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Dhaouadi H.,Laboratoire des Utiles | Dhaouadi H.,Institute National Of Recherche Et Danalyse Physicochimique | Fadhalaoui A.,Laboratoire Materiaux et Environnement | Mdani A.,University of Umm Al - Qura | Rzaigui M.,Laboratoire Materiaux et Environnement

Cerium phosphate nanomaterials with different morphologies and sizes were synthesized via a hydrothermal process at 150 °C using cetyl-trimethyl-ammonium-bromide and ethylene-diamine-tetra acid as surfactants. The obtained samples were characterized by X-ray diffraction and a scanning electron microscope. A possible growth mechanism was proposed to reveal the formation process. The structural properties and the electrical conductivities of CePO4 nanomaterials were studied. The activation energies were obtained from Arrhenius plots where E a = 1.06 eV. The ac conductivity at different temperatures for CePO4 nanomaterials showed frequency independence in the lower frequency range. The dielectric measurements were carried out as a function of frequency and temperature. Variation of the dielectric properties and the ac conductivity with frequency revealed that the dispersion is due to a Maxwell-Wagner type of interfacial polarization in general. © 2013 Springer-Verlag Berlin Heidelberg. Source

Dhaouadi H.,Institute National Of Recherche Et Danalyse Physicochimique | Kouass S.,Institute National Of Recherche Et Danalyse Physicochimique | Jaouad N.,Institute National Of Recherche Et Danalyse Physico Chimique Sidi Thabet | Ghodbane O.,Institute National Of Recherche Et Danalyse Physicochimique | Touati F.,Institute National Of Recherche Et Danalyse Physicochimique
Materials Research Bulletin

The nanostructured pyrophosphate Ni0.25Co0.75MnP 2O7 was prepared. The synthesis technique was based on the hydrothermal method at 150 C using poly-ethylene-glycol (PEG-10000) as surfactant with further calcination at 500 C. A structural analysis of Ni 0.25Co0.75MnP2O7 compound was carried out by applying X-ray diffraction (XRD) and using the Rietveld method. Morphological characterizations were performed using a scanning electron microscope (SEM) and transmission electron microscopy (TEM). A comparative study of the electrical conductivity of Mn2P2O7 and Ni0.25Co0.75MnP2O7 nanomaterials was carried out by impedance spectroscopy in the temperature range 500-680 C. The activation energies for MnP2O7 and Ni 0.25Co0.75MnP2O7 were 2.00 and 0.88 eV, respectively. Ni0.25Co0.75MnP2O7 nanomaterial presents a good electric conductivity compared to Mn 2P2O7, due to the substitution effect. The improvement of the electronic and ionic conductivity makes the Ni 0.25Co0.75MnP2O7 nanomaterial possible electrode materials for rechargeable batteries. The electrochemical behaviors of Ni0.25Co0.75MnP2O7 were studied using cyclic voltammetry. © 2013 Published by Elsevier Ltd. Source

Baazaoui M.,UR Physico Chimie des Materiaux Solides | Baazaoui M.,University of Carthage | Bejaoui I.,UR Physico Chimie des Materiaux Solides | Bejaoui I.,University of Carthage | And 4 more authors.
Colloids and Surfaces A: Physicochemical and Engineering Aspects

Aminoalkyl derivatives of β-cyclodextrin, in their neutral form are insoluble amphiphilic cyclodextrins that could be dispersed as nanoparticles in water. Such nanoparticles solubilize host molecules either in the non-polar medium in between the alkyl chains or in an environment of medium polarity inside the hydrophobic cavity of the cyclodextrins. This allows the solubilization of a wider range of molecules such as drugs, fragrances, aromas. . . than classical nanoparticles containing either oil or polymer. A series of such compounds either mono- or per-substituted at the C6 methylene of the β-CD primary rim with either short butyl chain or long dodecyl chain are obtained by chemical modification of native β-cyclodextrin with aminoalkyl groups. Their physicochemical properties and utilization for the manufacture of nanoparticles have been studied. The solubility assessed from direct microscopy observation and surface tension measurements were low; they were related to the hydrophobic character of the amphiphilic β-CDs, that is, the number and length of their alkyl chains. The monobutyl derivative adsorbs at the air-water interface as a monolayer whereas the most hydrophobic derivatives collapses into a 3-dimensional adsorbed layer. Stable nanoparticles were prepared by means of dispersion by ultrasound or by the nanoprecipitation method. Sonication yielded large and polydisperse nanoparticles of size larger than 500 nm; nanoprecipitation resulted in the formation of small nanoparticles with sizes in the range 100-200 nm with a narrow particle size distributions. © 2015 Elsevier B.V. Source

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