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This work investigates the structural, magnetic and magneto-optical properties of a new zinc phosphate-tellurite glass belonging to the 45ZnO-10Al2O3-40P2O5-5TeO2 system. The glass was prepared by a wet method of processing the starting reagents followed by suitable melting–stirring–quenching–annealing steps. Specific parameters such as density, average molecular mass, molar volume, oxygen packaging density, refractive index, molar refractivity, electronic polarizability, reflection loss, optical transmission, band gap and optical basicity have been reported together with thermal, magnetic and magneto-optical characteristics. Absorption bands appear in the blue and red visible region, while over 600 nm the glass becomes more transparent. FTIR and Raman spectra evidenced phosphate-tellurite vibration modes proving the P2O5 and TeO2 network forming role. Magnetic measurements reveal the diamagnetic character of the Te-doped glass with an additional weak ferromagnetic signal, specific to diluted ferromagnetic oxides. Positive Faraday rotation angle with monotonous decreasing value at increasing wavelength was evidenced from magneto-optical measurements. The final product is a composite material comprising of a non-crystalline vitreous phase and Te-based nanoclusters accompanied by oxygen vacancies. The metallic-like Te colloids are responsible for the dark reddish color of the glass whereas the accompanying oxygen vacancies might be responsible for the weak ferromagnetic signal persisting up to room temperature.

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A facile and cheap surfactant-assisted hydrothermal method was used to prepare mesoporous cobalt ferrite nanosystems with BET surface area up to 151 m 2 /g. These mesostructures with high BET surface areas and pore sizes are made from assemblies of nanoparticles (NPs) with average sizes between 7.8 and 9.6 nm depending on the initial pH conditions. The pH proved to be the key factor for controlling not only NP size, but also the phase purity and the porosity properties of the mesostructures. At pH values lower than 7, a parasite hematite phase begins to form. The sample obtained at pH = 7.3 has magnetization at saturation M s = 38 emu/g at 300 K (54.3 emu/g at 10 K) and BET surface area S BET = 151 m 2 /g, whereas the one obtained at pH = 8.3 has M s = 68 emu/g at 300 K (83.6 emu/g at 10 K) and S BET = 101 m 2 /g. The magnetic coercive field values at 10 K are high at up to 12,780 Oe, with a maximum coercive field reached for the sample obtained at pH = 8.3. Decreased magnetic performances are obtained at pH values higher than 9. The iron occupancies of the tetrahedral and octahedral sites belonging to the cobalt ferrite spinel structure were extracted through decomposition of the Mössbauer patterns in spectral components. The magnetic anisotropy constants of the investigated NPs were estimated from the temperature dependence of the hyperfine magnetic field. Taking into consideration the high values of BET surface area and the magnetic anisotropy constants as well as the significant magnetizations for saturation at ambient temperature, and the fact that all parameters can be adjusted through the initial pH conditions, these materials are very promising as recyclable anti-polluting agents, magnetically separable catalysts, and targeted drug delivery vehicles.

Magnetite (Fe3O4) and ferrite (MFe2O4, M = Mn, Zn) hydrophobic magnetic nanoparticles with various shapes and sizes were synthesized by high-temperature reaction of organic precursor solutions. Spherical, cubic, hexagonal, and octahedral shapes and sizes ranging from 10 to 100 nm were obtained. It has been proven that the reported high capability of tailoring the shape and the size of the surface-coated nanoparticles allows controlling a variety of properties that are relevant to many potential applications. Structurally well-formed hydrophobic magnetic nanoparticles with high saturation magnetization values are reported. The hydrophobic oleic acid shell was successfully transformed by a simple and environmentally friendly oxidative scission method into azelaic acid. The morphostructural characteristics, size distributions, chemical composition, and magnetic properties of the resulting hydrophilic nanoparticles were investigated by electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, superconducting quantum interference device, and vibrating sample magnetometry. Magnetic hyperthermia measurements have been performed in a specially designed sample holder placed in an inductor with copper windings assuring alternating magnetic fields of safely biological amplitude-frequency products. The optimal shape with a specific size range for nanoparticles dispersed in various carriers providing the best heating efficiency is reported.