29 Works

Lead-free BNT piezoelectric thin films by sol-gel method

S. Abou Dargham, F. Ponchel, M. Soueidan, A. Khoury, J. Assaad, D. Remiens & D. Zaouk
The objective of this work is to synthesize lead-free piezoelectric thin films by the Sol-Gel method: bismuth sodium titanate (Bi0.5Na0.5TiO3 or BNT). BNT films were annealed with the rapid thermal process (RTP). The film treated at 700°C is dense and well crystallized in the perovskite phase. The first results of electrical characterizations showed promising dielectric, ferroelectric and piezoelectric performance. At 12 kHz, the dielectric constant and losses are 430 and 0.07, respectively. Ferroelectric hysteresis measurements...

The Ninth International Seminar on Ferroelastic Physics. Abstracts Book

L.N. Korotkov, S.A. Gridnev & A.S. Sidorkin
The 9th International Seminar on Ferroelastics Physics has been organized in Voronezh in september, 2018. This article is the conference volume, it contains the abstracts of about 90 contributions presented at ISFP9, dedicated to the following aspects of ferroelastic physics: Phase Transitions; Lattice Dynamics and Soft Modes; - Crystal Growth, Structure and Physical Properties; Heterogeneous; Glassy and Incommensurate Systems; Domains, Domain Boundaries and Their Dynamics; Multiferroics and Miscellaneous.

Simulation and optimization of the nSiC layer’s thickness in a nSiC/Si photovoltaic cell

M. Kabe, Y. Lare, L. Ottaviani, M. Pasquinelli, D. Barakel & M. Portail
Simulations of the emitter layer in 3C-SiC heterostructure solar cells were performed by means of the SCAPS software to model the optimal thickness and predict the influence on cell’s behaviour. Then, the cells have been elaborated by chemical vapor deposition and characterized. The opto-electrical measurements showed an improvement of the absorption of photons in the short wavelengths thanks to the thin layer of the emitter, and the non-degradation in bulk of the base cell. On...

ARMA model for short-term forecasting of solar potential: application to a horizontal surface on Dakar site

A. Mbaye, M.L. Ndiaye, D.M. Ndione, M. Sylla, M.C. Aidara, M. Diaw, V. Traoré, A. Ndiaye & P.A.S. Ndiaye
This paper presents a model for short-term forecasting of solar potential on a horizontal surface. This study is carried out in to the context of valuing of energy production from photovoltaic solar sources in the Sahelian zone. In this study, Autoregressive Moving Average (ARMA) process is applied to predict global solar potential on a 24 hours time horizon. The ARMA (p, q) is based on finding optimum parameters p and q to better fit considered...

ARMA model for short-term forecasting of solar potential: application to a horizontal surface on Dakar site

A. Mbaye, M.L. Ndiaye, D.M. Ndione, M. Sylla, M.C. Aidara, M. Diaw, V. Traoré, A. Ndiaye & P.A.S. Ndiaye
This paper presents a model for short-term forecasting of solar potential on a horizontal surface. This study is carried out in to the context of valuing of energy production from photovoltaic solar sources in the Sahelian zone. In this study, Autoregressive Moving Average (ARMA) process is applied to predict global solar potential on a 24 hours time horizon. The ARMA (p, q) is based on finding optimum parameters p and q to better fit considered...

A simple and inexpensive technique for obtaining low dimensional semiconductor nanostructures

S. Larramendi
The isothermal closed space sublimation (ICSS) is a simple and effective technique of low- cost, used to obtain thin films of semiconducting materials, embedding nanoporous substrates with semiconducting materials, or to grow nanocrystals inside pores. In this work it is explained how to use this technique to conform semiconductor structures using porous alumina membranes and ZnO nanorod matrix as template. As a result a structure with potential use in photovoltaic solar cells is obtained, with...

Modelling and simulation of an automatic solar module characteristics data acquisition system

E. Akoro, G.J.P. Tevi, M.E. Faye, M. Sene & A.S. Maiga
This paper is devoted to the design and simulation of an automatic data acquisition system of solar module characteristics. The system is essentially composed of three parts. The first part is devoted to the acquisition of the electrical parameters of the solar module (Current, Voltage and Power) in automatic ways using an automatic variable load. The second part is focused on devices which measure the ambient temperature and solar irradiation. In the last part, we...

Characterization and modeling of solar radiation on the ground, application to the estimate of solar potential available on the coast of Nouakchott

Ahmed Sidibba, Diene Ndiaye, Sidi Bouhamady & Menny El Bah
The purpose of this work is to evaluate four empirical models developed in literature such as Ghouard, Perrin Brichambaut, Bird and Hulstrom and Dependent model of the Link trouble factor. The validation of these different theoretical models was carried out using solar global radiation data collected on the Cheikh Zayed Nouakchott power plant. These measurements were carried out at a time step of 5 minutes during the period of one year. (April 1, 2015 to...

Optical properties of PZN-PT nanoparticles thin layer on ITO glass for photovoltaic application

R. Ndioukane, D. Kobor, L. Motte & J. Solard
In this work, undoped and Mn doped Pb(Zn 1/3 Nb 2/3 )O 3 -4.5PbTiO 3 nanoparticles were dispersed in biopolymer and in mixed biopolymer + pentacene as active layer and deposited by spin coating on ITO glasses. Morphological, optical and electrical properties of these layers were investigated. SEM images show the superposition of different deposited layers ITO/TiO2/PZN-PT-np-biopolymer on glass substrate with thicknesses of 1.600 μm, 1.505 μm and 1.765 μm respectively. The absorbance value in...

Design and optimization of silicon nanostructures

B. Dieng, M. Beye, M. Toure, D. Diouf, D. Kobor & A.S. Maiga
in this work, recent advances in various silicon nanostructures used in crystalline silicon solar cells for antireflection and light trapping are reviewed. Simulations and optimizations are also performed for the most relevant of these nanostructures. The results showed that nanocones and nanoparaboloids outperform nanopillars and give almost the same antireflective performance, reducing the average reflectance of the crystalline silicon surface below 2% in the wavelength range 300-1100 nm and under normal incidence. This reflectance is...

Raman active modes of single-wall boron nitride nanotubes inside carbon nanotubes

A.M. Nassir, AH. Rahmani, M. Boutahir, B. Fakrach, H. Chadli & A. Rahmani
The structure of boron–nitride nanotubes (BNNTs) is very similar to that of CNTs, and they exhibit many similar physical and chemical properties. In particular, a single walled boron nitride nanotube (BNNT) and a single walled carbon nanotube (CNT) have been reported. The spectral moment’s method (SMM) was shown to be a powerful tool for determining vibrational spectra (infrared absorption, Raman scattering and inelastic neutron- scattering spectra) of harmonic systems. This method can be applied to...

Lecture on the anomalous diffusion in Condensed Matter Physics

M. Benhamou
Diffusion is a natural or artificial process that governs many phenomena in nature. The most known diffusion is the Brownian or normal motion, where the mean-square-displacement of the tracer (diffusive particle among others) increases as the square-root of time. It is not the case, however, for complex systems, where the diffusion is rather slow, because at small-scales, these media present an heterogenous structure. This kind of slow motion is called subdiffusion, where the associated mean-square-displacement...

Identification of mono- and few-layer graphene: Raman study

M. Boutahir, Ah Rahmani, H. Chadli & A. Rahmani
In this theoretical work, the Raman spectra were analyzed by considering the origin of the G peak, its shape, position and relative intensity as a function of the number of graphene layers. By using the spectral moment’s method, the Raman spectra of mono, bi and few-layers of graphene are calculated and a good agreement was found with group theory concerning the number of the Raman-active modes and the Raman measurements. Our results provide a Raman...

ZnTe/CdSe type-II core/shell spherical quantum dot under an external electric field

A. Chafai, I. Essaoudi, A. Ainane, F. Dujardin & R. Ahuja
We have investigated in the framework of the envelope function approximation and taking into account the dependence of the electron effective mass on radius the energy of an electron inside a ZnTe/CdSe core/shell spherical quantum dot. In order to make the problem more realistic, we describe the conduction band- edge alignment between core and shell materials by a finite height barrier. By applying the Ritz variational principle the effect of the electric field on the...

Carbon nanotubes functionalized with copper hexacyanoferrate nanoparticles for a selective extraction of cesium from liquid waste

H. Draouil, L. Alvarez, J. Causse, V. Flaud, M.A. Zaibi, J.L. Bantignies, M. Oueslati & J. Cambedouzou
Single-walled carbon nanotubes are functionalized with copper hexacyanoferrate nanoparticles for the liquid-solid extraction of cesium from liquid waste and contaminated water. The functionalization process is followed mainly by x-ray photoemission spectroscopy. Indeed, determining the chemical environment around carbon or nitrogen atoms allows to evidence the formation of covalent bounding. In addition, the signatures of iron and copper ions give information on the effective growth of hexacyanoferrate nanoparticles. Furthermore, the cesium sorption mechanism is investigated by...

Investigation of DNA denaturation from generalized Morse potential

R. El Kinani, H. Kaidi & M. Benhamou
In this paper, we present a non-linear model for the study of DNA denaturation transition. To this end, we assume that the double-strands DNA interact via a realistic generalized Morse potential that reproduces well the features of the real interaction. Using the Transfer Matrix Method, based on the resolution of a Schrödinger equation, we first determine exactly their solution, which are found to be bound states. Second, from an exact expression of the ground state,...

Vortex phase transition and superconducting properties of organic quasi-two-dimensional k-(BEDT-TTF)2Cu[N(CN)2]Br

H. El Ouaddi, A. Tirbiyine, A. Taoufik, Y. Ait Ahmed, F. Chibane, H. Chaib, A. Nafidi & S. Snoussi
We report investigations of the low temperature dc susceptibility and the magnetization on the layered organic superconductor κ-(BEDT-TTF)2Cu[N(CN)2]Br near 80K and the effect of disorder on the superconducting transition temperature Tc. The shielding effect (S) and the critical current density Jc were studied (with H parallel to the c axis of the crystal). Jc can be estimated by analysis of magnetic hysteresis measurement using the Bean model. For each temperature value, we observed two regimes...

Extensive study of cage effect and subdiffusion in Pickering emulsions using molecular dynamics simulations

S. El Moudny, M. Benhamou, M. Badia & M. Ossmani
In this work, we aim at an extensive study of the diffusion phenomenon of oil-droplets dispersed in water onto which are strongly adsorbed charged point-like particles (Pickering emulsions). This diffusion that originates from multiple collisions with the molecules of water, is anomalous, due to the presence of relatively strong correlations between the moving oil-droplets. Using Molecular Dynamic simulation, with a pair-potential of Sogami-Ise type, we first observe that the random walkers execute a normal diffusion,...

Raman-active modes in defective peapod

F. Fergani, S.M. Ait Abdelkader, H. Chadli, A.H. Rahmani & A. Rahmani
The vibrational properties of defective single-walled carbon nanotube filled with C60 fullerene is the subject of the current study. For this aim we use the spectral moments method in the framework of the bond-polarization theory to calculate the nonresonant Raman spectra of hexa-vacancy defective C60 peapods. Essentially, the vibrational properties are closely coupled with the atomic structure of the system. The evolution of the Raman spectrum as a function of the spatial arrangement of defects...

Polymer nanocomposites from natural clay: Understanding clay-PEG interaction and their effect on spacing between clay-plates

S. Ghyati, M. Benhamou, M. El Jai & I. Akhrif
The interactions between clay-plates and hydrophilic polymer are investigated assuming that the polyethylene glycol chains are grafted onto face-to-face clay-plates. Besides the usual van der Waals attractive interaction, the clay-plates experience a repulsive effective interaction, due to the excluded volume force between monomers along the grafted PEG chains. The face-to-face clay- plates then play the role of polymer brushes. The free energy (per unit area) of a clay-plate pair is the sum of these interactions,...

First principles calculations of electronic and optical properties for mixed perovskites: Ba(1-x)Ca(x)TiO3 and Ba(1-x)Sr(x)TiO3 (x=0.4, 0.6)

O. Tahiri, S. Kassou, R. El Mrabet & A. Belaaraj
The effect of Ca and Sr-doping on the structural electronic and optical properties of the cubic Ba(1- x)CaxTiO3 and Ba(1-x)SrxTiO3 (x=0.4, 0.6) mixed crystals was investigated using first-principles calculations based on density functional theory (DFT). The calculated band structures based on the optimized geometry of the cell for the solid solutions show an indirect band gap character at M-points, with low energy dispersion along height symmetry directions in the Brillouin zone. The band gaps increase...

ISPDS2 - Second International Symposium on Physics of Data Storage - Conference volume- Materials and Devices, Vol.2(3), 2017

J.L. Bantignies, L. Alvarez, P. Saint-Gregoire, M. Fouaidy, M. Benhamou, L. Khouchaf, A. Rahmani, Y. Gagou, A. Chahboun, A. Benyoussef, M. Boutahir, B.B. Balogun, J.C.R.E. Oliveira, C.T. Sousa, J.P. Araujo, A.H. Rahmani, H. Chadli, A. Neqali, H.El. Kaddoussi, A. Lahmar, M. Amjoud, A. Alimoussa, E. Choukri, H. Khimakhim, M. El Marssi … & I. Bouziani
The symposium ISPDS2 has taken place in Meknes (Morocco) in October, 2017. It has gathered specialists of various fields who presented their work in connection with the problematics of data storage. This conference volume contains 75 abstracts of communications presented at the meeting as invited conferences, talks, or posters. Various topics are covered.

TEAM1 - First Transpyrenean Encounter on Advanced Materials - Conference volume- Materials and Devices, Vol.2(2), 2017

E. Snoeck, C. Gatel, L.A. Rodriguez, A. Masseboeuf, E. Senokos, V. Reguero, L. Cabana, J. Palma, R. Marcilla, J.J. Vilatela, Ph. Tailhades, I. Pasquet, H. Le Trong, V. Baco-Carles, L. Presmanes, C. Bonningue, M. Gougeon, K. Kiryukhina, V. Conedera, P.F. Calmon, D. Dragomirescu, H. Camon, M.H. Pereira, J.S. Amaral, N.J.O. Silva … & M.S. Mane
The Transpyrenean Encounter on Advanced Materials aims at establishing or reinforcing contacts and collaborations between groups of France, Spain, and Portugal, in the fields of advanced materials, and related topics. The present volume gathers the abstracts of communications given at the occasion of TEAM1 (july 2017), on various topics in different fields of advanced materials.

Encapsulation of a bioactive steroid in a polymer matrix (micro-encapsulation of DI-31 in chitosan by spray drying for various purposes)

A.K. Collado, G. Hernandez, V. Morejon, F. Coll & C. Peniche
DI-31 is a synthetic analog of brasinosteroids (ABR), the active ingredient (PA) of Biobras, a plant growth stimulant, which has shown positive impact on Cuban agriculture, especially in rice cultivation. However, it has the drawback of having low solubility in water and being rapidly metabolized by the plants. An alternative to overcome these limitations is its micro-encapsulation in a polymer matrix. Chitosan (CHI) has been investigated as an excellent candidate for microencapsulation of DI-31. Chitosan...

Modeling of magnetic properties (Cr/NiO/Ni) based multi-layers deposited by magnetron sputtering using Preisach model

A. Bendjerad, A. Benhaya, S. Boukhtache, M. Zergoug & K. Benyahia
In the present work, thin films of Cr/NiO/Ni are deposited on glass substrates using RF magnetron sputtering technique. The uniformity and homogeneity of the prepared films were controlled by varying the power of the source, the target-substrate distance and the pressure of the plasma gas which is argon. In order to test the Preisach Model, we carried out measurements according to two directions: parallel and perpendicular to the substrate plane using a Vibrating Sample Magnetometer...

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