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In the vision of hyperthermia application, high quality superparamagnetic MnFe2O4 nanoparticles (NPs) were synthesized via low cost and environment-friendly co-precipitation method. Thermogravimetric and differential thermal analysis studies confirmed the ferritization temperature at 900 °C. The formation of crystals with a single-phase cubic spinel structure with the Fd3m space group has been confirmed by XRD analysis. SEM-EDX result reveals that the spherical nature of grains with some agglomeration and elemental analysis helps to calculate the atomic percentage of each detected element. An average particle size (∼25 nm) was determined by TEM analysis. VSM analysis shows that saturation magnetization (Ms) increases with decreasing temperature in the range 54.18–59.67emu/g at room temperature (300K) to low temperature (5K), respectively, which displays temperature change affects the saturation magnetization and coercivity. FC-ZFC measurements indicated a blocking temperature of NPs around 97.17K. The induction heating study was performed on MnFe2O4 magnetic NPs at 4 kA/m AC magnetic field amplitude and 280 kHz frequency for application in magnetic hyperthermia. The result demonstrates that the heating ability of MnFe2O4 magnetic NPs can be achieved hyperthermia temperature (42 °C) at small content of 0.4 g/mL within 260sec-time duration, which confirms that the prepared material can be used as a heating agent in magnetic hyperthermic treatment. The specific absorption rate (SAR) was found at 217.62 W/g, the obtained result is superior to the previous reports. The obtained results show that the newly synthesized superparamagnetic NPs can act as a promising candidate for hyperthermia therapy due to its high heat-generating capability at lower concentrations with less time period.

Dy3+ incorporated yttrium iron garnet (Y3-xDyxFe5O12) nanoparticles were fabricated via self-combustion assisted solution gelation route. The mono-phase formation and nanocrystalline nature of the fabricated samples were confirmed through X-ray employed diffraction studies. It demonstrates mono phasic garnet-cubic-spinel lattice formation along with an average particle size varying between 6 and 9 nm. The lattice constant determined via XRD analysis is found within the scope of 12.356 A to 12.424 A. The morphological aspects were visualized by the SEM analysis which uncovered the spherical shaped nature of grains with the size in nanometer range. The compositional verification was undertaken with the help of EDAX analysis which ensured the presence of elements in desired proportions. The magnetic parameters were diminished with Dy3+ content x while the magneton number nB increased with increasing Dy3+ content x. The electrical properties were measured using ‘two probe technique’ with varying temperature. The electrical resistivity diminishes with increment in temperature demonstrating semiconducting conduct. Values of various dielectric parameters show strong frequency dependence. With the increase in frequency, the dielectric parameters get decreases within the scope of 104 Hz–106 Hz. The magnetic, electrical and dielectric conduct of these prepared nanoparticles show its relevance in high frequency device development applications.

Nano-spinel zinc ferrites (ZnFe2O4) with substitution of diamagnetic magnesium (Mg2+) ions were synthesized using solution-gelation (sol-gel) self ignition route. The thermal, structural, spectral, optical and N2-physisorption properties of the prepared Zn–Mg ferrite nanoparticles were analyzed by standard characterization techniques. The temperature dependent spinel phase formation and percentage weight loss was studied by thermogravimetric and differential thermal analysis (TG-DTA). The analysis of the room temperature X-ray diffraction (XRD) patterns showed the formation of cubic spinel structure with single phase in the Zn–Mg ferrites. The crystallite size decreasing from 27 nm to 20 nm with Mg2+ substitution confirmed the nanocrystalline formation of the Zn–Mg ferrites. The two characteristics vibrational modes of interstitial sub-lattice sites corresponding to the spinel structure were observed within the desired wavelength range of the FT-IR spectra. The optical band gap values estimated from the UV–Visible data analysis is found to be in the scope of 1.96 eV–2.39 eV. The photoluminescence (PL) spectra showed the broader emission band in the visible region (around 525 nm) for all the samples of Zn–Mg ferrites. The BET isotherms were recorded by the N2 adsorption-desorption and the surface area, pore volume, average pore radius etc surface parameters were deduced. The BET surface area and average pore radius values were obtained in the range of 5.6–24.8 m2/gm and 2.61–4.52 nm respectively.

Nanoscale spinel zinc ferrite (ZNF) was prepared by sol-gel auto-ignition route and subsequently its surface was modified by oleic-acid (OA) coating. The pristine and surface modified ZNF nanoparticles (UC-ZNF and OA-ZNF) were characterized by standard techniques. XRD patterns of both the samples ensured the nanocrystalline mono-phasic cubic-spinel lattice structure with ‘Fd-3m space-group’. FT-IR spectra revealed the presence of vibrational frequency-modes of spinel structure and successful coating of OA over ZNF. The nano-size spherical grains with some agglomeration and OA coating over ZNF were visualized in FE-SEM images. The hydrophobic-to-hydrophilic surface-transition of ZNF was confirmed by water contact-angle measurements. The BET surface-area and distribution of pore-radius was evaluated by recording N2-isotherms. The M − H plots confirmed the superparamagnetic nature of both the samples. Optical properties were studied by UV–Vis and PL spectroscopy techniques. The colloidal-stability and distribution of particle-sizes were estimated by zeta-potential and DLS measurements. Magnetic hyperthermia studies were carried out for different concentrations (2, 4, 6, 8 and 10 mg/mL) of both the samples. The biocompatible nature of both the samples was studied by cell-viability studies. All these results ensure the implementation of OA-ZNF nanoparticles with minimum dose rate (8 mg/mL) in magnetic hyperthermia therapies for cancer treatment.