Mohamed EL Hasnaoui | Ibn Tofail (original) (raw)

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Papers by Mohamed EL Hasnaoui

Brazilian journal of physics, Jan 27, 2024

Research Square (Research Square), Feb 15, 2023

Plasmonic nanostructured materials made of nanohole arrays in metal are signi cant plasmonic devi... more Plasmonic nanostructured materials made of nanohole arrays in metal are signi cant plasmonic devices exhibiting resonances and strong electromagnetic con nement in the visible and near-infrared range. As such, they have been proposed for use in many applications such as biosensing and communications. In this work, we introduce the asymmetry in nanoholes, and investigate its in uence on the electromagnetic response by means of broadband experimental characterization and numerical simulations. As a lowcost fabrication process, we use nanosphere lithography, combined with tilted silver evaporation, to obtain a 2D hexagonal array of asymmetric nanoholes in Ag. Our experimental setup is based on a laser, widely tunable in the near-infrared range, with precise polarization control in the input and in the output. We next resolve the circular polarization degree of the transmitted light when the nanohole array is excited with linear polarization. We attribute the disbalance of left and right transmitted light to the asymmetry of the nanohole, which we support by numerical simulations. We believe that the optimization of such simple plasmonic geometry could lead to multifunctional at-optic devices.

Journal of Applied Physics, 2010

7853© 2019 Elsev ion and peer-revie N-2K19. Effect Graphene a D ract Reduced gr ged with Polysty ... more 7853© 2019 Elsev ion and peer-revie N-2K19. Effect Graphene a D ract Reduced gr ged with Polysty rties of Polysty tial property to o fer process that t were plotted in polymer electro uctivity of PL-rG dc conductivity 9 Elsevier Ltd. Al ion and peer-revie N-2K19.

Work presented at the Third Moroccan Spring School on Advanced Materials (moSSAM'3), 12-14 ap... more Work presented at the Third Moroccan Spring School on Advanced Materials (moSSAM'3), 12-14 april 2020, Ouarzazate, Marocco.This study focuses on the development of ternary composites based on polyester matrix reinforced with graphite (Gt) and carbon nanotube (CNT) particles. The structural characterization was performed using small-angle neutron scattering (SANS), infrared (IR), and Raman spectroscopies, providing information about the dispersion of CNT and Gt particles within the matrix. The electrical and dielectric measurements were carried out in a frequency range from 100 Hz to 1 MHz and temperatures from 200 to 400 K. It is observed that, with the addition of CNT, a positive temperature coefficient in resistivity phenomena (PTCR) is identified for the temperatures below the glass transition. The mechanism responsible for this behavior is attributed to the tunneling effect conduction. The dielectric response was analyzed using the complex impedance formalism

Journal of Optoelectronics and Advanced Materials, 2020

Phase formation and structural properties of Ni-doped Li0.976-xNb1.005-x/5NixO3 (0 ≤ x ≤ 0.1) cer... more Phase formation and structural properties of Ni-doped Li0.976-xNb1.005-x/5NixO3 (0 ≤ x ≤ 0.1) ceramics prepared by solid-state reaction method, are investigated in a temperature range from 400 to 900 °C. X-ray diffraction patterns indicate that single phase was formed for lithium niobate ceramics. It was shown that the unit-cell volume of the hexagonal phase decreased with increasing nickel concentration from 0 to 3% Ni charge and increased above 3%. No secondary phases were observed in Ni-doped powder of LiNbO3 for all concentrations compared with that of undoped sample. These results indicate that the Ni 2+ ion was substituted for niobium and lithium ions in the hexagonal phase. The addition of Ni 2+ promotes densification of lithium niobate ceramics. Raman spectra show that the samples were well crystallized with high purity. It was noticed that the increase of Ni-doping causes the decreasing of resistivity at high temperatures, but it has no influence of activation energy.

The electrical properties of a composite, consistin g in a matrix of ethylene butylacrylate (EAB)... more The electrical properties of a composite, consistin g in a matrix of ethylene butylacrylate (EAB) reinf orced with carbon black particles (CB) are studied in the temperature range from 27 to 127 °C. The DC conductivity measurements show an insulator/conductor transition at a volume conce ntration of about Φ*≈11%. The electrical resistivity is constant with temperature, at concentrations below the conduction threshold Φ*. For concentrations above Φ*, the resistivity presents a significant increase for temperatures ab ove the melting point, Tm ≈ 91 °C, which corresponds to the phenomenon known as positive temperature coefficient in resistivity (PTCR effect). Besides, the AC con ductivity of these composites was analysed in the frequency rang e from 40 Hz to 0.1 MHz. The frequency dependence of the AC conductivity is characterized by a low frequency re gion of constant conductivity followed by a gradual transition at higher frequencies to a frequency dependent conduct ivity. This behav...

The dielectric properties of carbon black (CB) loaded in ethylene butylacrylate copolymer composi... more The dielectric properties of carbon black (CB) loaded in ethylene butylacrylate copolymer composite (EBA) were investigated in the frequency range between 10 and 10 Hz and temperature range between 250 and 400 K. The frequency dependence of the dielectric response has been analyzed using the modulus formalism and the electrical conductivity using the Jonscher’s power law. It is found that the activation energy obtained by the modulus method is in good agreement with that obtained by the DC conductivity, which is independent of the CB contents inside the copolymer matrix, suggesting that these particles do not interact significantly with the chain segments of the macromolecules in the EBA copolymer.

The dielectric properties of biocomposite materials based on vinyl resin filled with microcrystal... more The dielectric properties of biocomposite materials based on vinyl resin filled with microcrystalline cellulose, in the frequency range from 100 Hz to 1 MHz and in the temperature range from 280 to 400 K, are presented. Two dielectric relaxations were identified. The first one is attributed to the α-relaxation, associated with the glass transition of biocomposite, and the second one, appearing above the glass transition and at low frequencies, was identified as the interfacial polarization effect, which is attributed to the accumulation of charges at the cellulose microcrystalline/matrix interface. Furthermore, the thermal analysis of their relaxation frequency and the electrical conductivity behaviors showed that the activation energy of these composite is more pronounced for the temperatures above the glass transition temperature, suggesting that the interaction between MCC particles and polymeric matrix became significant with the increase of temperature.

Journal of Composite Materials

Binary and ternary composites were synthesized using a polyester matrix reinforced by two types o... more Binary and ternary composites were synthesized using a polyester matrix reinforced by two types of carbon inclusions, namely, carbon nanotubes (CNT) and graphite (Gt) (CNT/Gt/Polyester). Thermal analyses were performed, using thermogravimetry and differential scanning calorimetry, which allowed us to observe significant changes in glass transition temperatures and degradation temperatures of the composites. Dielectric measurements were performed in a frequency range from 100 Hz to 1 MHz and temperature from –33 to 107°C. The dielectric permittivity values of the CNT/Gt/Polyester ternary composites, compared to the Gt/Polyester binary composites, indicate that the addition of CNT particles to the Gt/Polyester binary system significantly improved the dielectric permittivity, due to the enhanced interfacial polarization of the host matrix, while the frequency dependence of the electrical modulus spectra revealed a Maxwell–Wagner–Sillars dielectric relaxation process that was found to f...

Journal of Electronic Materials

This work presents a study on the electrical and structural properties of percolating composites ... more This work presents a study on the electrical and structural properties of percolating composites based on graphite (Gt) particles dispersed with various concentrations into an insulating polyester matrix (PES). Their structural characterization was performed using small-angle neutron scattering (SANS), providing information about the dispersion of fillers within the matrix. Electrical measurements were carried out in the frequency range from 1 Hz to 10 MHz and temperature from 30°C to 100°C. It was found that when the filler concentration is above the percolation threshold and the temperature above the glass transition, the positive temperature coefficient of resistance is identified. The mechanism responsible for this behavior was attributed to the tunneling effect. The Nyquist representations of the complex impedance spectra were modeled using the Cole–Cole model. The obtained values of the α exponent that gauges the broadening of the loss spectrum suggest a behavior close to a model of a single relaxation time.

Advances in Materials and Processing Technologies

The direct current (DC) conductivity of carbon blac k (CB) filled EAB composite material was meas... more The direct current (DC) conductivity of carbon blac k (CB) filled EAB composite material was measured in the temperature range from 130 to 290 K ( Tg ≈ 198 K). That conductivity data was analyzed and interpreted in order to identify the conduction mec hanisms and to observe the doping effect of CB particles on the EAB matrix. It shows that the cond uction, in the high temperature region ( T > Tg), is due to thermally activated tunneling of charge carriers in the band, and, in the low temperature range ( T < Tg), conduction takes place through variable range ho pping in the localized states near the Fermi level.

2020 International Conference on Intelligent Systems and Computer Vision (ISCV)

Journal of Reinforced Plastics and Composites

In this paper, we report an investigation on electrical conduction mechanisms of nanofluids based... more In this paper, we report an investigation on electrical conduction mechanisms of nanofluids based on commercial engine oil loaded with graphite (Gt) and multiwalled carbon nanotubes, at different concentrations. The impedance spectroscopy technique was used to measure the resistance and capacity characterizing each sample in a frequency range 100 Hz–1 MHz and a temperature range 300–400 K. Two formalisms were used to analyze the data: (a) the electrical conductivity which has found to follow the Jonscher’s law with single and double exponents for carbon nanotube concentrations below and above the percolation threshold, respectively, and (b) the complex impedance that has permitted to identify the relaxation peaks according to the Cole–Cole model. Both the two formalisms showed that when the carbon nanotube concentration is higher than the percolation threshold, a positive temperature coefficient and a remarkable change in conductivity were observed, suggesting that the presence of t...

Journal of Semiconductors

Journal of King Saud University - Science