Phase formation and dielectric phase transition in Ba1-xCaxTi0.6Zr0.4O3 solid solutions

Article abstract of DOI:10.1016/j.jpcs.2006.03.003

Perovskite types Ba_1-xCa_xTi_0.6Zr_0.4O₃ (with x=0.0-0.5) ceramics have been prepared through solid state reaction route. The room temperature XRD study suggests the compositions with x=0.0 and x=0.1 have single phase cubic symmetry. With further increase in Ca content, solid solution breaks and an orthorhombic CaTiO₃ like phase is developed. The dielectric study on single phase compositions (x=0.0 and 0.1) reveals that the materials are of relaxor type and undergo a diffuse type ferroelectric phase transition. In the Ca containing composition higher transition temperature is observed than the pure BaTi_0.6Zr_0.4O₃ materials. In the paraelectric region (above T_c) lower diffusivity is observed in the Ca containing composition. The strength of relaxation is calculated and found to be more in Ca containing material than that of pure BaTi_0.6Zr_0.4O₃ composition.

Full text of DOI:10.1016/j.jpcs.2006.03.003

ARTICLE IN PRESS
Journal of Physics and Chemistry of Solids 67 (2006) 2257–2262
www.elsevier.com/locate/jpcs
Phase formation and dielectric phase transition in Ba1ꢀxCaxTi0.6Zr0.4O3
solid solutions
Ã
S.K. Routa, , E. Sinhaa, S. Panigrahia, J. Berab, T.P. Sinhac
aDepartment of Physics, National Institute of Technology, Rourkela-769 008, Orissa, India
bDepartment of Ceramic Engineering, National Institute of Technology, Rourkela-769 008, Orissa, India
cDepartment of Physics, Bose Institute, 93/1 A.P.C. Road, Kolkata, India
Received 1 February 2006; received in revised form 26 February 2006; accepted 8 March 2006
Abstract
Perovskite types Ba1ꢀxCaxTi0.6Zr0.4O3 (with x ¼ 0.0–0.5) ceramics have been prepared through solid state reaction route. The room
temperature XRD study suggests the compositions with x ¼ 0.0 and x ¼ 0.1 have single phase cubic symmetry. With further increase in
Ca content, solid solution breaks and an orthorhombic CaTiO3 like phase is developed. The dielectric study on single phase compositions
(x ¼ 0.0 and 0.1) reveals that the materials are of relaxor type and undergo a diffuse type ferroelectric phase transition. In the Ca
containing composition higher transition temperature is observed than the pure BaTi0.6Zr0.4O3 materials. In the paraelectric region
(above Tc) lower diffusivity is observed in the Ca containing composition. The strength of relaxation is calculated and found to be more
in Ca containing material than that of pure BaTi0.6Zr0.4O3 composition.
r 2006 Published by Elsevier Ltd.
Keywords: D. Dielectrics
1. Introduction
research. It is accepted that the relaxor nature is related to
the micropolar regions induced by B-site substitution, and
the atomic radii and chemical valence differences of ions
will often affect the relaxor effect. Most relaxor ferro-
electrics belong to family of complex lead-based perovskite
oxides, such as Pb(Mg1/3Nb2/3)O3 (PMN), which is often
considered as a model system. However, these compounds
have the obvious disadvantages associated with the
volatility and toxicity of PbO. Lead-free relaxor materials
present great interest both for applications in field of
environmental protection and for fundamental studies.
Recently, relaxor behavior has been found in many lead-
free materials, such as, KNbO3–BaTiO3 [7], KNbO3–Ba-
TiO3–CaTiO3 [9] and BaTiO3–BaZrO3–BaLiF3 [10].
In BaTiO3–BaZrO3 system, it has been reported [11] that
at ꢁ15 atom% Zr substitution, the three transition
temperatures of BaTiO3, rhombohedra to orthorhombic,
orthorhombic to tetragonal and tetragonal to cubic, merge
near room temperature and the doped material exhibits
enhanced dielectric constant. With further increase in Zr
contents beyond 15 atom%, a diffuse dielectric anomaly in
ceramic has been observed with the decrease in the
Recently a new wave of interest has risen on relaxor
ferroelectrics with complex perovskite structure due to its
wide use in fabrication of multilayer ceramic capacitors,
electrostrictive actuators, and electromechanical transdu-
cers. The ferroelectric-relaxor behavior, which is character-
ized by diffuse phase transition, has been studied
extensively both theoretically as well as experimentally
since a long time [1–9]. Various physical models have been
proposed to explain the properties of relaxor behavior, e.g.,
microscopic composition fluctuation [2], order–disorder
transition [3], microdomain and macrodomain switching
[4], ‘dipolar-glass’ model [5], and quenched random field
model [6]. Despite of continuous fundamental investiga-
tions on relaxor ferroelectrics in recent years, the nature of
their extraordinary properties has not yet been understood
completely, and they are still the subject of intensive
Ã
Corresponding author. Tel.: +91 94370 85441.
E-mail addresses: skrout@nitrkl.ac.in, skrout1234@rediffmail.com
(S.K. Rout).
0022-3697/$ - see front matter r 2006 Published by Elsevier Ltd.
doi:10.1016/j.jpcs.2006.03.003

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2258
transition temperature [12] and the material showed typical
relaxor–like behavior in the range 25–42 atom % Zr
substitution [13]. Unfortunately, these lead-free materials
show their relaxor properties at relatively low temperature
(o250 K). In the present study an attempt has been made
to shift the TC of BaTi0.6Zr0.4O3 (BTZ) relaxor composi-
tion towards room temperature.
CT
CT
Mixed Phase
x=0.5
x=0.4
x=0.2
Mixed Phase
Mixed Phase
2. Experimental
x=0.1
x=0.0
Cubic
Cubic
[011]
The samples were prepared through solid state reaction
route. The compositions with different values of x ( ¼ 0.0,
0.1, 0.2, 0.4 and 0.5) in Ba1ꢀxCaxTi0.6Zr0.4O3 were
prepared from BaCO3 (S.D. Fine Chem., Mumbai),
CaCO3 (S.D. Fine Chem., Mumbai), TiO2 (E. Merck India
Ltd.) and ZrO2 (Loba Chem., Mumbai). All the chemicals
were more than 99% pure. The raw powders were
thoroughly mixed in agate mortar using IPA. The
homogeneous mixtures were calcined successively at:
1300 1C for 4 h; 1350 1C for 4 h; and finally 1400 1C for
6 h with intermediate mixing and grinding. The synthesized
powders were characterized with respect to phase identi-
fication and lattice parameter measurements, using Cu-Ka
XRD (PW-1830, Philips, Netherlands). The structural
refinements were carried out using Rietveld refinement
program MAUD [14] and as reported elsewhere [15]. For
electrical property measurement of the single phase
compositions, the disks were pressed uniaxially at
200 MPa with 2 wt% PVA solution added as binder and
that were sintered at 1400 1C for 6 h. The diameter and
thickness of the sintered disks were measured and found to
be 12 and 2 mm respectively. Disk densities were evaluated
using Archimedes principle and found to be ꢁ97% of their
theoretical density. The average grain sizes were measured
through optical microscope connected with a PC and
found to be 22.7 and 5.8 mm for the composition with
x ¼ 0.0 and x ¼ 0.1 respectively. Silver electrodes were
printed on to opposite disk faces and were sintered at
700 1C for 15 min. Dielectric measurements were carried
out over range 10 Hz to 5 MHz using HP-4192A LF
impedance analyzer, connected with a PC. The temperature
was controlled with a self-designed programmable oven.
All the dielectric data were collected at an interval of 3 1C,
while heating at a rate of 0.5 1C minꢀ1. The results were
found to be reproducible.
[200]
[112]
[111]
40
20
30
50
60
70
°2θ
Fig. 1. XRD pattern of (Ba1ꢀXCaX) Ti0.6Zr0.4O3 ceramics with different
Ca (x) contents.
1600
1400
1200
1000
1 kHz
10 kHz
100kHz
1 MHz
800
200
(a)
(b)
150
100
50
0
120
160
200
240
280
320
Temperature (K)
Fig. 2. Temperature dependency of permittivity of BaTi0.6Zr0.4O3 at
various frequencies: (a) real part; (b) imaginary part.
orthorhombic CaTiO3 (CT) like phase is observed along
with tetragonal Ba0.9Ca0.2Ti0.6Zr0.4O3 phases. Recently,
Levin et al. [16] reported that solubility of CaO in BaZrO3
increases from few percent at 1400 1C to about 30% at
1650 1C. But in the present study at 1400 1C/6 h the
solubility of Ca, in Ba (Ti0.6Zr0.4) O3 fails at around
20 atom%. The Zr4+ ion is chemically more stable than
Ti4+ ion [17] may be the one cause for breaking of solid
solution at the studied temperature. The detailed structural
parameters and quantities of the phases present in the Ca-
rich compositions were studied [15] using Rietveld refine-
ment technique.
Figs. 2 and 3 show the temperature dependency of the
permittivity and dielectric loss of bulk BaTi0.6Zr0.4O3 and
Ba0.9Ca0.1Ti0.6Zr0.4O3 single phase compositions at differ-
ent frequencies. The figures show, the value of e0 increases
gradually to a maximum value (em) with increase in
temperature up to the transition temperature and then
decreases smoothly indicating a phase transition. The maxi-
mum of dielectric permittivity, em and the corresponding
3. Results and discussion
Fig. 1 shows the room temperature XRD pattern of the
Ba1ꢀxCaxTi0.6Zr0.4O3 samples with different Ca (x) con-
centrations. The compositions, x ¼ 0.0 and x ¼ 0.1, i.e.,
Ba(Ti0.6Zr0.4)O3 and Ba0.9Ca0.1Ti0.6Zr0.4O3 were indexed in
cubic symmetry with space group pm3 m. It can be noticed
from the figure that peaks are shifting towards higher angle
indicating decrease in lattice parameters in the single phase
compositions. In the compositions with higher Ca content,
these peaks were shifting towards lower angle and an

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2259
700
600
500
400
the transition temperature (Tm) which is caused by
inhomogeneous distribution of the Zr ion on Ti site and
mechanical stress in the grain [21]. It can be also noticed
from the figures, that higher transition temperatures (Tms)
are observed in the Ca containing composition than the
pure BTZ. When Ca is substituted in 12 coordination sites,
it traps eight near neighbors Oxygen and four more distant
ones. That modification assumes a possible displacement of
Ca2+ out of the oxygen dodecahedron center to induce a
dipolar moment whose occurrence may lead to increase in
transition temperature. The diffuse nature of the transition
in the case of ferroelectric ceramics is usually attributed to
a distribution of grain sizes and/or to a gradient of
quadraticity which leads to a distribution of transition
temperature. This is more pronounced in samples contain-
ing both Ti and Zr may be due to the difference in ionic
radius. Here additional spatial fluctuations in the mixture
of Ti and Zr ions lead to the coexistence of regions of
different Curie temperatures depending up on their
concentration [22] in the solid solution. It is reported
[23], as the grain size decreases, the maximum dielectric
constant and transition temperature decreases. The effect
of grain size originates from the higher surface tension in
smaller grains [24], which acts in the same manner as
hydrostatic pressure thus decreasing the Curie point [25].
In addition, the force experienced by the atoms and ions in
the vicinity of, or far from, the surface of grain are not
similar. These considerations suggest that a quadraticity
gradient may exist between the surface and the bulk of
grains [26]. For smaller grain sizes, however, the superficial
layers of the grains represent a significant fraction and may
dominate the structural and the dielectric measurement
[22].
1 kHz
10kHz
100 kHz
1 MHz
(a)
(b)
100
50
0
140 160 180 200 220 240 260 280 300 320
Temperature (K)
Fig. 3. Temperature dependency of permittivity of Ba0.9Ca0.1Ti0.6Zr0.4O3
at various frequencies: (a) real part; (b) imaginary part.
temperature maximum Tm, depend upon the measurement
frequency for all the compositions. The magnitude of
dielectric constant decreases with increase in frequency and
the maximum shifts to higher temperature. This indicates
that the dielectric polarization is of relaxation type in
nature such as dipolar glasses. In analogy with spin glasses,
such a behavior of the dynamic susceptibility in disordered
ferroelectric is supposed to be concerned with the existence
of the broad spectrum of relaxation times. It is generally
considered that the Debye model is based on the
assumption of a single relaxation time. The model fails
because of the existence of a distribution of relaxation
times. Such a distribution of relaxation time implies that
the local environment seen by individual dipoles differs
from site to site. As shown in the figures, the dielectric loss
values of the ferroelectric phase were reduced substantially
in the paraelectric phase (above Tm). The observed lower
temperature (below Tm) frequency dispersion may also
have some contribution from the space charge effect. The
high value of dielectric loss at 1 kHz is due to the presence
of all types of polarizations including space charge effect. A
gradual decrease of space charge is observed at higher
frequency. An increase in the values of ꢀ00 at lower
temperature region may also be due to the presence of
space charge polarization and those were reduced sub-
stantially at temperatures near paraelectric phase. The
space charge effects are more prominent in the both low
frequency and low temperature regions [18].
A diffuse phase transition is generally characterized by
(a) broadening of dielectric constant versus temperature
curve (b) a relatively large separation (in temperature)
between the maximum of the real (dielectric constant) and
imaginary (dielectric loss) part of the dielectric spectrum (c)
a deviation from Curie–Weiss law in the vicinity of Tm; (d)
frequency dispersion of both e0 and tan d (dielectric loss) in
transition region thereby implying a frequency dependency
of Tm.
It is known that the dielectric permittivity of a normal
ferroelectric above the Curie temperature follows the
Curie–Weiss law described by
ꢀ0 ¼ C=ðT ꢀ T0Þ; ðT4TCÞ,
As a rule [11] this relaxation occurs in disorder ionic
structures, particularly in solid solution. Within the curie
range of temperature, dielectric permittivity achieves very
high value and displays very large dispersion, which is
reminiscent of that found for orientational glasses [19]. The
two cations Ti4+and Zr4+ in the B sites are all
ferroelectrically active, so these cations are off-centered in
the octahedral site and give rise to a local dipolar moment
[20]. Qualitatively, the strongly broadened dielectric peak
indicates that the phase transition is of a diffuse type near
where T0 is the Curie–Weiss temperature and C is the
Curie–Weiss constant. Fig. 4 shows the plot of inverse
dielectric constant versus temperature at different frequen-
cies of two different single phase compositions in the
system Ba1ꢀxCaxTi0.6Zr0.4O3 ; (a) x ¼ 0.0, (b) x ¼ 0.1. A
clear deviation from Curie–Weiss law can be seen in all
representative frequency. The parameters obtained at
1 kHz and 1 MHz are listed in Table 1. The parameter
DTm, which describes the degree of the deviation from the

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1.50
1.25
1.00
0.75
0.50
-7
0
γ=1.85
γ=1.80
-8
-9
-1
-2
-3
-4
-5
-6
(a)
100 kHz
1 kHz
-10
-11
-12
10 kHz
100 kHz
1 MHz
2.5
2.0
1.5
x=0.0
x=0.1
(b)
320
1
2
3
4
5
160
200
240
280
ln (T-Tm)(K)
Temperature (K)
Fig. 5. Log (1/e0–1/em) vs log (T–Tm) for Ba1ꢀxCaxTi0.6Zr0.4O3 at
100 kHz.
Fig. 4. Temperature dependency of 1/e0 for Ba1ꢀxCaxTi0.6Zr0.4O3 at
various frequencies: (a) x ¼ 0.0 and (b) x ¼ 0.1.
The slopes of the fitting curve are used to determine the
parameter g value. The values of g at 100 kHz are found to
be 1.85 and 1.8 for x ¼ 0.0 and x ¼ 0.1 compositions,
respectively, indicating transitions are of diffuse type. The
values of the g show that the materials are highly
disordered. The decreased value of g with Ca content
indicates the decrease in diffusivity. The broadened di-
electric maximum (in e0 vs temperature curve) and its
deviation from Curie–Weiss law are the main character-
istics of a diffuse phase transition of the material. The
diffuse phase transition and deviation from Curie–Weiss
type may be assumed due to disordering. The broadness in
e0 vs temperature curve is one of the most important
characteristics of the disordered perovskite structure with
diffuse phase transition. The broadness or diffusiveness
occurs mainly due to compositional fluctuation and
structural disordering in the arrangement of cation in one
or more crystallographic sites of the structure. This
suggests a microscopic heterogeneity in the compound
with different local Curie points. The nature of the
variation of dielectric constant and non polar space group
suggests that the material may have ferroelectric phase
transition.
Table 1
Parameters obtained from temperature dependency dielectric study on the
composition Ba1ꢀxCaxTi0.6Zr0.4O3 at 1 kHz and 1 MHz
X ¼ 0.0
X ¼ 0.1
1 kHz
1 MHz
1 kHz
1 MHz
Tm(K)
To(K)
C(105K)
DTm
163.5
189.41
1.67
192.713
211.60
1.665
167.47
186.6
1.45
198.79
214
1.42
88.81
251.3
1598.7
74.89
267.6
1370.4
79.64
247.11
657.44
68.73
267.52
572.21
Tcw
em
Curie–Weiss law, is defined as
DTm ¼ TCW ꢀ Tm.
where Tcw denotes the temperature from which the
permittivity starts to deviate from the Curie–Weiss law
and Tm represents the temperature of the dielectric
maximum. The Curie temperature determined from the
graph by extrapolation of the reciprocal of dielectric
constant of the paraelectric region and the value obtained
at 1 kHz and 1 MHz are given in Table 1.
A modified Curie–Weiss law has been proposed by many
research groups to describe the diffuseness of a phase
transition as
The plot of log (n) vs 1/Tm is shown in Fig. 6 for two
different compositions. The nonlinear nature indicates that
the data cannot be fitted with a simple Debye equation.
The Debye medium is a classic dielectric. Its dielectric
constant is described by the Debye equation;
1
1
g
ꢀ
¼ ðT ꢀ TmÞ =C0,
ꢀ0 ꢀm
ꢀ ¼ ꢀ1 þ Dꢀ=ð1 þ o2t2Þ,
Where g and C’ are assumed to be constant. The parameter
g gives information on the character of the phase
transition; for g ¼ 1, a normal Curie–Weiss law is
obtained, for g ¼ 2, it reduces to the quadratic dependency
which describes a complete diffuse phase transition. The
plot of log (1/e0ꢀ1/em) vs log (T–Tm) at 100 kHz for two
different compositions is shown in Fig. 5. Linear relation-
ships are observed.
where t is the dielectric relaxation time of the dipole
polarization, De, the contribution of the dipole polarization
to the static dielectric constant and eN is the high
frequency dielectric constant, which remains nearly con-
stant with the change of temperature.
In Debye medium, the dipoles (or molecules) are free to
rotate and are thermally activated; the dipole moments of
dipoles have the same value, and there is no interaction

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6.2
6.0
5.8
5.6
5.4
5.2
energy and pre-exponential factor are both consistent with
thermally activated polarization fluctuations.
The empirical relaxation strength describing the fre-
quency dispersion of Tm is defined as
6.0
5.8
5.6
5.4
5.2
5.0
x=0.0
DTres ¼ Tmð1 MHzÞ ꢀ Tmð10 kHzÞ
,
where DTres was derived from the dielectric measurement
of the ceramics. The values of DTres are found to be 20.14,
and 25.44 for the compositions with x ¼ 0.0 and x ¼ 0.1,
respectively. The relaxor behavior as observed in this
ceramics can be induced by many reasons such as
microscopic compositions fluctuation, the merging of
micropolar regions in to macropolar regions, or a coupling
of order parameter and local disorder mode through the
local strain [28–30]. Vugmeister and Glinichuk reported
that the randomly distributed electrical field of strain field
in a mixed oxide system was the main reason leading to the
relaxor behavior [31].
x=0.1
15
6
7
8
9
10
ln ν
11 12 13 14
Fig. 6. 1/Tm as function of the measured frequency of Ba1ꢀxCaxTi0.6
Zr0.4O3. The symbols are the experimental data points and the line is
corresponding fitting to the Vogel–Fulcher relationship.
In the studied compositions of solid solutions Ba1ꢀx
CaxTi0.6Zr0.4O3, Ba and Ca ions occupy the A sites of the
ABO3 perovskite structure and Zr and Ti ions occupy the B
site. As previously mentioned both Ti and Zr are
ferroelectrically active and these cations are off-centered
in the octahedral site, giving rise to a local dipolar moment
[20]. In perovskite-type compounds, the relaxor behavior
appears when at least two cations occupy the same
between the dipoles. This means that the dipoles can be
frozen only at temperature 0 K, and thus, t is dependent on
the temperature according to
ꢀ
ꢁ
t ¼ n0 exp T0=T ,
where n0 is the attempt frequency of the molecules (or the
Debye frequency) and T0 is the equivalent temperature of
activation energy.
crystallographic site A or B. The ionic radius of Zr4+
4+
˚
˚
(0.98 A) is larger than that of Ti (0.72 A). Therefore an
inhomogeneous distribution results at the B site of the
structure. A cationic disorder induced by B-site substitu-
tion is always regarded as the main derivation of relaxor
behavior. However, according to our present results, it
implies that the observed higher relaxation strength should
attribute to a cationic disorder induced by both A-site and
B-site substitutions. The different effects of A-site sub-
stitution on cation ordering and the stability of the polar
region are considered to be based on the polarizability of
cations and the tolerance factor of the perovskite structure.
For perovskites with the general formula of ABO3, the
following equation can be used to calculate the tolerance
factor (t) [20]:
In any material system, it is impossible that all the
dielectrics are free, so the dipoles in the Debye model are
nonrealistic. The more realistic dipole is not free as in glass
which is another classic dielectric. The dipoles in the glass
do interact with their neighbors. The interaction makes the
dipole freeze into a configuration devoid of long-range
order at Tf. That is, the effect of Tf in glass is same as that
of 0 K in Debye medium. Therefore, the relaxation time in
a glass can be expressed by Vogel–Fulcher law [27,28].
In order to analyze the relaxation features, i.e., relation
between n and Tm of the ceramics, the experimental curves
were fitted using the Vogel–Fulcher formula [27,28].
ꢂ
ꢃ
ꢀEa
n ¼ n0 exp
,
kBðTm ꢀ Tf Þ
ðRA þ ROÞ
pffiffi
t ¼
,
Where n0 is the attempt frequency, Ea is the measure of
average activation energy, and kB is the Boltzman constant,
and Tf is the freezing temperature. Tf is regarded as the
temperature where the dynamic reorientation of the dipolar
cluster polarization can no longer be thermally activated.
The fitting curves are shown in Fig. 6. The fitting
parameters for different compositions are; for x ¼ 0.0,
Ea ¼ 0.1020 eV, Tf ¼ 106 K, n0 ¼ 8.5 ꢂ 1011 Hz; for x ¼
0.1, Ea ¼ 0.0461 eV, Tf ¼ 130 K, and n0 ¼ 2.51 ꢂ 109 Hz.
The close agreement of the data with the V–F relationship
suggests that the relaxor behaviors in the systems are
analogous to that of a dipolar glass with polarization
fluctuations above a static freezing temperature. The
observed difference in average activation energy may be
due to the large difference in grain size. The activation
2ðRB þ ROÞ
where RA is the radius of A, RB is the radius of B, and RO is
the radius of O. As the t increases, the normal ferroelectric
phase becomes stabilized. So Ba2+ cations can stabilize the
normal ferroelectrics due to the larger ionic diameter and
the higher polarizability. While Ca2+ cations in A sites
behave as a typical destabilizer against normal ferro-
electrics and induce paraelectric behavior due to smaller
ionic diameter and lower polarization. In this case, more
macrodomains (long-range ordered regions) in Ca sub-
stituted ceramics will breakup into micropolar regions than
that in pure BTZ ceramics. Mechanical stress in the grain,
is the cause of the relaxor behavior in the Ti and Zr mixed
composition [28–30]. Stresses were introduced into the

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2262
lattice during cooling after sintering process, which is due
to the transition from a cubic to rhombohedral phase
below the Curie temperature [32]. On the other hand, it is
known that BaZrO3 shows nonferroelectric (cubic para-
electric phase) behavior at all temperatures because, the Zr
ion locates at the central equilibrium position of the
BaZrO3 lattice. In this case the macrodomain in BaTiO3
could be divided into the microdomains which probably
cause the relaxor behavior.
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4. Conclusion
[15] S.K. Rout, Phase formation and dielectric study on BaO–TiO2–ZrO2
perovskite system Ph.D Thesis, Department of Physics, NIT,
Rourkela, 2006.
Perovskite type Ba1ꢀxCaxTi0.6Zr0.4O3 (with x ¼ 0.0, 0.1,
0.2, 0.4 and 0.5) ceramics have been prepared through solid
state reaction route. The room temperature XRD study
suggests that the compositions with x ¼ 0.0 and 0.1 have
single phase cubic symmetry with space group Pm3 m.
With further increase in Ca content the solid solution
breaks at the experimental temperature. An orthorhombic
CaTiO3 like phase is observed along with tetragonal
Ba0.8Ca0.2Ti0.6Zr0.4O3 phase. The dielectric study on single
phase compositions reveals that the materials are of relaxor
type and undergo a diffuse type ferroelectric phase
transition. An improvement of transition temperature is
observed in the Ca containing composition. Lower
diffusivity and higher strength of relaxation is observed
in the Ca containing compositions as compared to the pure
BaTi0.6Zr0.4O3 materials.
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