Publications Scientifiques
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Item Effect of TiN thin films deposited by oblique angle sputter deposition on sol-gel coated TiO2 layers for photocatalytic applications(Elsevier, 2024) Naas, Lazhari-Ayoub; Bouaouina, Boudjemaa; Bensouici, Fayçal; Mokeddem, Kamel; Abaidia, Seddik-El-HakTiO2 monolayer and TiN/TiO2 bilayer coatings were deposited on soda-lime glass prepared by mixing two techniques, TiO2 was deposited by sol-gel dip-coating and TiN film was deposited by oblique angle deposition using reactive magnetron sputtering at α=45° Structural analysis showed typical peaks of TiO2 anatase phase and cubic (Na-Cl type) structure of TiN. Roughness value of 3 nm was obtained for the TiN/TiO2 bilayer film with a rise and elongated grains size. It was found that the optical band gap energy decreases after coupling the TiN sub-layer which is explained by the incorporation of N atoms into TiO2 structure. At constant UV irradiation time, the photo-degradation of methylene blue rate increased for TiN/TiO2 film by 4 % compared to TiO2 filmItem Oxygen diffusion and migration in clean and defective uranium nitride UN (0 0 1) surfaces(Elsevier, 2018) Zergoug, T.; Abaidia, Seddik-El-Hak; Nedjar, A.This study focuses on the diffusion of atomic and molecular oxygen through the uranium mono-nitride UN (0 0 1) surface. The adsorption of oxygen at the most favorable sites has been checked on different surface states namely: clean surface and surfaces containing defects such as inclusion atoms. Inclusions atoms are positioned at a uranium U atom vacancy or at a nitrogen N atom vacancy location of the UN (0 0 1) surface. Neptunium, plutonium, protactinium, silver and neodymium which are the most probable nuclear reactions (n, U) products have been selected as U atom substitute. Some light elements such as carbon, chromium and silicon were used to replace an N atom. The first principle calculation, based on Density Functional Theory (DFT) was used, taking into account the Generalized Gradient Approximation (GGA) and the Projector-Augmented Wave (PAW) to describe the exchange-correlation functional. The purpose of this work is to verify the oxygen adsorption energy variations performed across all the studied surfaces. The most favorable sites of UN (0 0 1) clean and defective surfaces to oxygen O atom diffusion were preliminary identified. In the second step, atomic dynamical Potential Energy Surface (PES) was used to study the interaction between O atom and UN (0 0 1) surfaces at these sites. Finally, Nudged Elastic Band (NEB) method was used in order to investigate the migration of O atom through the UN (0 0 1) surfaces. The results show that at the bridge site, the adsorption and incorporation energies of oxygen atom on and in the UN (0 0 1) surfaces respectively, do not substantially vary with the type and position of the studied impurities. But, at the N vacancy site, the adsorption energy of the O atom decreases practically when UN (0 0 1) surfaces contain inclusion atoms compared to the clean surface case. Furthermore, the NEB calculations show discrepancies for the Minimum Energy Path (MEP) during the migration of the O atom at the bridge site through the studied UN (0 0 1) surfaces and depending on the type and position of the added impurities. Among the studied MEPs, protactinium is found to be the most suitable barrier to the diffusion of oxygen through the UN surface as an inclusion on UN (0 0 1)Item Silicon nanowire-hydrogenated TiO2 core-shell arrays for stable electrochemical micro-capacitors(Elsevier, 2021) Bencheikh, Yasmina; Addad, Ahmed; Coffinier, Yannick; Kumar, Umesh; Roussel, Pascal; Szunerits, Sabine; Hadjersi, Toufik; Amin, Mohammed A.; Abaidia, Seddik-El-Hak; Boukherroub, RabahIn this paper, we fabricated silicon nanowire-TiO2 core-shell arrays in a two-step process. First, silicon nanowire arrays (SiNW) were prepared in HF/AgNO3 aqueous solution using metal-assisted chemical etching of bulk silicon. Then, atomic layer deposition (ALD) technique was applied to coat a 20 nm thin shell TiO2 film. The TiO2/SiNW substrates were afterward annealed at 400°C in hydrogen atmosphere for 4 h and tested as electrode materials for electrochemical micro-capacitors. The electrochemical features of the constructed H−TiO2/SiNW electrode were assessed in an aqueous 1 M Na2SO4 electrolyte solution and revealed that the specific capacitance increased six times compared to non-annealed TiO2/SiNW and 20-fold compared to a reference SiNW electrode under the same operating conditions. Importantly, H−TiO2/SiNW also displayed a high stability over 30,000 cycles at 0.1 mA cm−2 with an overall decrease of 19% of the initial capacitance. The hydrogen treatment increased the density of hydroxyl group and enhanced the carrier density on TiO2 surface improving the capacitive properties of H−TiO2/SiNWItem An estimate of a frequency characterizing the electrochemical stability of a gold electrode modified by MHDA thiol in different ways(Croatian Chemical Society, 2021) Chaibi, Sarah; Zabat, Mokhtar; Hadjersi, Toufik; Abaidia, Seddik-El-Hak; Zine, Nadia; Yaakoubi, Nourdin; Errachid, AbelhamidA theoretical investigation aimed at estimating a characteristic frequency in the medium-low frequency domain in which the impedance response of a given interface measured by electrochemical impedance spectroscopy (EIS) is almost constant, constitutes the basic idea of this work. A theoretical model was subsequently applied to the data resulting from EIS measurements performed on gold electrodes modified by various ways of 16-mercaptohexadecanoic acid (MHDA) thiol functionalization. Analysis of these data revealed a direct relationship between the way the substrate was modified and this characteristic frequencyItem Effect of Ar/N2 flow ratio on the microstructure and mechanical properties of Ti-Cr-N coatings deposited by DC magnetron sputtering on AISI D2 tool steels(Elsevier, 2021) Kehal, Abdelkrim; Saoula, Nadia; Abaidia, Seddik-El-Hak; Nouveau, CorinneTi-Cr-N coatings were deposited on Si (100) and AISI D2 tool steel substrates by reactive DC magnetron co-sputtering technique from titanium and chromium target in mixed Ar/N2 atmosphere. The Ar/N2 ratio effects on the chemical composition, structure, morphology, intrinsic stress and mechanical properties of the Ti-Cr-N coatings were investigated. The growing process of Ti-Cr-N coatings can be divided into three stages: Stage I, in poisoning mode (low flow ratio 1 < Ar/N2 ≤ 1.4), Stage II, in transition mode (intermediate flow ratio 1.4 ≤ Ar/N2 ≤ 3) and Stage III in metallic mode (Ar/N2 > 3). For all samples, XRD analysis shown the formation of mixed nitrides phases. In stage I, Ti2N, TiN0.3, and hexagonal-Cr2N phases were observed. In Stage II, TiN0.3, Cr2N, and cubic-TiN phases were formed, while only TiN and Cr2N are observed in stage III. The coatings deposited with Ar/N₂ ratio of 3 shows the largest hardness of 24 GPa which is attribute to the dense structure and smoother surface morphology. The properties of the films are discussed in terms of evolution growth stages resulting by the variation of Ar/N2 flow ratiosItem High performance silicon nanowires/ruthenium nanoparticles micro-supercapacitors(Elsevier, 2019) Bencheikh, Yasmina; Harnois, Maxime; Jijie, Roxana; Addad, Ahmed; Roussel, Pascal; Szunerits, Sabine; Hadjersi, Toufik; Abaidia, Seddik-El-Hak; Boukherroub, RabahThe continuous increase of small electronic devices calls for small energy storage components, commonly known as micro-supercapacitors, that can ensure autonomous operation of these devices. In this work, we propose a simple and straightforward method to achieve high energy and power densities of a silicon-based micro-supercapacitor, consisting of silicon nanowires decorated with ruthenium nanoparticles (Ru/Si NWs). The Si NWs are obtained through the common vapor-liquid-solid (VLS) growth mechanism, while a simple electroless process is used to deposit Ru nanoparticles. While silicon nanostructuration allows to increase the surface area, coating with Ru NPs introduces a pseudocapacitance necessary to attain high energy and power densities. The Ru/Si NWs micro-supercapacitor exhibits a specific capacitance of 36.25 mF cm−2 at a current density of 1 mA cm−2 in a neutral Na2SO4 electrolyte and a high stability over 25 000 cycles under galvanostatic charge-discharge at 1 mA cm−2. A solid state supercapacitor is then fabricated with symmetric electrodes separated by a polyvinyl alcohol/sulfuric acid electrolyte. The device displays a specific capacitance of ∼18 mF cm−2 at a current density of 1 mA cm−2 and a specific power density 0.5 mW cm−2. This solid-state nanowire device also exhibits a good stability over 10 000 galvanostatic charge-discharge cyclesItem Residual stress, mechanical and microstructure properties of multilayer Mo 2 N/CrN coating produced by R.F Magnetron discharge(Elsevier B.V., 2017) Bouaouina, Boudjemaa; Besnard, A.; Abaidia, Seddik-El-Hak; Haid, F.We have investigated the effect of the period thickness of the multilayer Mo 2 N/CrN deposited on Si substrate produced by reactive magnetron sputtering. Mo 2 N presents a face centered cubic structure and CrN an orthorhombic one. The residual stress of the coatings was determined by the measurement of the substrate curvature. The microstructure of the multilayer was investigated from the X-ray diffraction and scanning electron microscopy (cross section images). The residual stresses resulting from the deposition of the different bi-layer thickness were measured and correlated to the structural properties of the coating as well as the nanoindentation analysis of the coating. The stresses are compressive and tensile for the individual Mo 2 N and CrN layer respectively. The result shows that an increase of the multilayer coatings Mo 2 N/CrN thicknesses induce an increase of the hardness and the elastic modulus, in the other hand the tensile stress increases. The shift of the XRD diffraction peak (1 1 1) of Mo 2 N at high angle which means the reduction of the residual stress is in good agreement with the residual stresses measurementsItem Microstructure, corrosion and magnetic behavior of an aged Dual-Phase stainless steel(Springer, 2018) Ziouche, Aicha; Haddad, A.; Badji, Riad; M. Zergoug, M. Zergoug; Zoubiri, N.; Bedjaoui, W.; Abaidia, Seddik-El-HakItem Cooling enhancement of planar-balanced magnetron cathode(Springer, 2017) Salhi, M’hamed; Abaidia, Seddik-El-Hak; Mohamedi, Brahim; Laouar, SofianeItem Pulsed eddy current signal analysis of ferrous and non-ferrous metals under thermal and corrosion solicitations(Springer, 2017) Ziouche, A.; Zergoug, M.; Boucherrou, N.; Boudjellal, H.; Mokhtari, M.; Abaidia, Seddik-El-Hak