Materials Sciences and Applications, 2013, 4, 746-750
Published Online November 2013 (http://www.scirp.org/journal/msa)
http://dx.doi.org/10.4236/msa.2013.411094
Open Access MSA
Synthesis and Dielectric Properties of
(0.80 − x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3
Ferroelectric Ceramics
Abdelhek Meklid1*, Ahmed Boutarfaia1,2, Zelikha Necira1, Hayet Menasra1, Malika Abba1
1Laboratory of Applied Chemistry, Materials Science Department, Mohamed Kheider University of Biskra, Biskra, Algeria; 2Uni-
versity of Ouargla, Ouargla, Algeria.
Received September 16th, 2013; revised October 21st, 2013; accepted November 3rd, 2013
Copyright © 2013 Abdelhek Meklid et al. This is an open access article distributed under the Creative Commons Attribution License,
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Perovskite PZT variants were synthesized from stoichiometric oxide ratios of Pb, Zr, Ti, Cr, Ni and Sb. The oxide
powders were mixed mechanically and calcinated, and then sintered to form the desired perovskite phase. The detailed
structural and ferroelectric properties were carried out for sintered specimens. The results of X-ray diffraction showed
that all the ceramics specimens have a perovskite phase. The multi-component ceramic system consists of the (0.80 −
x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 (PZT-CNS), with 0.30 ≤ x ≤ 0.42, and the ternary system near the
rhombohedral/tetragonal morphotropic phase boundary(MPB) was investigated by X-ray diffraction and dielectric
properties. In the present system, the MPB that coexists with the tetragonal and rhombohedral phases is a narrow com-
position region of x = 0.38 - 0.42. The scanning Electron Microscopy (SEM) showed an increase of the mean grain size
when the sintering temperature was increased. A sintered density of 92.93% of the theoretical density was obtained for
Ti = 42% after sintering at 1180˚C. Ceramics sintered at 1180˚C with Ti = 42% achieve excellent dielectric properties,
which are as follows εr = 4262.48, and Tc = 340˚C.
Keywords: PZT; Calcination; Dielectric Properties; MPB; Ceramic; X-Ray Methods
1. Introduction
Lead zirconate titanate (PZT) with the perovskite struc-
ture is the most popular ferroelectric material, which
plays a remarkable role in modern electroceramic indus-
try [1]. Moreover, PZT has high dielectric constant, high
electromechanical coupling and high piezoelectric coef-
ficient and has been employed as sensors, actuators and
transducers [2-6]. The PZT are often modified by the
introduction of the doping agents into the sites A or/and
in the sites B of perovskite ABO3 structure. The princi-
pal role of the doping agents is generally the improve-
ment of the physical and mechanical properties of these
materials. Substitutions in the crystal lattice called dop-
ing are often led with the aim to improve the specific
properties of the PZT or sometimes to adapt them to spe-
cific applications. These properties are generally im-
proved by the additions of one or more cations which
will replace Pb2+ in site A and/or couple (Zr4+/Ti4+) in
site B of perovskite structure (ABO3) [7]. The selection
of dopants or substitutions to tailor some physical prop-
erties of PZT was based on many factors which are the
following: 1) charge neutrality, 2) tolerance factors, 3)
ionic radius, and 4) solubility/miscibility. However, the
sintering of PZT at high temperatures gives rise to a lead
loss, which drastically degrades the device performance.
Generally, a lead loss at high temperatures can be pre-
vented by atmosphere controlled sintering of PZT. How-
ever, such composition requires sintering at a high tem-
perature (>1250˚C) in a controlled atmosphere to contain
lead volatilization so as to avoid a shift in composition.
To get around the problem, different sintering aids have
been tried by various workers [8-10]. However, for prac-
tical applications, such sintering aids need proper selec-
tion so that the electrical and piezoelectric properties of
the ceramics do not degrade. The width and the proper-
ties of the coexistence region are associated with the oc-
currence of the compositional fluctuation of Ti4+ and Zr4+
*Corresponding author.

Synthesis and Dielectric Properties of (0.80 − x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 Ferroelectric Ceramics 747
ions in the PZT materials [11]. The compositional fluc-
tuation, which is due to a non-uniform distribution of
Titanium and Zirconium ions, leads to a broad variation
in the dielectric constant accompanied with a Titanium
concentration in the MPB region [12]. The width of this
coexistence region and the structure of the PZT ceramics
were greatly affected by the firing time and temperature
[13].
In this study,
(0.80 − x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 pie-
zoelectric ceramics were investigated near the MPB by
varying the ratio of Zr/Ti. The purpose of this work was
to study the phase structure, the dielectric, and the piezo-
electric properties of these ceramics near the MPB in
detail.
2. Experimental Procedure
The compositions used for the present study were (0.80 −
x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 with x va-
rying as 30, 33, 36, 39 and 42 wt% respectively. The
samples were prepared by a conventional oxide mixing
technique. The starting materials were Pb3O4 (99.90%),
ZrO2 (99.90%), TiO2 (99.90%), Cr2O3 (99.6%), Sb2O3
(99.90%) and NiO (99.6%).
Raw materials were mixed in acetone medium by us-
ing a magnetic stirrer during two hours. The obtained
paste is being dried at 80˚C in a drying oven for two
hours, and then crushed in a mortar out of glass during
six hours. After crushing, the obtained powder is com-
pacted in a form of pastilles with a pressure of 300
kg/cm2. Then, a preliminary calcination with 800˚C is
carried out during two hours with a heating rate of
2˚C/mn. The calcined mixture is crushed for a second
time during four hours, and then was quickly crushed in a
form of pellets with a pressure of 1000 kg/cm2. These
pellets are agglomerated at various temperatures of sin-
tering (1100˚C, 1150˚C, 1180˚C, and 1200˚C) during two
hours. It is important to note that a lead loss is possible
by evaporation of PbO which is very volatile in T ≥
900˚C. To limit this effect; an atmosphere rich in PbO
was maintained with the powder of PbZrO3 to the mini-
mum to reduce this loss during sintering. The pastilles
are metalized by using a thin layer of silver paste on the
two faces.
X-ray diffraction (XRD, Siemens D500) was used to
determine the crystalline phases present in the powder.
The compositions of the PZT phases were identified by
the analysis of the peaks [(002)T, (200)R, (200)T] in the
2θ range 43˚ - 46˚. The tetragonal (T), rhombohedral (R)
and tetragonal-rhombohedral phases were characterized
and their lattice parameters were calculated. The rhom-
bohedral lattice parameter was calculated on the assump-
tion that the rhombohedral distortion was constant (unit
cell angle αR = 89.9˚) [14,15]. In order to ensure an ac-
curate determination of the lattice parameters, the X-ray
peaks were recorded gradually with 0.01˚ steps.
Electronic micrographs scanning (SEM) were taken
from fractured as well as chemically etched surfaces. A
section of the sintered sample was etched in a 5% HCl
solution for 3 minutes. The fractured surfaces were used
for grain size and morphology determination. The size
distribution of the grains was measured and the results
compared with each other. The size distribution of the
pores and the total value of porosity were determined on
a polished cross-section of the samples with an image
analyzer. To investigate the electrical properties, the
electrodes were made by applying a silver paste on the
two major faces of the sintered disks followed by a heat
treatment at 750˚C for thirty minutes. The dielectric con-
stant ε was calculated from the capacitance at a fre-
quency of one kHz. It was measured at temperatures
ranging from 25˚C to 450˚C with a heating rate of one
˚C/minute by using an impedance analyzer (HP 4192A,
Hewlett-Packard).
3. Results and Discussion
3.1. Phase Analysis and Microstructure
Sintered powders were examined by X-ray diffractome-
try to ensure phase purity, and to identify the crystal
structure. The coexistence of tetragonal and rhombo-
hedral phases near the morphotropic phase boundary
implies the existence of compositional fluctuations which
can be determined from the width of the X-ray diffrac-
tion peaks. However, determination of the compositional
fluctuation for samples near the morphotropic phase
boundary is difficult. XRD patterns of PZT powders
were analyzed for detecting the characteristic rhombo-
hedral and tetragonal splittings. The (2 0 0) reflections
form a doublet in the tetragonal phase while (1 1 1) is a
singlet. For the rhombohedral phase, (1 1 1) is a doublet
while the (2 0 0) is a singlet. The powder X-ray patterns of
(0.80 − x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 ce-
ramics with different x values are shown in Figure 1. For
x in the range of 0.39 - 0.42, the diagram indicates that a
mixture of phases should be present, which is illustrated
by the (0 0 2) and (2 0 0) tetragonal doublet enclosing the
(2 0 0) rhombohedral line. For x in the range of 0.30 -
0.36 there is a little evidence of the (2 0 0) R peak, indi-
cating a virtually single-phase tetragonal structure. It is
evident from “Figure 1” that as the Ti content increases,
the morphotropic phase becomes more prominent whereas
the tetragonal decreases.
Figure 2(a) shows the variation of density with sinter-
ing temperature. The density increases in the initial pe-
riod with sintering temperature and saturates beyond
1180˚C. From these results, the optimum firing tempera-
ture for the maximum density, ρ, of the ceramic is be-
Open Access MSA

Synthesis and Dielectric Properties of (0.80 − x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 Ferroelectric Ceramics 748
Figure 1. X-ray diffraction patterns of
(0.80 − x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 ceram-
ics sintered at 1180˚C for 2 h with 0.30 ≤ x ≤ 0.42.
Figure 2. Density and porosity versus sintering temperature
of PZT-CNS ceramics (sintering time 2 h).
tween 1150 and 1200˚C. At 1180˚C and Ti = 42%,
92.93% of the theoretical value was achieved. Sintering
at 1200˚C caused the density to decrease. The optimum
value of the sintering temperature was affected by the
additions of impurities and other processing parameters,
such as the rate of heating, time of thermal treatment, and
composition of the protecting atmosphere. The optimum
sintering temperature was taken as the point when the
PbO vapor pressure evaporation-recondensation equilib-
rium for the reaction: PbO-PbO (vapor)-Pb(vapor) + 1/2
O2 was established [16]. Increase of the porosity for tem-
peratures higher than the optimum can, therefore, be at-
tributed to a greater rate of evaporation of PbO compared
to that recondensed. Additions of different oxides to
PZT-type ceramics influence the densification and the
grain size. The process involves a decrease in the number
and size of the pores together with an increase in the
grain sizes. The porosity, determined by means of the
image analyzer as a function of sintering temperature, is
given in Figure 2(b).
Figure 3 shows the lattice constant at room tempera-
ture as function of x. It can be seen that the tetragonal
lattice parameter aT increases linearly with increasing x,
while the cT parameter decreases linearly to a smaller
extent. In all the composition range where the tetragonal
phase is present, cT and aT are closing to gather aT when
Ti content increases, particularly inside the co-existence
region, meaning that the structure is approaching the cu-
bic geometry. The rhombohedral lattice parameter aR
appears to oscillate between 4.023 and 4.024 Å. Accord-
ing to these results, we find that there is a region where
the two phases tetragonal (T) and rhombohedral (R) co-
exist. This region is detected for compositions: Ti = 39%,
Ti = 42%. As against the compositions correspond to Ti
≤ 36%, show that the material obtained is of tetragonal
structure. The influence of the substitution of Zr/Ti ratio
on the structure of the parameters can be explained by
the difference between the ionic rays of Zr and Ti (0.68
and 0.79 Å, respectively). This cannot provide a total
homogeneity in the solid solutions containing both
tetragonal and rhombohedral phases.
Figures 4(a)-(c) shows the SEM images of PZTCNS
(20/36), PZTCNS (20/39) and PZTCNS (20/42) ceramics
sintered at 1180˚C. All the sintered ceramics appear to be
very dense and of a homogeneous granular structure. At
first sight, the three compositions seem homogeneous
and there do not seem to be grains of the pyrochlore
Figure 3. Variation of the unit cell dimensions as a function
of composition (Ti%).
Open Access MSA

Synthesis and Dielectric Properties of (0.80 − x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 Ferroelectric Ceramics 749
(a)
(b)
(c)
Figure 4. Microstructure of (0.80 − x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-
xPbTiO3-0.20PbZrO3 ceramics sintered at 1180˚C for 2 h,
(a) Ti = 36; (b) Ti = 39; (c) Ti = 42.
phase which are identifiable by their pyramidal form.
The ruptures with the grain boundaries are synonymous
with a good sintering. It is noticed that the average di-
ameter of the grains increases significantly with increas-
ing TiO2. The intermediate size of the grains is 1.842 μm
for the sample “Figure 4(a)” with Ti = 36%. For cons,
the intermediate size of sample “Figure 4(b)” of the
grains is larger (2.283 μm). In the case of ceramics “Fig-
ure 4(c)” with Ti = 42%, the intermediate size of the
grains is larger than that of “Figure 4(a)” and “Figure
4(b)” (of the order 2.521 μm); and the broader the
granulo-metric distribution “Figure 4(c)”, the more the
size of the grains gets bigger [17].
3.2. Dielectric Properties
Figure 5 shows the variation of the dielectric constant as
a function: of composition and of temperature at sinter-
ing temperatures 1100˚C, 1150˚C and 1180˚C. For the
three temperatures of sintering 1100˚C, 1150˚C and
1180˚C, observed that the permittivity increases gradu-
ally with the increase in the composition of x and takes a
maximum of 290,15 for the sample with Ti = 42% in-
cluded in the morphotropic phase boundary (MPB) at the
temperature 1180˚C. This maximum of dielectric activity
can be explained by the presence of several directions of
spontaneous polarization relating to the existence of the
two structures rhombohedral and tetragonal. Sample No.
4 (20/39/41) at the sintering temperature of 1180˚C has
an exception in the evolution of εr (T). The dielectric
constant increases continuously as a function of tem-
perature, so this sample does not have a Curie tempera-
ture to a temperature between (0, 450˚C) [18,19].
4. Conclusion
The compounds of the solution solid zirconate-titanate
lead, noted PZT, general formula (0.80 − x)Pb
(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 as x varies from
0.30 to 0.42 by setup of 0.03, and it has been prepared
from a mixture of oxides by the method ceramics. The
Figure 5. Dielectric constant (ε) according to the variation
of x (Ti) in the composition and temperature.
Open Access MSA

Synthesis and Dielectric Properties of (0.80 − x)Pb(Cr1/5,Ni1/5,Sb3/5)O3-xPbTiO3-0.20PbZrO3 Ferroelectric Ceramics
Open Access MSA
750
effect of sintering temperature on density and porosity
was studied to achieve the optimum sintering tempera-
ture corresponding to the maximum density and mini-
mum value of porosity, because this temperature (1180˚C)
corresponds to a better quality product. The parameters
of the lattice: aT and cT of the tetragonal structure and aR
of the rhombohedral structure were found to change
when composition is modified. The
0.20PbZrO3-0.42PbTiO3-0.38Pb(Cr1/5,Ni1/5,Sb3/5)O3 cera-
mics sintered at 1180˚C exhibit good Dielectric proper-
ties at the new MPB εr = 4262.48, and Tc = 340˚C.
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