Novel magnetic nanohybrids composed of nanomaghemite covered by organic molecules were successfully synthesized at room temperature with different functionalization agents (sodium polystyrene sulfonate, oxalic acid, and cetyltrimethylammonium bromide) in low and high concentrations. Structural, vibrational, morphological, electron energy-loss spectroscopy, magnetic, and Mössbauer characterizations unraveled the presence of mainly cubic inverse spinel maghemite (γ-Fe2O3), whilst X-ray diffraction and 57Fe Mössbauer spectroscopy showed that most samples contain a minor amount of goethite phase (α-FeOOH). Raman analysis at different laser power revealed a threshold value of 0.83 mW for all samples, for which the γ-Fe2O3 to α-Fe2O3 phase transition was observed. Imaging microscopy revealed controlled-size morphologies of nanoparticles, with sizes in the range from 8 to 12 nm. Organic functionalization of the magnetic nanoparticles was demonstrated by vibrational and thermogravimetric measurements. For some samples, Raman, magnetic, and Mössbauer measurements suggested an even more complex core-shell-like configuration, with a thin shell containing magnetite (Fe3O4) covering the γ-Fe2O3 surface, thus causing an increase in the saturation magnetization of approximately 11% against nanomaghemite. Field cooling hysteresis curves at 5 K did not evidence an exchange bias effect, confirming that the goethite phase is not directly interacting magnetically with the functionalized maghemite nanoparticles. These magnetic nanohybrids may be suitable for applications in effluent remediation and biomedicine.

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Glasses containing metallic nanoparticles are promising materials that should also possess the best spectroscopic, chemical, mechanical and thermal characteristics for technological applications in optics and photonics. For this reason it was chosen to synthesize and characterize the pure silver doped borosilicate glasses and silver nitrate. The present work investigates the generation of silver nanoparticles on the surface and the mass of a borosilicate glass in which it was directed to the synthesis process in which it was consisted: in the stoichiometric calculations, in the determination of the melting temperature, in the choice of reagents with high degree of purity, in the manufacture of the samples, in the appropriate polishes and in the determination of heat treatments close to Tg of the glass in question. From this phase, the research followed the application of techniques of differential thermal analysis (ATD) and transmission electron microscopy (MET). Thus, from the results and analyzes obtained, it was possible to observe that the borosilicate glass samples of this work will obtain satisfactory experimental results, in which it was possible to prove its optical and structural properties similar to those recognized in literature, thus making it a promising material in area of vitreous materials applied to nanotechnology borosilicate glasses are obtained from the combination of silicon dioxide (SiO2) with boron oxide (B2O3) and the resulting samples were annealed at various temperatures. Due to the structural shape, these glasses have a high resistance to thermal shock, good chemical durability and excellent electrical resistivity compared to other glasses on the market today. Therefore, based on these important structural, physical and chemical characteristics and also in the variety of applications, this study was chosen for the synthesis and characterization of pure borosilicate glass and doped with silver nitrate. We verified the formation of silver nanoparticles, after the heat treatment, by transmission electron microscopy.

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