http://depot.umc.edu.dz/handle/123456789/12815 2026-05-31T17:07:38Z http://depot.umc.edu.dz/handle/123456789/12818 Behaviour of dislocations near phase boundaries inbicrystals of FCC materials: Au-X, X = Pb, Cu and Ni Ouchtati, A; Khalfallah, O The mechanical properties of materials are determined by the interactions between defects found in the crystal. In a bicrystal of bimaterials, the result forces exercising on the matrix dislocation near and parallel to an interface comprehend a term due to the interface presence and qualified by "image force " . The image force effects on dislocations near and parallel to an interphase boundaries are examined as a function of the interphase boundary disorientation in bicrystals of FCC materials Au-X with X : Pb, Cu and Ni. The elastic interaction energy ΔE is calculated on the basis of the anisotropic linear elasticity theory between dislocations located in the crystal (1), Au, having a Burgers vector = a/2 [110] and interphase boundaries that are characterized by their rotation axis R=[110] and disorientation angle ranging between 0° and 90°. A good correlation is found between the sign and the magnitude order of the interaction energy ΔE and the sign and magnitude order of the shear moduli difference ,Δμ=μ2-μ1, of the two materials constituent the bicrystal. The image force can be repulsive or attractive according to the sign and the intensity of shear moduli difference. The isoenergy maps have various symmetries according to the disorientation value 2016-12-15T00:00:00Z http://depot.umc.edu.dz/handle/123456789/12817 BaTiO3-TiO2 nanotubesproduced by classical hydrothermal methodand their photoelectrochemical properties Sobti, N; Kendouli, S; Baghriche, M; Achour, S Nanotubes are of great interest due to their high surface-to-volume ratios and size-dependent properties. Titanium dioxide nanotube array is a well-known nanostructured semiconductor oxide with improved functional photocatalytic and sensing properties. Considering these properties, TiO2 NTs arrays attract wide scientific interest in view of their applications in self-cleaned gas sensors, photo catalytic materials, dye sensitized solar cells, and water photo electrolysis. In this work, TiO2 nanotubes were prepared by anodization of pure titanium sheets and subsequently covered with BaTiO3 using classical hydrothermal method(200 °C during 2 hours). TheTiO2 nanotubes were prepared using 2wt. %NH4F in ethylene glycol and water under constant voltage 40 V for 4 hours. Thereafter, the prepared samples were hydrothermally processed in a solution of 0.004, 0.006,0.008M Ba(HO)2respectively, and preheated distilled water in classical oven. Different techniques of analysis such as X-ray Diffraction (XRD), Raman Spectroscopyand Scanning Electron Microscopy (SEM) were used to characterize the obtained layers. The formation of BaTiO3 was confirmed by Raman analysis. SEM image of these layers showed the coverage of TiO2 nanotubes by BaTiO3nano-particles 2016-12-15T00:00:00Z http://depot.umc.edu.dz/handle/123456789/12816 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