Laboratoire Of Chimie Physique Des Materiaux Lcpm

Casablanca, Morocco

Laboratoire Of Chimie Physique Des Materiaux Lcpm

Casablanca, Morocco
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Ait Haddouch M.,Laboratoire Of Chimie Physique Des Materiaux Lcpm | Aharbil Y.,Laboratoire Of Chimie Physique Des Materiaux Lcpm | Tamraoui Y.,Hassan 1er University | Manoun B.,Hassan 1er University | And 2 more authors.
Journal of Materials and Environmental Science | Year: 2015

In this work, we report on the synthesis of Barium Strontium Tungstate (Ba1-xSrx)WO4 powders with (x = 0 ; 0.25 ; 0.5 ; 0.75 and 1.0). The obtained powders were analyzed by X-ray diffraction (XRD), Raman spectroscopy and also optimised by Density functional theory (DFT) calculations. XRD patterns showed that (Ba1-xSrx)WO4 powders present a scheelite-type tetragonal structure. Rietveld refinements showed that the samples crystallized with tetragonal symmetry, S.G. I41/a. and lattice parameters : a~ 5.07 Å and c~ 11.6 Å. The scheelite structure can be represented by WO4 tetrahedra isolated from each other and connected by the summits with Ba-and Sr-polyhedrons. Raman spectra proved the evidence of a tetragonal structure due to W-O antisymmetric stretching vibration into the [WO4] tetrahedron groups. Density functional theory (DFT) using the Plane-Wave Self-Consistent Field (PWscf) with generalized gradient approximation (GGA) were carried out for the scheelite materials (Ba1-xSrx)WO4 in order to determine their ground-state electronic properieties.The results indicate a decreases in the values of the optical direct band gap (from 4.67 to 4.38 eV) with the increase of Sr into BaWO4 lattice.


Aharbil Y.,Laboratoire Of Chimie Physique Des Materiaux Lcpm | Labrim H.,Mohammed V University | Benmokhtar S.,Laboratoire Of Chimie Physique Des Materiaux Lcpm | Ait Haddouch M.,Laboratoire Of Chimie Physique Des Materiaux Lcpm | And 2 more authors.
Materials Research Express | Year: 2016

This work aims to study the double perovskites A2NiMoO6 (A=Ba, Sr) by using the first principle calculation, within the framework of the self-consistent Hubbard correction. The value of this correction, for Ni andModepends strongly on the type of the studied compounds. Such values are determinate as 7.35 eV for Ni and 5.42 eV forMoin the compound Ba2NiMoO6, whereas in the case of Sr2NiMoO6 the calculated values are 8.71 eV and 5.48 eV for Ni andMocompound respectively. Based on the densities of state calculation we show that both the compounds are semiconductors with gap energies of 2.20 eV and 2.10 eV for Ba2NiMoO6 for Sr2NiMoO6, respectively. The total energies comparison shows clearly that the ground state is G-type anti-ferromagnetic order in agreement with experimental results, the magnetic interactions are due to the super-exchange mechanism acting in long range via hybridization throw Ni-O-Mo-O-Ni path.

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