Perovskite phase formation and ferroelectric properties of the
lead nickel niobate–lead zinc niobate–lead zirconate titanate
ternary system
Naratip Vittayakorn, Gobwute Rujijanagul, and Tawee Tunkasiri
Department of Physics, Faculty of Science, Chiang Mai University, Chiang Mai 50200 Thailand
Xiaoli Tan and David P. Cann
Materials Science and Engineering Department, Iowa State University, Ames, Iowa 50011
(Received 23 June 2003; accepted 24 September 2003)
The ternary system of lead nickel niobate Pb(Ni
1/3
Nb
2/3
)O
3
(PNN), lead zinc niobate
Pb(Zn
1/3
Nb
2/3
)O
3
(PZN), and lead zirconate titanate Pb(Zr
1/2
Ti
1/2
)O
3
(PZT) was
investigated to determine the influence of different solid state processing conditions on
dielectric and ferroelectric properties. The ceramic materials were characterized using
x-ray diffraction, dielectric measurements, and hysteresis measurements. To stabilize
the perovskite phase, the columbite route was utilized with a double crucible technique
and excess PbO. The phase-pure perovskite phase of PNN–PZN–PZT ceramics was
obtained over a wide compositional range. It was observed that for the ternary system
0.5PNN–(0.5 - x)PZN–xPZT, the change in the transition temperature (T
m
) is
approximately linear with respect to the PZT content in the range x 0 to 0.5. With
an increase in x, T
m
shifts up to high temperatures. Examination of the remanent
polarization (P
r
) revealed a significant increase with increasing x. In addition, the
relative permittivity (
r
) increased as a function of x. The highest permittivities
(
r
22,000) and the highest remanent polarization (P
r
25 C/cm
2
) were recorded
for the binary composition 0.5Pb(Ni
1/3
Nb
2/3
)O
3
–0.5Pb(Zr
1/2
Ti
1/2
)O
3
.
I. INTRODUCTION
Lead-based complex perovskites, such as Pb(Zn
1/3
Nb
2/3
)O
3
(PZN) and Pb(Ni
1/3
Nb
2/3
)O
3
(PNN), having the general
formula Pb(B'B)O
3
have received significant attention
since the 1970s because of their peculiar dielectric and
piezoelectric behavior. These materials have been ap-
plied in many areas such as electrostrictive actuators,
transducers, and multilayer ceramic capacitors.
1–6
Lead zinc niobate, PZN, was first synthesized in the
1960s.
7
Its permittivity versus temperature curve dis-
played a broad peak around 140 °C (T
m
) with a strong
frequency dependence. Extremely high relative permit-
tivities have been measured in the vicinity of the peak
with a
r
∼ 60,000 reported for single crystals.
4,8–11
Nanometer-level chemical heterogeneity in the form of
short range order of Zn
2+
and Nb
5+
at B-sites was pro-
posed to account for the observed diffuse phase transi-
tion.
12,13
The crystal structure of PZN is rhombohedral
(3m) at room temperature and transforms to cubic
(Pm3m) at high temperatures.
Unfortunately, phase-pure perovskite PZN polycrys-
talline ceramics have not been synthesized by conven-
tional solid-reaction methods because of a steric and an
electrostatic interaction between high polarization of the
Pb
2+
cation and the Zn
2+
cation, which favors the for-
mation of the pyrochlore phase instead of the perovskite
phase.
14
Moreover, the low tolerance factor and small
electronegativity difference
2
makes the perovskite phase
unstable, requiring the addition of normal ferroelectric
compounds such as BaTiO
3
15
and PbTiO
3
16
to stabilize
the perovskite phase. Recently, Fan et al.
17,18
mixed
Pb(Zr
0.47
Ti
0.53
)O
3
with PZN by a conventional solid-
state reaction method and successfully stabilized perov-
skite PZN. A morphotropic phase boundary (MPB)
between the PZN-rich rhombohedral phase and the PZT-rich
tetragonal phase was reported at PZN:PZT47/53 1:1.
At this composition, a high electromechanical coupling
factor of k
p
0.67 was measured.
Lead nickel niobate (PNN) exhibits a diffuse phase
transition around -120 °C with a much lower peak per-
mittivity of about 4000.
19
The crystal structure of PNN at
room temperature is cubic (Pm3m) with a lattice param-
eter of 4.03 Å.
19
Phase-pure perovskite PNN can be
prepared via the columbite method.
2,20
Luff et al.
21
investigated solid solutions in the PNN–PbTiO
3
–PbZrO
3
system and identified the composition of 0.5PNN–
0.35PT–0.15PZ with optimal piezoelectric properties.
Detailed reaction kinetics during solid state processing of
J. Mater. Res., Vol. 18, No. 12, Dec 2003 © 2003 Materials Research Society 2882
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Copyright by Chiang Mai University
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Copyright by Chiang Mai University
All rights reserved