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In the present research work, the sol–gel auto-combustion preparation method using two different fuels agents (citric acid and glycine) was used to synthesize CoFe2O4 nanoparticles. The structural and morphological studies were performed to confirm the ability to obtain a pure cubic spinel phase with a particle size < 100 nm. The particle size effects on structural, Raman and magnetic properties of the CFO was studied to confirm that the glycine fuel decreased the particle size and the saturation magnetization. The CoFe2O4 nanoparticles were found to exhibit a considerable value of maximum energy product (BH)max, which makes them good candidate for permanent magnet applications. Notably, the cytotoxic activity of both prepared compounds against two different human breast cancer cells (T47-D and MDA-MB-231) and one prostate cancer cell (PC3) were evaluated. Both C1 and C2 compounds are quite cytotoxic against the human breast and prostate cancer cells and the C2 with lower particle size was found to have the higher cytotoxic potency (minimum viability values) with 49%, 39% and 19% in MDA-MB-231, PC3 and T47-D cancer cells, respectively. The cytotoxicity against normal human cells was found to be lower than 3% even for high C2 particle concentrations, reflecting the human-safe-and-friendly nature of the CoFe2O4. [ABSTRACT FROM AUTHOR]

In this paper, we have investigated the structural, electrical, and dielectric properties of Ni0.1Co0.5Cu0.4Fe2-xCrxO4 (x = 0 and 0.3) ferrites. Samples have been prepared by employing the sol–gel method. The X-ray diffraction data along with Rietveld refinement were used to assess the phase purity and the structural parameters of samples. The morphology and the grain size of the prepared ferrite nanocrystals were observed with scanning electron microscopy. At room temperature, the Raman spectra displayed active phonon modes. FTIR spectra revealed two principal absorption bands due to the stretching vibration of metal oxygen in tetrahedral and octahedral sites. With increasing of Cr3+ concentration, both Raman and FTIR spectra showed that all modes shifted to higher wavenumbers. The dielectric properties were investigated using impedance complex spectroscopy in the frequency region (100‒106 Hz) at different temperatures. The ac-conductivity for both studied compounds was well analyzed using the augmented Jonscher equation. The plots of both imaginary part of permittivity (ε″) and dielectric loss (tanδ) vs. frequency, exhibit a dielectric dispersion in our compounds at low frequencies. This is described according to the Maxwell–Wagner model in agreement with Koop's theory. The modulus curve was used to interpret the relaxation behaviors of charge carriers. The Nyquist plots of impedance for both samples have been modeled using the same equivalent circuit which is formed by a three-element R-CPE connected in series. [ABSTRACT FROM AUTHOR]