Résumé:
Conclusion
Générale
98
Abstract:
At this stage of o
ur study on the ternary system:
Pb
1
-
x
La
z
Ca
x
[(Zr
y
Ti
1
-
y
)
0,75
(Sb)
0,25
]O
3
.
It seems necessary to draw some conclusions and confirm certain assumptions we have
made progress. Interest presented by the piezoelectric ceramic
PZT
type led us to synthesize
new materials
.
First, we studied the morphology of
PZT
ceramics of the solid solution of lead zirconate
titanate, using a differential scanning calorimetry (
DSC
) and differential thermal analysis
(
DTA
). We determined the mechanism forming reaction of the solid solution in the presence
of
PZT
base oxides
PbO, Z
rO
2
, TiO
2
and doping oxides
La
2
O
3
, CaCO
3
and
Sb
2
O
3
.
The mechanism is
follow
ing
:
3 PbO
Pb3O4
(1)
Pb
3
O
4
3 PbO + O
2
(2)
PbO + TiO
2
PbTiO
3
(3)
PbTiO
3
+ ZrO
3
PZT
(4)
The temperature of formation of lead zirconate titanate (
PZT
) is about
700 °
C
. This is
associated with the diffusion of
Zr
+4
and
Pb
+2
in the structure of perovskite lead titanate u
p
to saturation.
Subsequently, the sample sintered at a temperature of
1180 °
C
has a density close to
theoretical de
nsity.
We as note, as the addition of the doping agents increases the density for
the unit of the
doped samples of
1%
up to
5%
, this thickening is characterized by a reduction in porosity.
What means that the volume of the mesh decreases, the structure becomes compact.
By the method of analysis of diffraction of X
-
ray, we determined the border mor
pho
-
tropic of phase (Tétragonal + Rhomboédral
) in piezoelectric ceramics of type PZT in the
presence of the oxides
La
2
O
3
, CaCO
3
and
Sb
2
O
3
. The effect of the doping agents on the
density and the porosity of solid solution
PZT
-
LCS
were
studied. It was noted that the shape
of the curve of porosity is the reverse of that of the density, the packing implies a reduction in
the number and dimensions of the pores, therefore the volume of
the mesh decreases and
consequently the structure becomes more compact.
Lastly, we characterized these new piezoelectric materials by their physical properties
such as the temperature of Curie, permittivity, the loss angle and the resistivity according to
the various temperatures of sintering and freque
