Ferroelectric Lead Titanate (PbTiO3 or PT)
• Ferroelectric with similar structure to BaTiO3
• Phase transition from Paraelectric Cubic to
Ferroelectric Tetragonal phases
• High Curie Point (~ 490 C)
• Suitable
for
high-frequency
and
hightemperature applications, as a result of high Curie
Point, low dielectric constant (er ~ 200), and large
electromechanical anisotropy (kt/kp > 10)
• An important end member of widely used PZT
(xPbTiO3-(1-x)PbZrO3)
• Difficult to obtain a dense sintered body due
to large volume change upon cooling ( as a
result of large c/a = 1.063 (strain > 6%))
• Modified compositions with various dopant (
Lattice constants versus temperature
for PbTiO3
alkaline or rare earth elements, such as Ca, Sr, and
Ba, and other dopants such as Sn, W, Bi, and Y to
obtain a crack free ceramic and to improve
properties
(Ferroelectric?) Lead Zirconate (PbZrO3 or PZ)
Lattice constants versus temperature
(in pseudo-tetragonal) for PbZrO3
Dielectric constant versus
temperature for PbZrO3 ceramic
 Above 230 C, the structure is cubic-perovskite (similar to BaTiO3) 
 Dielectric constant shows “anomaly” at 230 C (reaches high peak) 
 Above 230 C, dielectric constant follows Curie-Weiss relation 
Ferroelectric Material ?
 No ferroelectric hysteresis below “transition temperature” 230 C 
 Volume contraction upon cooling (c/a < 1) 
 Orthorhombic Structure 
Anti-Ferroelectric Material 
Antiferroelectricity
Antiferroelectricity
Anti-ferroelectric materials  Non-polar, Nonferroelectric materials that revert to a ferroelectric state
when subjected to sufficiently high electric field, causing
a “double-loop hysteresis”
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
PZT (xPbZrO3 – (1-x)PbTiO3)

 Binary Solid Solution 
PbZrO3 (antiferroelectric matrial with orthorhombic structure)
and
PbTiO3 (ferroelectric material with tetragonal perovskite structure)

Perovskite Structure (ABO3) with Ti4+ and Zr4+ ions “randomly”
occupying the B-sites

Important Transducer Material (Replacing BaTiO3)
• Higher electromechanical coupling coefficient than BaTiO3
• Higher Tc results in higher operating and fabricating temperatures
• Easily poled
• Wider range of dielectric constants
• relatively easy to sinter at lower temperature than BaTiO3
• form solid-solution compositions with several additives which
results in a wide range of tailored properties
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
PZT Solid Solution Phase Diagram
Zr/Ti ratio 52/48 MPB
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
PZT Solid Solution Phase Diagram
Zr/Ti ratio 52/48 MPB showing structure changes
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Abrupt
changes
in
lattice
constants at room temperature for
PZT system lead to anomalous
behaviors in dielectric and
piezoelectric properties
Variation of polarization with PZ
contents indicates that the highest
polarization
is
in
the
rhombohedral structure that does
not have highest er and d
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Composition
dependence
of
dielectric
constant
(K)
and
electromechanical planar coupling
coefficient (kp) in PZT system

This shows enhanced dielectric and
electromechanical properties at the
MPB

Increased interest in PZT materials
with
MPB-compositions
for
applications
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Electromechanical coupling coefficients
Piezoelectric d constants
Variation of room temperature piezoelectric properties with PZT compositions
Note: highest values on tetragonal side of the composition
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Piezoelectric g strain coefficients
Dielectric constants
Variation of room temperature piezoelectric properties with PZT compositions
Note: highest dielectric constants on tetragonal side of the composition
BUT high piezoelectric g strain coefficients into rhombohedral side
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Possible domain states
Value of the mixed phase region at the MPB in poling of PZT
vs other perovskite ferroelectrics
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Advantages of PZT Solid-Solution System
• Above Curie Point (or Curie Temperature), the symmetry is cubic
with perovskite structure
• High Tc across the diagram leads to more stable ferroelectric states
over wide temperature ranges
• There is a two-phase region near the Morphotropic Phase
Boundary (MPB) (52/48 Zr/Ti composition) separating
rhombohedral (with 8 domain states) and tetragonal (with 6
domain states) phases
• In the two-phase region, the poling may draw upon 14 orientation
states leading to exceptional polability
• Near vertical MPB results in property enhancement over wider
temperature range for chosen compositions near the MPB
Compositions and Modifications of PZT System
1. Effects of composition and grain size on properties
MPB compositions
(Zr/Ti = 52/48)

Maximum dielectric and
piezoelectric properties

Selection of Zr/Ti can be used
to tailor specific properties

High kp and er are desired
 Near MPB compositions
OR
High Qm and low er are desired
 Compositions away from
MPB
Grain Size
(composition and processing)

Fine-Grain ~ 1 mm or less
Coase-Grain ~ 6-7 mm

Some oxides are grain growth
inhibitor (i.e. Fe2O3)

Some oxides are grain growth
promoter (i.e. CeO2)

Dielectric and piezoelectric
properties are grain-size
dependent
Compositions and Modifications of PZT System
Dependence of dielectric and piezoelectric properties on average
grain size in the ceramic Pb(Zr0.51Ti0.49)O3 + 0.1 wt% MnO2 at a
constant density of 7.70-7.85 g/cm3

Piezoelectric properties increase linearly with increasing grain size
Compositions and Modifications of PZT System
2. Modification by element substitution
Element substitution  cations in perovskite lattice (Pb2+, Ti4+, and Zr4+)
are replaced partially by other cations with the same chemical valence
and similar ionic radii and solid solution is formed
 Pb2+ substituted by alkali-earth metals, Mg2+, Ca2+, Sr2+, and Ba2+ 

PZT replaced partially by Ca2+or Sr2+
Tc  BUT kp, e33 , and d31  
Shift of MPB towards the Zr-rich side 
 Density  due to fluxing effect of Ca or Sr ions 
Ti4+ and Zr4+ substituted by Sn4+ and Hf4+ , respectively 

Ti4+ replaced partially by Sn4+
c/a ratio decreases with increasing Sn4+ content 
 Tc  and  stability of kp and e33 
Compositions and Modifications of PZT System
3. Influences of low level “off-valent” additives (0-5 mol%)
on dielectric and piezoelectric properties
Two main groups of additives:
1. electron acceptors (charge on the replacing cation is smaller)
(A-Site:K+, Rb+ ; B-Site: Co3+, Fe3+, Sc3+, Ga3+, Cr3+, Mn3+, Mn2+, Mg2+, Cu2+)
(Oxygen Vacancies)


Reduce both dielectric and piezoelectric responses
Increase highly asymmetric hysteresis and larger coercivity

Much larger mechanical Q
“Hard PZT”
2. electron donors (charge on the replacing cation is larger)
(A-Site: La3+, Bi3+, Nd3+; B-Site: Nb5+, Ta5+, Sb5+)
(A-Site Vacancies)

Enhance both dielectric and piezoelectric responses at room temp

Under high field, symmetric unbiased square hysteresis loops

low electrical coercivity
“Soft PZT”
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Dielectric constant vs temperature of various types PZT materials
Modified PZT System
3.1 Hard Doping: Hard PZT

(A-Site:K+, Rb+ ; B-Site: Co3+, Fe3+, Sc3+, Ga3+, Cr3+, Mn3+, Mn2+, Mg2+, Cu2+)

Oxygen Vacancies in either A-sites or B-sites or Both
(Electroneutrality)

Two
replaced by two
ions OR Two Zr4+ (or Ti4+) replaced by two Fe3+ ions

Space charges inhibit domain motion and Insoluble doped ions inhibit grain growth

Pb2+
K+
Increased Qm and Ec, Decreased loss tangent, and Lowered dielectric and
piezoelectric activities

“Hard PZT”

Rugged Applications
(High Temperature and High Driving Loads)
Modified PZT System
3.2 Soft Doping: Soft PZT

(A-Site: La3+, Bi3+, Nd3+; B-Site: Nb5+, Ta5+, Sb5+)

A-Site Vacancies (Electroneutrality)

Two Pb2+ replaced by two La3+ ions OR Two Zr4+ (or Ti4+) replaced by two Nb5+ ions

Easier transfer of atoms leads to increased domain motion at lower electric filed ( Ec)
Internal stress relieve more easily
Increased domain wall mobility

Lowered Qm and Ec, Increased loss tangent, and Increased dielectric and
piezoelectric activities

“Soft PZT”

Applications required higher piezoelectric activities
(Sensors, Actuators, and Transducers)
Modified PZT System
“Hard PZT” Materials
 Curie temperature above 300 C
 NOT easily poled or depoled except at high temperature
 Small piezoelectric d constants
 Good linearity and low hysteresis
 High mechanical Q values
 Withstand high loads and voltages
“Soft PZT” Materials
 Lower Curie temperature
 Readily poled or depoled at room temperature with high field
 Large piezoelectric d constants
 Poor linearity and highly hysteretic
 Large dielectric constants and dissipation factors
 Limited uses at high field and high frequency
Modified PZT System
3.3 Other Doping Ions (Ce, Cr, U, Ag, Ir, Rh, Ni, Mn, Nb, Al)
 Ce-doped PZT  high r, Qm, Qe, e, Ec, kp 
 Cr-doped PZT  high Qm, tan d, with lower kp 
 U-doped PZT  high Qm, r , and tan d 
 Ag, Ir, or Rh-doped PZT  high Qm, kp , and lower e 
 Complexed doping (with two or more metal elements) 

Better than single ion doping (enhances both Qm and kp)
 Compound Dopings (BiFeO3, AgSbO3 or Ca2Fe2O5) 

Reducing dielectric loss at high field
Examples of Practical Modified PZT System
1.
Materials for ceramic filters:
1.1 Range 30-150 MHz (modified PT)
0.99[0.96PbTiO3 + 0.04 La2/3TiO3] + 0.01MnO2
1.2 Range 10-20 MHz
Pb1.03[(Nb2O6)0.07(CrO2)0.03(Zr0.52Ti0.48O3)0.90] + 0.5 wt%MnO2 + 1 wt% La2O3
1.3 Range 1-10 MHz
Pb0.95Sr0.05Mg0.03(Zr0.52Ti0.48)O3 + 0.5 wt%CeO2 + 0.225 wt% MnO2
2.
Materials for underwater ultrasonic transducers:
Pb0.95Sr0.05 (Zr0.54Ti0.46)O3 + 0.9 wt%La2O3 + 0.9 wt% Nb2O5
3.
Materials for high-voltage generator:
[Pb(Nb1/2Sb1/2)O3]0.05 [PbTiO3]0.41 [PbZrO3]0.54
+ 0.2 mol%Nb2O5 + 0.2 mol%Y2O3 + 0.1 wt% MnO2
4.
Materials for electro-acoustic applications:
[Pb(Ni1/3Nb2/3)O3]0.50 [PbTiO3]0.355 [PbZrO3]0.145
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Examples of Commercially Available PZT from APC
Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Examples of Commercially Available PZT from PKI
Navy Type I (PKI-402 and PKI-406)
High power and low losses for driver applications (ultrosonic cleaners, fish finders,
medical applications, and sonars)
Navy Type II (PKI-502)
High electromechanical activity and high dielectric constant for receiver
applications (hydrophones, phono pickups, sound detectors, accelerometers,
delay lines, flow detectors, and flow meters)
Navy Type III (PKI-802 and PKI-804)
High Q and low losses under extreme driving conditions for medical applications
Navy Type V (PKI-532)
High sensitivity, high dielectric constant and low impedance for sensor applications
Navy Type VI (PKI-552 and PKI-556)
High dielectric constant and large displacement for sensor applications
PKI-556 is modified to give higher g33, higher k33, and lower loss factor
La-Doped Lead Zirconate Titanate (PLZT) System
(Pb1-xLax)(Zr1-yTiy)1-x/4VB0.25xO3 and (Pb1-xLax)1-x/2(Zr1-yTiy)VAx/2O3
La3+ into A-sites with B-site-vacancies created and Vacancies created on A-sites
(Charge Balance with combination of both A and B-sites vacancies)

Perovskite Structure (ABO3) similar to BaTiO3 and PZT

Important (First) Transparent Ceramic (Replacing Single Crystals)
(Prepared by Chemical Co-Precipitation and Hot-Press Sintering in Oxygen Atmosphere)
• Increased squareness of the hysteresis loop
• Decreased coercive field and increased dielectric constant
• Maximum coupling coefficients and increased mechanical compliance
• Enhanced optical transparency
As a result of high solubility of

3+
La in

the oxygen octahedral structure
Series of single-phase solid-solution compositions

Less unit-cell distortion and reduced optical anisotropy

Uniform grain-growth and densification
leads to single-phase, pore-free microstructure
La-Doped Lead Zirconate Titanate (PLZT) System
(Pb1-xLax)(Zr1-yTiy)1-x/4VB0.25xO3

( x ~ 2-30 at%)

Notation  x / y / (1-y)

8/65/35  Pb0.92La0.08(Zr0.65Ti0.35)0.98O3
Majority of Research
PLZT 6-9/65/35
In the phase diagram
Phase Diagram of the PZT and PLZT
Solid-Solution Systems

1) La solubility depends on PZ/PT 2)
Excess
La
results
in
reduced
transparency due to mixed phases of
PLZT, La2Zr2O7, and La2Ti2O7 3) La
reduces Tc 4) MPB compositions have
enhanced properties
La-Doped Lead Zirconate Titanate (PLZT) System
MPB
Ferroelectric
tetragonal and
rhombohedral phases
Pyroelectric
Applications
Orthorhombic
Anti-ferroelectric
phases
MPB Compositions
for transducer
applications
Cubic
paraelectric phases
Diffused metastable relaxor
(electrically inducible to
ferroelectric)
for quadratic strain and
electro-optics
Phase Diagram of the PZT and PLZT Solid-Solution Systems
La-Doped Lead Zirconate Titanate (PLZT) System
Room Temperature Phase Diagram of PLZT
with representative hysteresis loops at various compositions
La-Doped Lead Zirconate Titanate (PLZT) System
PbZrO3
Complex
relationship
between n
and E
Mole% PbZrO3
PbTiO3
n ~ E
n ~ E2
Room Temperature Phase Diagram of PLZT
showing different electro-optic characteristics at various compositions
La-Doped Lead Zirconate Titanate (PLZT) System
Electro-optic applications of PLZT ceramics depends on the composition
8/40/60 linear region
In the tetragonal ferroelectric (FT)
region  high EC hysteresis loops 
Linear electro-optic behavior for E < EC
(linear electro-optic modulators, and
optical switches)
In the rhombohedral ferroelectric (FR)
 Low EC hysteresis loops  Optical
memory applications (light valves,
optical-storage-display devices)
8/65/35 memory region
9/65/35 quadratic region
PLZT ceramic compositions with the
relaxor ferroelectric behavior are
characterized by a slim hysteresis loop
 Large quadratic electro-optic effects
for making flash protection goggles
La-Doped Lead Zirconate Titanate (PLZT) System
Examples of Applications of PLZT Ceramics
Flash Goggles : nuclear and arc radiations
Color Filter : optical shutter
Display : reflective display similar to LCD
Image Storage : strain-induced birefringence
Thin-Film Optical Switch
Photostriction