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The aim of this paper was the syntheses and characterizations of functionalized zeolite materials with undoped and nitrogen-doped TiO2 nanocrystals. These materials were obtained by using alternative methods, namely sol-gel and hydrothermal, directly from precursors. The synthesis of TiO2 by sol-gel and hydrothermal methods was achieved in order to compare the crystalline structures and morphologies of TiO2 on the surface of the zeolite within the obtained hybrid materials. The obtained materials were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), and scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDAX). The XRD results revealed that the natural zeolite used for the synthesis is mostly clinoptilolite and the anatase form of TiO2 for both applied methods. As it was desired, no the rutile phase of TiO2 was evidenced. The surface morphology observed by SEM analysis showed that TiO2 (spherical form) nanocrystals were attached on the zeolite surface. Therefore, the IR spectra confirmed the presence of TiO2 in to the zeolite lattice. The presence of the nitrogen ion in the materials obtained by both synthesis methods was also confirmed by EDAX spectra.

Cobalt ferrite is characterized by a partial inverse spinellic structure, which makes it a material with special magnetic properties that vary as a function of the cobalt concentration. The special magnetic properties represent one of the parameters due to which cobalt ferrite is of a great interest. In the present paper, we studied these properties from the perspective of the effect produced by the precursors of CoxFe3-xO4 nanomaterial synthesis on magnetic properties, shape, and morphology characteristics to these nanomaterials. Magnetic measurements were achieved with a SQUID magnetometer, while the structural and morphological characterization was achieved by X-ray diffraction (XRD), SEM- EDAX and AFM.

Zinc gallate (ZnGa2O4) is a normal spinel crystal structure (space group Fd3m). ZnGa2O4 has attracted much attention due its multitude of possible applications regarding field emission display, electroluminescent devices, and in the last decade mostly sensor domain. ZnGa2O4 nanoparticles were obtained by the hydrothermal method using Ga2O3 and Zn(NO3)2 x 6H2O precursors in basic medium using a Teflon-lined stainless steel autoclave tightly sealed. The synthesys was effectuated at 210°C for 4 h. The hydrothermal method is one of the most promising solution chemical methods. Thus, the size of particles and their distribution, phase homogeneity, and morphology could be well controlled. These powders were characterized by X-ray diffraction (XDR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDAX), and atomic force microscopy (AFM). Photoluminescence (PL) measurements were obtained with a conventional lamp as an excitation source.

The effect of germanium trapezoidal profile shape on the direct current (DC) current gain (βF), cut-off frequency (fT) and maximum oscillation frequency (fMAX) of silicon-germanium (SiGe) hetero-junction bipolar transistors (HBTs) has been investigated. The energy balance (EB), hydrodynamic (HD) and drift-diffusion (DD) physical transport models in SILVACO technology computer aided design (T-CAD) simulator were used. It was found that the current gain values using energy balance model are higher than hydrodynamic and much higher than those corresponding to drift-diffusion. Moreover, decreasing the germanium gradient slope towards the collector side of the base enhances the maximum oscillation frequencies using HD and EB models whilst, they remain stable for DD model.

Two samples of NaTaO3 perovskite materials were prepared by the standard hydrothermal method at the same reaction temperature (600 °C) but with different sintering times: 6 hours for sample S1 and 12 hours for sample S2.