Controle 4 Nasicon BENMOKHTAR .pdf


Nom original: Controle 4_Nasicon_BENMOKHTAR.pdf
Titre: Durée de l’examen : 1h30

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Name : …………………………………………
UNIVERSITE HASSAN II – MOHAMMEDIA
FACULTE DES SCIENCES BEN M'SIK
CASABLANCA
DÉPARTEMENT DE CHIMIE
-----------MASTER GENIE DE MATERIAUX
Module Stratégie de synthèse des matériaux
Semestre 1
Pr. Said BENMOKHTAR

November 2012

Exam N°4 ( 20 min )
The structure of Nasicon-type phosphates Mn0.5Zr2(PO4)3 consists of a three-dimensional
network formed by PO4 tetrahedra sharing corners with ZrO6 octahedra. The site occupied by
sodium is an elongated antiprism formed by triangular faces of two ZrO6 octahedra along the
c axis of the hexagonal cell. This site is usually called M(1). The phosphozirconate
framework also creates a large tenfold coordinated site called M(2). Every M(1) site is
surrounded by six M(2) sites sharing common triangular faces.
Mn0.5Zr2(PO4)3 was prepared from stoichiometric proportions of Mn (Cerac, 99.95%) as metal
and ZrOCl2.8H2O (Merck, 99%) were respectively dissolved in 2.5 N HNO3 and water. The
solutions were then mixed. The addition of a solution of (NH4)2HPO4 (Merck, 99.5%) in
appropriate proportion, under constant stirring, produced a colorless gel, which was heated at
80°C for 24 h. The obtained powder was successively heated at 400, 600, 700, and 900°C in
an alumina crucible, with intermediate grinding.
Figure1 shows the typical diffraction peaks of the Nasicon Mn0.50Zr2(PO4)3, especially the
first nine peaks at 2θ = 12.23 º, 14.13 º, 20.02 º, 23.51 º, 28.64 º, 31.09 º, 31.83 º,and 35.06º,
which can be indexed as (101), (012), (110), (113), (024), (211) , (116) and (300),
respectively. The wavelength of incoming radiation was 1,5405Å. The indexation of all
reflections is consistent with the R3 space groups. The density dexp=3.31g/cm3
Figure 1

1) Describe the method used in the synthesis of this compound, and gives its advantages and
disadvantages.
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FSB_ MASTER GENIE DE MATERIAUX

Année Universitaire 2012-2013

2) Determine the lattice parameters a and c of the Nasicon Mn0.50Zr2(PO4)3.
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3) Determine the formulae per cell Z of the Nasicon Mn0.50Zr2(PO4)3.

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4) Briefly describe the principles of this technique bellow figure 2, and the magnetic
behaviour of responsible ion the Nasicon Mn0.50Zr2(PO4)3.
Figure 2

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5) Gives a brief description of the structure of the Nasicon Mn0.50Zr2(PO4)3, complete the
figure 3 and show the two type sites M(1) and M(2) and gives de coordination number of this
two types sites .
Figure 3
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FSB_ MASTER GENIE DE MATERIAUX

Année Universitaire 2012-2013


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