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El Hafid H.,CNRS Laboratory of Condensed Matter Chemistry, Bordeaux | Velazquez M.,CNRS Laboratory of Condensed Matter Chemistry, Bordeaux | Perez O.,CNRS Crystallography and Material Science Laboratory | El Jazouli A.,Laboratoire Of Chimie Des Materiaux Solides | And 5 more authors.
European Journal of Inorganic Chemistry | Year: 2011

A new oxyphosphate, PbFe3O(PO4)3, has been discovered and its structure has been characterized by single-crystal XRD between 293 and 973 K (monoclinic, space groupP21/m, a = 7.5826 Å, b = 6.3759 Å, c = 10.4245 Å, β = 99.956°, Z = 2, at r.t.). Direct-current (DC) magnetic susceptibility and specific heat measurements performed on single crystals revealed an unusual sequence of second-order ferromagnetic-like phase transitions at Tc1 = 31.8 K, Tc2 = 23.4 K and Tc3 â 10 K. Alternating-current (AC) magnetic susceptibility measurements suggest glass-like dynamics between ca. 20 K and Tc3. A new oxyphosphate, PbFe3O(PO4)3, has been discovered and its structure has been characterized by single-crystal XRD. Direct-current (DC) magnetic susceptibility and specific heat measurements performed on single crystals revealed an unusual sequence of second-order ferromagnetic-like phase transitions. Alternating-current (AC) magnetic susceptibility measurements suggest glass-like dynamics. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source


El Hafid H.,CNRS Laboratory of Condensed Matter Chemistry, Bordeaux | Velazquez M.,CNRS Laboratory of Condensed Matter Chemistry, Bordeaux | Perez O.,CNRS Crystallography and Material Science Laboratory | El Jazouli A.,Laboratoire Of Chimie Des Materiaux Solides | And 5 more authors.
Journal of Solid State Chemistry | Year: 2013

The PbFe3O(PO4)3 powder compound was studied by means of X-ray diffraction (XRD) from 300 to 6 K, electron-probe microanalysis (EPMA) coupled with wavelength dispersion spectroscopy (WDS), calorimetric (DSC and specific heat) and magnetic properties measurements. Magnetization, magnetic susceptibility and specific heat measurements carried out on PbFe3O(PO4)3 powders firmly establish a series of three ferromagnetic (FM)-like second order phase transitions spanned over the 32-8 K temperature range. Discrepancies between magnetization and specific heat data obtained in PbFe3O(PO4)3 powders and single crystals are highlighted. A first extraction of the critical exponents (β,γ,δ) was performed by ac magnetic susceptibility in both PbFe3O(PO4)3 powders and single crystals and the values were found to be consistent with mean-field theory. Further exploration of the PbO-Fe2O3-P2O 5 system led to the discovery of a new langbeinite phase, Pb 1.5Fe2(PO4)3, the crystal structure of which was solved by room temperature single crystal XRD (P213, Z=4, a=9.7831(2) Å). This phase does not undergo any structural phase transition down to 6 K nor any kind of long range ordering down to 2 K. © 2013 Elsevier Inc. Source


Essehli R.,Ecole des Mines de Nantes | Essehli R.,University Mohammed Premier | El Bali B.,University Mohammed Premier | Faik A.,CIC ENERGIGUNE | And 6 more authors.
Journal of Alloys and Compounds | Year: 2012

Nickel titanium oxyphosphate Ni 0.5TiOPO 4 (NTP), was prepared by co-precipitation route. Its structure was determined by single crystal X-ray diffraction. The compound crystallizes in the monoclinic system, S.G: P2 1/c [a = 7.333(1), b = 7.316(2), c = 7.339(2), β = 119.62(3)°, Z = 4, R 1 = 0.0142, wR 2 = 0.0429]. The structure might be described as a {TiOPO 4} framework made of corner-sharing [TiO 6] octahedra chains running parallel to [0 0 1] and cross linked by phosphate [PO 4] tetrahedral, where half of octahedral cavities created are occupied by Ni atoms, and the other half of octahedral sites are vacant. During the first discharge, the NTP electrode delivered a capacity of 530 mAh/g, upon cycling within 0.5-4 V. To understand the electrochemical reaction mechanism using different characterization techniques viz. in situ synchrotron diffraction. Reciprocal magnetic susceptibility (χ -1) of NTP, between 4 and 300 K, shows an almost linear behavior and can be fitted by the simple Curie-Weiss law. © 2012 Elsevier B.V. All rights reserved. Source


Bih L.,British Petroleum | Bih H.,British Petroleum | Amalhay M.,Direction Recherche and Developpement | Mossadik H.,Direction Recherche and Developpement | And 4 more authors.
Procedia Engineering | Year: 2014

As the increasing demands of compact and space-saving electronics, capacitors with high energy-storage density are eagerly desired. One of the greatest challenges in the development of new high energy density materials is to increase dielectric permittivity. In this present work, we present some first results relative to phosphate glasses, which could be used as the dielectric energy-storage materials to fabricate high energy density devices. They were prepared by means of rapid quenching method. DTA and X-ray diffraction analysis were used to control their vitreous states. Dielectric constant of the glasses was measured at the frequency from 1Hz to 1MHz under the testing temperature from 120 K to 360 K. The results indicated that some samples exhibit high dielectric properties. © 2014 The Authors. Source


Sinouh H.,British Petroleum | Bih L.,Equipe science de la Matiere Condensee | El Bouari A.,Laboratoire Of Chimie Des Materiaux Solides | Azrour M.,British Petroleum | And 2 more authors.
Journal of Non-Crystalline Solids | Year: 2014

The glasses in the Na2O-SrO-BaO-TiO2-B2O3-P2O5system were prepared by the conventional quenching route. In the present work, we studied the effect of BaSr substitution on some physical parameters such as density, molar volume, micro-hardness, glass transition temperature (Tg), and crystallization temperature (Tc) of series of glasses with the following composition 33.33Na2O-(10 - x)SrO - xBaO-10TiO2-30B2O3-16.67P2O5. The crystallization of the glasses by heat-treatments is performed and X-ray diffraction (XRD) showed the formation of a ferroelectric phase SrTiO3and Na4Ba2(PO3)6in their network. The kinetic of the crystallization is carried out by using DSC technique, and the activation energy and the Avrami parameter (n) are determined. © 2014 Published by Elsevier B.V. Source

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