Laboratory of Coordination Chemistry

Toulouse, France

Laboratory of Coordination Chemistry

Toulouse, France
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Sbissi K.,University of Sfax | Kahn M.L.,Laboratory of Coordination Chemistry | Ellouze M.,University of Sfax | Elhalouani F.,University of Sfax
Journal of Superconductivity and Novel Magnetism | Year: 2015

This paper studies the effects of the Mn site substitution by Fe on the magnetic properties and the magnetocaloric properties of Pr0.8Bi0.2FexMn1−xO3 elaborated by a sol–gel method. The variation of the magnetization as a function of temperature and applied magnetic field was carried out. Magnetic measurements show that all the materials exhibit a paramagnetic–ferromagnetic transition when the temperature decreases. The dependence of the Curie temperature (TC) and the magnetic entropy change (ΔSM) when varying the Fe doping content was investigated. The measured value of TC was 114, 97, 94, and 77 K for x = 0, 0.1, 0.2, and 0.3, respectively. The samples with x = 0 and x = 0.1 present a second-order phase transition, while the samples with x = 0.2 and x = 0.3 exhibit a first-order phase transition. As the concentration of Fe increases, the maximum entropy change,(Formula presented.), decreases gradually, from 2.77 J kg−1 K−1 (x = 0) to 1.05 J kg−1 K−1 (x = 0.3), when the magnetic field changes from 0 to 5 T. © 2015, Springer Science+Business Media New York.


Sbissi K.,University of Sfax | Kahn M.L.,Laboratory of Coordination Chemistry | Ellouze M.,University of Sfax | Hlil E.K.,CNRS Neel Institute | Elhalouani F.,University of Sfax
Journal of Superconductivity and Novel Magnetism | Year: 2015

The magnetic and magnetocaloric properties of Pr1−xBixMnO3 (x = 0.2 and 0.4) nanocrystalline manganites have been studied systematically. Samples were prepared using the Pechini sol–gel method. The variation of the magnetization as a function of temperature and applied magnetic field were carried out. Magnetic measurements show that all the materials exhibit a paramagnetic–ferromagnetic transition when the temperature decreases. Magnetocaloric effect has been calculated in terms of isothermal magnetic entropy change. A large magnetocaloric effect has been observed, the maximum entropy change, (Formula presented.)reaches 0.7 and 2.1 J kg−1 K−1 under a magnetic applied field of 5 T with an RCP values of 183 J kg−1 for Pr0.8Bi0.2MnO3 sample. These perovskites have the large magnetic entropy changes induced by low magnetic field change, which is beneficial for the household application of active magnetic refrigerant (AMR) materials. © 2015, Springer Science+Business Media New York.


Essalah K.,British Petroleum | Sanhoury M.A.,Laboratory of Coordination Chemistry | Ben Dhia M.T.,Laboratory of Coordination Chemistry | Abderrabba M.,British Petroleum | Khaddar M.R.,Laboratory of Coordination Chemistry
Journal of Molecular Structure: THEOCHEM | Year: 2010

Tin tetrachloride adducts of the type SnCl4·2L (L = (Me2N)3P(O) (1), (Me2N)2P(O)F (2), Me2NP(O)F2 (3) and P(O)F3 (4)) have been theoretically studied by means of DFT geometry optimisation (B3LYP/LANL2DZ) and 119Sn chemical shift calculations (B3LYP/SV). A good correlation was found between calculated and experimental data. On going from complex 1 to 4, the Sn{single bond}L bond underwent considerable lengthening, while that of Sn{single bond}Cl was shortened (Sn{single bond}O: 2.11 in cis-1 vs. 2.37 Å in cis-4; Sn{single bond}Cl: 2.43 in cis-1 vs. 2.37 Å in cis-4). In the same way, the Sn{single bond}O{single bond}P bond angle was found to decrease from 147° for cis-1 to 136° for cis-4. The trends are in good agreement with the calculated metal-ligand binding energies of complexes 1-4. Interestingly, the structural changes are accompanied by increased 119Sn chemical shifts towards higher frequencies as the Me2N groups in the ligand are substituted by fluorine atoms. The theoretical results showed that the use of the all-electron SV basis set for tin, together with the 6-31G* basis set for the other atoms could efficiently predict the 119Sn NMR chemical shifts in the complexes SnCl4·2L. © 2009 Elsevier B.V. All rights reserved.

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