http://depot.umc.edu.dz/handle/123456789/13379 2026-05-01T04:47:01Z http://depot.umc.edu.dz/handle/123456789/13544 Influence of green surfactant on particle size and optical properties of hematite nanoparticles (α-Fe2O3) Zine, A.; Chetibi, L.; Sobti, N.; Hamana, D.; Achour, S. As an n-type semiconductor, hematite (α -Fe2O3) has attracted a great deal of attention from researchers in different fields because of its nontoxicity, low cost, high stability under ambient conditions, and multiple functions. It has been intensively investigated for different applications such as lithium batteries [1, 2], sensors [3], catalysts, [4] pigments [5] and so on. In this work, hematite nanoparticles are prepared by a simple green method at low temperature (polyol) using Fe(NO3)3-6H2O as a reagent (0.6M), olive leaves extraction as a surfactant and distilled water as a solvent. In order to understand the influence of the extract solution of olive leaves, α-Fe2O3 powders has been characterized by XRD Pattern, UV-Visible spectroscopy and FTIR measurements and SEM. The variation of the extract olive leaves concentration reveals a decrease of the particle size and an enhancement of the optical properties of these nanoparticles 2016-12-15T00:00:00Z http://depot.umc.edu.dz/handle/123456789/13543 Preparation process of a highly resistantanorthite based ceramics using local raw materials: Effect of Na2CO3 additions on sintering and crystallization Zaiou, S.; Harabi, A. Anorthite (CaO·Al2O3·2SiO2) is mainly used for traditional ceramics. In this study, anorthitebased ceramics was obtained by solid state reaction.The new selected composition was80 wt.% kaolin (DD2 type) and 20 wt.%calcium oxide (CaO) extracted from CaCO3. The choice of these raw materials was dictated by their natural abundances. Moreover, different amounts of Na2CO3(0.5-3.0 wt.% ) have been added in order to promote densification and lower down its sintering temperature. Optimizing the main parameters controlling anorthite based ceramics production such as milling techniques, compacting pressure, sintering temperature and holding time may lead to better anorthite based ceramics. The prepared samples were sintered at different temperatures ranging between 800 and 1100 °C for 1 h. A relative density of about 97% of the theoretical was reached for samples containing 3 wt.%Na2CO3 sintered at 1000 °C for 1 h. A porosity ratio of about 4% for samples containing 3 wt.%Na2CO3 sintered at 1000°C for 1 h.Finally, these fabricated products were also characterized byscanning electron microscopy, X-ray diffraction andRaman spectroscopy 2016-12-15T00:00:00Z http://depot.umc.edu.dz/handle/123456789/13542 Dielectric and electrical proprieties of Nano-TiO2 powders and thin films doped by copper at room temperatures Toubal, B.; Bensaha, R. In this work, we have made a parallel study using both powders and thin layers of TiO2 doped by copper (Cu). Annealing temperatures effects and the Cu dopant concentration on the phase composition, chemical banding and microstructure were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy (TEM) and Atomic force microscopy (AFM). Both the dielectric properties of Cu doped TiO2 powders and the electrical resistivity of the films were acquired at room temperatures. The details outcome from XRD and Raman spectroscopy display that only the anatase TiO2 crystallization has been obtained for both films and powders as a function of annealing temperature and the Cu addition. Both the Impedance Spectroscopy and Nyquist diagrams Curves of Cu doped TiO2 were obtained at room temperature. The electrical resistivity (ρ) was found decreasing from 4.5 1011 to 8.7 1010 with the annealing temperature and the Cu addition 2016-12-15T00:00:00Z http://depot.umc.edu.dz/handle/123456789/13541 A Study of the structural and electronic properties of LaX (X=Se, Te ) in two phases B1, B2 ander high pressure Soltani, F.; Baaziz, H.; Charifi, Z. The objective of this work is a study of the structural properties (lattice parameters, total energy, bulk modulus) and electronic properties (band structure, density of states) of rare earth monochalcogenides LaX (X=Se, Te) under ambient and high pressure in two phases : the face centred cubic structure type B1(NaCl) and the simple cubic structure type B2 (CsCl) were investigated(1) with the full potential linearized plane wave (FP-LAPW) methode implemented in Wien2K code, based on density functional theory (DFT)(2). The exchange-correlation term is calculated with generalized gradient approximation(3) and local density approximation(4). The equilibrium lattice parameters, bulk modulus B and the minimal energy are investigated and compared with the previous theoretical and experimental data, we have also determined the band structure, total density of states and the electron charge density. Our results are in reasonable agreement with the available theoretical and experimental data in the litterature 2016-12-15T00:00:00Z