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Bekri-Abbes I.,Center National Of Recherches En Science Des Materiaux | Srasra E.,Center National Of Recherches En Science Des Materiaux
Journal of Polymer Research | Year: 2011

Conductive polyaniline has been prepared by solid-solid reaction using ammonium peroxydisulfate as an oxidant. The obtained polymer was examined by X-ray diffraction, UV visible, FTIR spectroscopy, thermogravimetric analysis and impedance spectroscopy. The effect of oxidant/monomer molar ratio (R) on the structure and electrical properties of polymer has been examined. The analyses of X-ray diffraction patterns demonstrated that polyaniline prepared by this method is more crystalline than that obtained by conventional solution method. The FTIR spectroscopy showed that the emeraldine salt has been formed. The electrical properties were measured at different temperatures in the range of 296-523 K. The ac conduction shows a regime of constant dc conductivity at low frequencies and a crossover to a frequency-dependent regime of the type A ωS at high frequencies. © 2010 Springer Science+Business Media B.V. Source


Sdiri N.,University of Monastir | Elhouichet H.,Center National Of Recherches En Science Des Materiaux | Azeza B.,University of Monastir | Mokhtar F.,Center National Of Recherches En Science Des Materiaux
Journal of Non-Crystalline Solids | Year: 2013

Glass systems of composition (90-x) P2O5 + xB 2O3 + 10Fe2O3 (x = 0 mol.%, 10 mol.%, 20 mol.%, 30 mol.%, 40 mol.%) were prepared using normal melt-quench technique. The Mossbauer Effect has been used intensively to help investigate the structure and bonding of oxide glasses. The Mössbauer spectra indicate the presence of iron (II) and iron (III) in tetrahedral or octahedral coordination. The dependence of electrical data was analyzed in the frame work of the impedance Cole-Cole plot in a frequency range from 5 Hz to 19.5 MHz at room temperature. Constant-phase elements (CPE) are used in equivalent electrical circuits for the fitting of experimental impedance data. The frequency dependence of the electric conductivity was found to follow a simple power law behavior, in accordance with the relation σ(f) = σ(0) + Af s, where s is smaller than 1. The thermal activation energies for the electronic conduction were estimated on the basis of the Arrhenius plots. © 2013 Elsevier B.V. Source


Stambouli W.,Center National Of Recherches En Science Des Materiaux | Elhouichet H.,Center National Of Recherches En Science Des Materiaux | Elhouichet H.,University of Tunis | Gelloz B.,Nagoya University | Ferid M.,Center National Of Recherches En Science Des Materiaux
Journal of Luminescence | Year: 2013

Tellurite glasses doped with trivalent europium were prepared by the conventional melt quenching technique, in the chemical composition of (85-x) TeO2+5La2O3+10TiO2+xEu 2O3 by varying the concentration of the rare-earth ion in the order 0.5, 1 and 1.5 mol%. Using Judd-Ofelt analysis, we calculated intensity parameters (Ω2 and Ω4), spontaneous emission probabilities, the radiative lifetime, luminescence branching factors, the quantum yield of luminescence, and the stimulated emission cross-sections for 5D0→7F2 transition. The change in optical properties with the variation of Eu3+ ion concentration have been discussed and compared with other glasses. The luminescence intensity ratio, quantum efficiency and emission cross-section values support that the TeEu1.5 tellurite glass is a suitable candidate for red laser source applications. Optical properties for Eu3+ doped tellurite glass, heated for different temperature, were investigated. Crystalline phases for α-TeO2, γ-TeO2 and TiTe3O8 system were determined by the XRD method. The effect of heat treatment on luminescence properties in the tellurite glass was discussed. By using Eu3+ as a probe, the local structure of rare-earth ion in tellurite glass, vitro-ceramic and ceramic glass has been investigated. The evaluated J-O intensity parameters have been used to calculate different radiative and laser characteristic parameters of the 5D0 excited level. The large magnitudes of stimulated emission cross-section (σe), branching ratio (β) and Gain bandwidth (σe×Δλeff) obtained for 5D0→7F2 (613 nm) transition for ceramic glass indicate that the present glass ceramic is promising host material for Eu3+doped fiber amplifiers. The measured lifetime of 5D0 excited state increases with increase of the heat treatment which further indicate that some Eu3+ ions were successfully embedded in the crystal phase and prove the low phonon energy environment of Eu3+ ions in the nanocrystals precipitated in the glass ceramics. © 2013 Elsevier B.V. Source


Sdiri N.,Center National Of Recherches En Science Des Materiaux | Elhouichet H.,Center National Of Recherches En Science Des Materiaux | Ferid M.,Center National Of Recherches En Science Des Materiaux
Journal of Non-Crystalline Solids | Year: 2014

Abstract In this paper a set of (95-x) P2O5-xB 2O3-4.9Na2O-0.1Er2O3 (x = 5-10-15-20 mol%) samples was prepared using a conventional melt-quenching technique. A glass ceramic phase was confirmed by X-ray diffraction. Small crystallites at the B2O3 addition were detected by Raman scattering. The glass containing 20 mol% B2O3 shows a high thermal stability with a value ΔT = Tc-Tg exceeding 100 C, where Tg and Tc are the glass transition and crystallization onset temperatures. The Raman spectroscopy measurement shows that BOP bonds were present in the glasses. From the absorption edge studies, the value of the optical band gap Eopt has been evaluated. The decrease in optical band gap values and consequently the decrease in Urbach's energies confirm the less extension of the localized states within the band gap. As a result, there shall be an increase in the order of the glass network. The variation in optical parameters is owing to the substitution of B 2O3 oxides in P2O5-Na 2O-Er2O3 glass network. The fundamental absorption edge for all the glasses was analyzed and the Judd-Ofelt parameters (Ω2, Ω4 and Ω6) were obtained. The PL intensity, the PL life time and the quantum efficiency relative to the 4I13/2 → 4I15/2 (1530 nm) transition of Er3 + were all found to decrease with the addition of B2O3. © 2014 The Authors. Source


Sdiri N.,Center National Of Recherches En Science Des Materiaux | Elhouichet H.,Center National Of Recherches En Science Des Materiaux | Barthou C.,CNRS Nanosciences Institute of Paris | Ferid M.,Center National Of Recherches En Science Des Materiaux
Journal of Molecular Structure | Year: 2012

In this work, Judd-Ofelt analysis is applied to an extensive series of Er 3+-doped and Er 3+, Yb 3+-codoped in phosphate-borate glass in order to evaluate their potential as both glass laser systems and amplifier materials. A spectroscopic investigation is presented. The phenomenological Judd-Ofelt parameters Ω 2, Ω 4 and Ω 6 are determined for both rare-earth ions together with their quality factors and compared to the equivalent parameters for other host glasses. The absorption cross section for the 4I 13/2→ 4I 15/2 transition is determined. Photoluminescence (PL) and its decay behaviour studies were carried out for the transition 4I 13/2→ 4I 15/2. © 2011 Elsevier B.V. All rights reserved. Source

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