully dispersed in layers of reduced graphene oxide (RGO) during the course of preparation. The analysis of X-ray diffractograms confirms the desired crystallographic phase of the nanocomposite sample of LZFO-RGO. The results of field emission scanning electron microscopy and high resolution transmission electron microscopy are consistent with the presence of dispersed nanoparticles in different layers of graphene oxide. Structural information obtained from selected area electron diffraction and nanocrystalline fringe patterns agree well with those obtained from X-ray diffractogram analysis. Mössbauer spectra recorded at 300 and 77 K suggest the presence of a fraction of superparamagnetic particles together with ferrimagnetic particles. Static magnetic measurements include observation of hysteresis loops at 300 and 5 K, magnetization vs. temperature curves under zero field cooling and field cooling conditions. Saturation magnetizations, coercive field, and saturation to remanence ratio are also evaluated. To explore the suitability of this nanocomposite for hyperthermia application, inductive heating of LZFO and LZFO-RGO is measured at different concentrations of nanoparticles. Interestingly, the inductive heating rate of LZFO nanoparticles is enhanced in the nanocomposite phase of LZFO-RGO, suggesting their high potential for hyperthermia therapy in cancer treatment.
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.
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