http://depot.umc.edu.dz/handle/123456789/9223 Thu, 18 Jun 2026 03:45:16 GMT 2026-06-18T03:45:16Z http://depot.umc.edu.dz/handle/123456789/14840 Contribution à l'élaboration de l'oxyde de titane par le procédé sol-gel Bouachiba, Yassine; Bouabellou, Abderrahamane The present work consists in the elaboration and the characterization of TiO2 thin films by sol-gel method. Particular attention is paid to the influence of temperatures, the annealing atmosphere, the thickness, the nature of the substrates and doping with Fe element on the different structural, morphological, optical, dielectric and chemical properties. The different samples are characterized by the X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy, FTIR spectroscopy, spectroscopic ellipsometry, UV-Visible spectroscopy, m-lines spectroscopy and hydrophilic measurements. The structural study shows that the crystallization of the films occurs for critical thicknesses. The thermal annealing under various atmospheres (air and oxygen) and the presence of buffer layers between the TiO2 film and the substrate are important factors affecting the formation and improving the structure of anatase and rutile phases. The phase transformation anatase-rutile occurs at high temperature (800°C). The SnO2 interfacial layer and the high doping level (7% at.) have the effect of decreasing the temperature of this transformation. The morphological study shows, in general, a uniform growth with relatively low roughness, which bodes the optical quality of the films obtained. The optical study shows that the values of the refractive indices derived using the sem-infinite, Fourouhi-Bloomer and EMA models are in good agreement with those of the literature. The study of the optical gap obtained by spectroscopic ellipsometry and the UV-visible spectroscopy reveals some variation depending on various parameters. The waveguiding measurements show that TiO2 films deposited directly on the glass behave as single-mode waveguides in the two polarizations (TM and TE). When SnO2 and ZnO films are used as buffer layers, we note the disappearance of TM modes. The dielectric study shows that the approach based on the Kramers-Kronig analysis and Maxwell's equations is proved acceptable in comparison with other known models. The analysis of wetting water shows the super-hydrophilicity of TiO2/verre and TiO2/(ZnO/glass) samples. Thu, 08 May 2014 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14840 2014-05-08T00:00:00Z http://depot.umc.edu.dz/handle/123456789/14805 Etude et caractérisation des spinelles CuAl2O4 et MgAl2O4 synthétisés par différentes techniques. Moulla, Fatima; Boukheit, Nahemen The work of this thesis is part of recent research concerning the development and characterization of nanometric oxides by different techniques. In view of the comparison with the many works already carried out of this important and still current subject, we were interested in the synthesis and the characterization of the two spinels CuAl2O4 and MgAl2O4 despite the complexity of the mechanisms involved in the Sol-Gel process. The first part was devoted to the structural characterization of CuAl2O4 and MgAl2O4 spinels but also to that of the mixed oxide CuAlO2. The characteristics of each of these bodies are explained according to the different synthesis conditions and the experimental means available. This work clearly establishes the nanoscale size of the three bodies. On the other hand, the presence of intermediate reaction phases has been demonstrated in the two spinels CuAl2O4, MgAl2O4. In the second part, we aimed to high light the role of pressure on pellets prepared from CuAl2O4 and MgAl2O4 powders calcined at 900°C for 4 hours. Following fine characterization techniques, this work has made it possible to observe structural modifications in the case of CuAl2O4 pellets. In the last part, we give a more technological application of the two spinels by studying the degradation of methylene blue by the two spinels. Sun, 18 Jun 2023 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14805 2023-06-18T00:00:00Z http://depot.umc.edu.dz/handle/123456789/14746 Supersymétrie en mécanique quantique relativiste et non relativiste et applications à des problèmes avec masse dépendante de la position par l’approche supersymétrique. Medjenah, Samia; Benamira, Farid This work concerns the application of the approach of supersymmetry in quantum mechanics (SUSYQM) to solve the one-dimensional Schrödinger, Klein-Gordon and Dirac equations for a particle of position-dependent mass subject to known potentials. Within the framework of the Schrödinger equation, we present the resolution of a model with a mass distribution that we can qualify as a Hulthén-type function and subject to a one-dimensional Morse-type potential. We solved it exactly by the generalized SUSYQM approach and obtained the spectrum of bound states and the corresponding eigenfunctions in an elegant algebraic way. In the second work, we solved an interesting model of Klein-Gordon equation with constant mass and mixing proportional scalar and vector potentials. The resolution was made using the approach of standard SUSYQM. But since the Klein-Gordon equation is not an eigenvalues equation and the effective potential explicitly depends on the energy, we used an interesting anzatz to successfully use standard SUSYQM unambiguously. Then, the energy levels are obtained in compact form with constraints on the problem parameters that must be satisfied for the physical solutions. Concerning the Dirac equation, we considered a particle whose mass depends on the position and placed in a vector potential. For a vector potential equal or opposite to the mass term, we reduced the upper component equation of the two-dimensional spinor to a position-dependent mass Schrödinger-type equation with an energy-dependent effective potential. By choosing the potential as a hyperbolic function and using generalized SUSYQM, combining with the previous ansatz, the spectrum and the eigenfunctions are explicitly obtained in a compact form. Wed, 21 Jun 2023 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14746 2023-06-21T00:00:00Z http://depot.umc.edu.dz/handle/123456789/14739 Approche numérique de la convection naturelle dans des espaces annulaires excentrés remplis de nanofluides hybrides. Allouche, Bilel; Djezzar, Mahfoud; Taybi, Tahar In this work, we have numerically analyzed the problem of heat transfer by laminar and permanent natural convection in an eccentric annular space filled with a hybrid nanofluid. The two internal and external cylindrical walls are maintained respectively at the temperature Th and Tc. The fluid is considered Newtonian and the flow is incompressible. The governing equations formulated in bipolar coordinates are written in terms of dimensionless equations. The resulting algebraic equations are discretized by the finite volume method and solved by a FORTRAN language. Numerical simulation is performed for Rayleigh numbers: Ra=103, 104, 105, different radiation numbers: Nr=0, 0.5, 1, 10, 25, 50, different volume fractions: 0-4 % and the geometry parameters (the angle of inclination α= 90°, the radius ratio r = 2.4 and the relative eccentricity e = 0.6. The results obtained show that increasing the volume fraction improves the transfer rate of heat for the considered values of the Rayleigh number. They also show that the average Nusselt number increases considerably with the increase in the radiation number and that the stability of the flow is improved by the presence of the radiation. Mon, 19 Jun 2023 00:00:00 GMT http://depot.umc.edu.dz/handle/123456789/14739 2023-06-19T00:00:00Z