1. 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 high-temperature 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 = (strain > 6%))
Modified compositions with various dopant ( 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
Lattice constants versus temperature for PbTiO3

2. (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 

3. Antiferroelectricity

4. Antiferroelectricity
Anti-ferroelectric materials  Non-polar, Non-ferroelectric materials that revert to a ferroelectric state when subjected to sufficiently high electric field, causing a “double-loop hysteresis”

5. 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

6. Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
PZT Solid Solution Phase Diagram
Zr/Ti ratio 52/48 MPB

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. Compositions and Modifications of PZT System
Dependence of dielectric and piezoelectric properties on average grain size in the ceramic Pb(Zr0.51Ti0.49)O wt% MnO2 at a constant density of g/cm3 
Piezoelectric properties increase linearly with increasing grain size

16. 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 

17. 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”

18. Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Dielectric constant vs temperature of various types PZT materials

19. Modified PZT System 3.1 Hard Doping: Hard PZT “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 Pb2+ replaced by two K+ ions OR Two Zr4+ (or Ti4+) replaced by two Fe3+ ions
Space charges inhibit domain motion and Insoluble doped ions inhibit grain growth
Increased Qm and Ec, Decreased loss tangent, and Lowered dielectric and piezoelectric activities
“Hard PZT”
Rugged Applications
(High Temperature and High Driving Loads)

20. Modified PZT System 3.2 Soft Doping: Soft PZT “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)

21. Modified PZT System “Hard PZT” Materials “Soft 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

22. 3.3 Other Doping Ions (Ce, Cr, U, Ag, Ir, Rh, Ni, Mn, Nb, Al)
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

23. Examples of Practical Modified PZT System
Materials for ceramic filters:
1.1 Range MHz (modified PT)
0.99[0.96PbTiO La2/3TiO3] MnO2
1.2 Range MHz
Pb1.03[(Nb2O6)0.07(CrO2)0.03(Zr0.52Ti0.48O3)0.90] wt%MnO2 + 1 wt% La2O3
1.3 Range 1-10 MHz
Pb0.95Sr0.05Mg0.03(Zr0.52Ti0.48)O wt%CeO wt% MnO2
Materials for underwater ultrasonic transducers:
Pb0.95Sr0.05 (Zr0.54Ti0.46)O wt%La2O wt% Nb2O5
3. Materials for high-voltage generator:
[Pb(Nb1/2Sb1/2)O3]0.05 [PbTiO3]0.41 [PbZrO3]0.54
+ 0.2 mol%Nb2O mol%Y2O wt% MnO2
4. Materials for electro-acoustic applications:
[Pb(Ni1/3Nb2/3)O3]0.50 [PbTiO3]0.355 [PbZrO3]0.145

24. Lead Zirconate Titanate (Pb (Zrx Ti1-x)O3 or PZT) System
Examples of Commercially Available PZT from APC

25. 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

26. 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 La3+ 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

27. 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 
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
Phase Diagram of the PZT and PLZT Solid-Solution Systems

28. La-Doped Lead Zirconate Titanate (PLZT) System
MPB
Ferroelectric tetragonal and rhombohedral phases
Pyroelectric Applications
Orthorhombic
Anti-ferroelectric phases
Cubic
paraelectric phases
MPB Compositions for transducer applications
Diffused metastable relaxor (electrically inducible to ferroelectric)
for quadratic strain and electro-optics
Phase Diagram of the PZT and PLZT Solid-Solution Systems

29. La-Doped Lead Zirconate Titanate (PLZT) System
Room Temperature Phase Diagram of PLZT
with representative hysteresis loops at various compositions

30. La-Doped Lead Zirconate Titanate (PLZT) System
PbZrO3
PbTiO3
Mole% PbZrO3
Complex relationship between n and E
n ~ E
n ~ E2
Room Temperature Phase Diagram of PLZT
showing different electro-optic characteristics at various compositions

31. La-Doped Lead Zirconate Titanate (PLZT) System
Electro-optic applications of PLZT ceramics depends on the composition
8/40/60 linear region
8/65/35 memory region
9/65/35 quadratic 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)
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

32. 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