http://depot.umc.edu.dz/handle/123456789/13107 2026-05-01T04:46:54Z http://depot.umc.edu.dz/handle/123456789/13881 Structural and optical properties of CuO:PVC nanocomposite films Troudi, B.; Halimi, O.; Djebli, A. Metal oxides constitut the most diverse class of materials having properties covering almost all aspects of materials science and of physics. Among these materials, copper oxide CuO is very promising. It is a p-type semiconductor material with a band gap of about 1.8 eV. The growing interest granted to CuO is due to many potential applications that it offers in the conversion of solar energy, optoelectronics and photocatalytic degradation of organic pollutants. It is also used in consumer products such as pillowcases and socks because of its cosmetic and antimicrobial properties. In this work, we studied the structural and optical properties of hybrid nanocomposite consisting of Polyvinyl chloride (PVC) as a matrix and the crystallites of the semiconductor CuO as a filler. The samples in the form of thin films are deposited on glass substrates by the dip-coating technique using a colloidal solution prepared by dissolving the Polyvinyl chloride and dispersing the CuO nanocrystallites. The CuO nanoparticles have been previously synthesized by the hydrothermal method. The characterization of the films of the CuO:PVC nanocomposite by the X-ray diffraction (XRD ) has shown the incorporation of the CuO crystallites with monoclinic phase in the amorphous matrix or PVC. The resolution and intensity of the diffraction peaks show a good crystallinity and a random orientation of the crystallites of CuO.The CuO crystallite size was determined using the Scherrer relation ship and it was estimated to about 20 nm. Analysis of the CuO:PVC nanocomposite by the spectroscopy Raman and infrared confirmed the presence of the CuO cristallites in the PVC matrix by revealing vibration modes which are specific to the Cu-O bond. Surface morphology and topography of the CuO:PVC nanocomposite thin films were highlighted with the help of atomic force microscopy (AFM) and from which we deduce the homogenous dispersion of CuO crystallites. The characterization by the measurement of the optical absorption in the UV-Visible domain allows to observe a band at 372 nm which is attributed to the CuO nanocrystallites because the PVC is optically transparent in the UV-Visible domain. The optical gap of the CuO:PVC nanocomposite was estimated to 3.46 eV. Some discrepancies with respect to the gap of PVC and of bulk CuO are due to the nanometric size of the CuO crystallites and to the effect of the interaction between the CuO crtstallites and the PVC matrix. This variation of the gap is a result of the new optical behavior of PVC when it is doped with CuO nanocrystallites. Photoluminescence (PL) spectrum has showed two emissions bands in the visible domain at 500 nm (green emission) and 695 nm (red emission). 2016-12-15T00:00:00Z http://depot.umc.edu.dz/handle/123456789/13863 Characterization of PbS nanoparticles trapped in Y zeolite by X ray diffraction and scanning electron microscopy Tebani, H.; Keghouche, N. The present study examines the PbS semiconductor nanoparticles trapped in Y zeolite synthesized at room temperature via a simple chemical reaction when 2-mercaptoethanol noted RSH was used with a different amounts as a sulfur source. The obtained samples were calcined at various temperatures (T = 100 - 550°C). X ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize the samples at different steps of their elaboration. After thiol addition, the X-rays diffraction reveals the formation of galena lead sulfide phase. The PbS crystallite size, is about 20 nm. After calcinations XRD patterns present the features of PbS. These results are in good agreement with SEM observations which show rod-shapped crystallites corresponding to the first series of samples (ɸ = 20-50 nm, l = 5-10 μm). In the second series the crystallites form clusters at 550°C with an average size of 20-50 nm. 2016-12-14T00:00:00Z http://depot.umc.edu.dz/handle/123456789/13860 Study of structural and optical properties of Fe doped ZnO thin films prepared by spray pyrolysis technique. Serrar, A.; Bouzid, K.; Roustila, A. ZnO and Fe-doped ZnO thin films have been prepared by spray pyrolysis on glass substrates and the influence of Fe-doping concentration on the structural and optical properties of the films has been studied. The experiment results show that all samples synthesized by this method possess hexagonal wurtzite crystal structure with good crystallization, no other impurity phases are observed.The X-ray diffraction (XRD) analysis shows that Fe doping has a significant effect on crystalline quality, grain size and Lattice parameters of thin films. With increasing Fe doping percentage, the crystal quality deteriorated. Moreover, UV spectroscopy demonstrates the influence of Fe-incorporation on visible range transmittance of ZnO where the best transmittance is obtained for 2 at% doping, and in my actual work I study the texture for the precedent samples with the pole figure. 2016-12-15T00:00:00Z http://depot.umc.edu.dz/handle/123456789/13859 Elaboration et propriétés structurales des nanoparticules bimétalliques Ni-Ce et Ni-Pt supportées sur α-Al2O3 Seridi, F.; Chettibi, S.; Keghouche, N. L’objectif de cette étude est la préparation et la caractérisation de nanoparticules bimétalliques Ni-Ce et Ni-Pt supportés sur α-Al2O3. Ces matériaux sont testés comme catalyseurs dans la réaction d’hydrogénation du benzène. Les nanoalliages Ni-Ce et Ni-Pt supportés sur α-Al2O3 sont synthétisés en utilisant la méthode de co-imprégnation des précurseurs métalliques par le support. Ils sont ensuite réduits, chacun selon deux voies: soit par traitement thermique sous H2, soit par radiolyse sous rayonnement gamma. Pour les échantillons Ni-Ce/Al2O3, l'étude structurale par diffraction des rayons X et microscopie électronique en transmission a permis de mettre en évidence la formation de la phase CeO2 de taille nanométrique (8 nm) dans le cas où le procédé de réduction est le traitement thermique sous H2. Dans le second protocole de réduction sous rayonnement ionisant γ, la DRX a révèle la présence des phases Ni et Ce2Ni7. Une forte dispersion de nickel résulte également de la formation de NiO, observée uniquement par MET. Les échantillons Ni-Pt/Al2O3 radiolytiques montrent la présence des nanoparticules monométalliques Ni, Pt et des nanoparticules bimétalliques NiPt et Ni3Pt, de taille de l’ordre de 3,5 nm. Les échantillons réduits sous rayonnement sont testés dans l’hydrogénation du benzène. Ils présentent tout les deux des taux de conversion élevés. Cependant, Ni-Pt/ Al2O3 est plus efficace que Ni-Ce/Al2O3. 2016-12-14T00:00:00Z