Samir Guermazi

This work deals with the physical investigations on Zn-doped TiO₂ synthesized via a solvent controlled non-aqueous sol–gel route. X-ray diffraction analysis indicated that TiO₂ particles crystallized in both tetragonal anatase and rutile structures. FTIR analysis confirmed the insertion of Zn in TiO₂ network, and revealed the presence of surface defects in the prepared powders, as proved by their porous morphologies. UV-visible absorption was performed to provide an insight into the band-gap variation in the Zn-doped TiO₂ nanopowders as a function of Zn doping. On the other hand, the electrical properties were studied using complex impedance spectroscopy in the frequency range from 40Hz to 1MHz at temperature range 480-600K. The impedance plots are well fitted to an (R₁//C₁)-(R₂//CPE₁) equivalent circuit. As well, the correlated barrier hopping model (CBH) was proposed to describe the conduction mechanism. Finally, Photocatalytic activities of the Zn doped TiO₂ nanoparticles were evaluated via the degradation of the rhodamine B (RhB) dye under UV light irradiation. The results showed enhanced performance by Zn-doping, compared to the undoped TiO₂ nanoparticles.

In this paper, Fe₂(MoO₄)₃ (FMO) powders have been synthesized via an easy precipitation approach. The microstructural properties of the synthesized product were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Two FMO samples, 1 and 2, were synthetized using two reactants, sodium molybdate and ammonium heptamolybdate, respectively. In both cases, pure monoclinic structure with space group P2/a has been identified, via XRD measurements. The crystallite sizes, estimated from Scherer’s formula, are of (38 ± 2) and (46 ± 4) nm according to the precursor used. Besides, the sample 1 showed a relatively larger specific surface area of 42.77 m²/g, than the sample 2 with 35.28 m²/g. The EDS microanalysis confirms the stoichiometric amount of the chemical elements. The SEM micrographs reveal a regular distribution of particles shape that presented grain size of order of (192±52) nm for sample 1. While, the sample 2 presents grains of (215±59) nm size, with a less regular shape.