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Manoun B.,Hassan 1er University | Ezzahi A.,Hassan 1er University | Benmokhtar S.,Laboratoire Of Recherche Of Chimie Physique Generale Des Materiaux | Ider A.,Hassan 1er University | And 3 more authors.
Journal of Alloys and Compounds | Year: 2012

X-ray diffraction and Raman spectroscopy studies of Sr doped double perovskites compound Ba 2-xSr xZnWO 6 with (0 ≤ x ≤ 2) were investigated. As a function of composition while increasing strontium amount, the samples show two phase transitions from cubic to tetragonal phase and from tetragonal to monoclinic structure. Both Rietveld refinements and Raman studies showed that the first phase transition occurs between x = 1 and 1.2; the second phase transition is observed around x = 2. Furthermore, increasing the temperature for the compositions (1.2 ≤ x < 2), manifests the tetragonal to cubic phase transition. For x = 2 two phase transitions were observed as a function of temperature. For this series, the phase transitions are illustrated by considerable changes in the composition and temperature dependence of the modes. All the Raman modes show a linear behavior when the composition or temperature is increased, then the slope change indicating the symmetry change. © 2012 Elsevier B.V.


Manoun B.,Hassan 1er University | Ezzahi A.,Hassan 1er University | Benmokhtar S.,Laboratoire Of Recherche Of Chimie Physique Generale Des Materiaux | Bih L.,Laboratoire Of Physico Chimie Des Materiaux | And 6 more authors.
Journal of Molecular Structure | Year: 2013

X-ray diffraction and Raman spectroscopy studies of Sr doped double perovskites compound Ba2-xSrxMWO6 with (M = Ni, Co and 0 ≤ x ≤ 2) were investigated. The samples show a transition from cubic to tetragonal phase as a function of composition while increasing strontium amount; both Rietveld refinements and Raman studies showed that this transition occurs between x = 1.2 and 1.4. Furthermore, increasing temperature for the tetragonal compositions (1.4 ≤ x ≤ 2), manifest the tetragonal to cubic phase transition. For this series, the transition from tetragonal (I4/m)/to cubic (Fm-3m) shows considerable changes in the composition and temperature dependence of the modes: all the Raman modes show a linear behavior when temperature is increased, then the slope change dramatically indicating the symmetry change from tetragonal to cubic. To better view this phase transition, the full width at half maximum (FWHM) temperature dependence of the most intense modes were studied; by this study, we have obtained a sensitive guide to the onset of the phase transition. A large increase of the FWHM with increasing temperature is observed for all modes in the spectrum, clear transitional effects were observed: the width behaves in a linear way as a function of temperature; when the temperature reached the transition temperature, a drop in the width of this mode was observed. © 2013 Elsevier B.V. All rights reserved.


Azrour M.,Laboratoire Of Physico Chimie Des Materiaux | Azdouz M.,Laboratoire Of Physico Chimie Des Materiaux | Azdouz M.,Laboratoire Of Recherche Of Chimie Physique Generale Des Materiaux | Manoun B.,Hassan 1er University | And 7 more authors.
Journal of Physics and Chemistry of Solids | Year: 2011

Synthesis of apatites, Na1-xKxPb4(PO 4)3 0≤x≤1, with anion vacancy was carried out using solid state reactions. The solid solution of apatite-type structure crystallizes in the hexagonal system, space group P63/m (No 176). Rietveld refinements showed that 75% of Pb2 cations are located in the (6h) sites; the ninefold coordination sites (4f) are equally occupied by the other 25% lead cations and the K and Na monovalent ions. The structure can be described as built up from [PO4]3- tetrahedra and Pb 2 of sixfold coordination cavities (6h positions), which delimit void hexagonal tunnels running along [0 0 1]. These tunnels are connected by cations of mixed sites (4f) half occupied by Pb2 and half by Na/K mixed cations. The assignment of the observed frequencies in the Raman and infrared spectra is discussed on the basis of a unit cell group analysis and by comparison with other apatites. The Raman modes of all the compositions show some linear shifts of the frequencies as a function of the composition toward lower values due the substitutions of Na by K with a larger radius. © 2011 Elsevier Ltd. All rights reserved.


Ouasif H.,Laboratoire Of Chimie Analytique Physico Chimie Des Materiaux | Yousfi S.,Laboratoire Of Chimie Analytique Physico Chimie Des Materiaux | Bouamrani M.L.,Laboratoire Of Chimie Analytique Physico Chimie Des Materiaux | El Kouali M.,Laboratoire Of Chimie Analytique Physico Chimie Des Materiaux | And 2 more authors.
Journal of Materials and Environmental Science | Year: 2013

The aim of this study is the elimination of methylene blue from waste water by adsorption on clays and oil shales. These natural materials are decarbonated with hydrochloric acid and characterized by X-ray diffraction X-ray fluorescence and infrared spectroscopy. Factors affecting adsorption were evaluated. Kinetic parameters calculated from the experimental data could be fitted to a pseudo-second-order kinetic model. The equilibrium of adsorption and the adsorption data are well described by the Langmuir model. Clays absorb more methylene blue than oil shales. The sorbents treated with hydrochloric acid have higher capacity than the starting materials.

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