This document discusses piezoelectric ceramics, including their fabrication, processing, applications, and references. Piezoelectric ceramics are made by mixing metal oxide powders, forming them into structures, and firing them to form a crystalline structure. They are then poled by applying an electric field to align dipole moments. Common piezoelectric ceramics include barium titanate and lead zirconate titanate. Applications include sensors, actuators, transducers, generators, and motors that convert mechanical and electrical energy.

1. Bahir Dar University
By:
Biruk Gedif
Material Science and Engineering
Piezoelectric Ceramics
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2. Outline
1.Introduction
2. Fabrication
3.Processing
4.Applications
5. References
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3. Introduction
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What is piezoelectric?
 It a Greek word:
 Pizo or piezein  squeeze or press and
 electron,  amber, an ancient source of
electric charge.

4. What is piezoelectric?
 Piezoelectricity is a concept of conversion of
mechanical energy to electrical energy and vice
versa, not by any electromagnetic principle but by
the process of Polarization.
 Piezo-electricity, or pressure electricity, is defined
as polarization induced by the application of
external force.
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5. BDU-MaS
Hence the piezoelectric effect exists in two domains.
Piezoelectricity is defined as a change in electric
polarization with a change in applied stress
Compression
Effect: Decrease in volume and it has a
voltage with the same polarity as the
material
Tension
Effect: Increase in volume and it has a
voltage with opposite polarity as the material
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1. Direct piezoelectric effect:
Jacques Curie
Pierre Curie
Discovered in 1880

6. If the applied voltage has the
opposite polarity then the material
contracts.
Discovered in 1881
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2. Reverse piezoelectric effect
The change of strain or stress in a material due to an applied electric field.
If the applied voltage has the same
polarity then the material expands.

7. https://www.youtube.com/watch?v=4nbBAG-848c
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8. The microscopic origin of the piezoelectric effect is the displacement of
ionic charges within a crystal structure.
 In the absence of external strain, the charge distribution is
symmetric and the net electric dipole moment is zero.
 However when an external stress is applied, the charges are
displaced and the charge distribution is no longer symmetric and a
net polarization is created.
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9.  In order to create a net piezoelectric effect, the material
must be:
a. a pure crystal (difficult to realize in most
cases)
b. the crystal domains must be brought into
alignment during poling .
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10. Operational Limits of Piezoelectric Materials
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 During normal operation, a piezoelectric material is either strained (to
create an electric potential) or is subjected to an electric potential (to
create a strain).
However, care must be taken to operate the material within the parameters
specified by the manufacturer.
 Electrical depolarization can occur if a piezoelectric material is
subjected to extreme electric fields (or voltages) which will cause it to
lose (or significantly degrade) its piezoelectric effects.

11.  Mechanical depolarization can occur if a material is excessively
strained to the point where the crystal domains are significantly
disturbed.
 Thermal depolarization can occur if a material subjected to
temperatures beyond the ‘Curie point’ of the material.
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……………Cont. ………..

12. Fine powders of the component metal oxides are mixed in specific proportions, then
heated to form a uniform powder.
The powder is mixed with an organic binder and is formed into structural elements.
The elements are fired according to a specific time and temperature program, during
which the powder particles sinter and the material attains a dense crystalline
structure.
The elements are cooled, then shaped or trimmed to specifications. Electrodes are
applied to a conducting material, which is connected to the elements.
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How are Piezoelectric ceramics made?

13. Crystal Structure and DipoleMoments
A traditional piezoelectric ceramic is a mass of perovskite crystals.
Each crystal consists of a small tetravalent metal ion, usually titanium
or zirconium, in a lattice of larger divalent metal ions, usually lead
or barium, and O2− ions
At temperatures below the Curie point, however, each crystal has
tetragonal or rhombohedral symmetry and a dipole moment.
Above the Curie point each perovskite crystal in the fired ceramic
element exhibits a cubic symmetry with no dipole moment.
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14. Processing of Piezoelectric Ceramic
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No. Stages Processing Intermediary products
1
Elaboration of the
ceramic powder
dosage Ceramic powder
homogenization
milling
calcination
milling
properties testing
2
Elaboration of bulk
ceramic
shaping
Ceramic plates – active
piezoelectric elements
pressing
sintering
cutting/ lapping/polishing
electrical poling
morphological/structural
investigation
properties testing

15. Types of Piezoelectric Materials
1. Naturally occurring crystals: Berlinite (AlPO4), cane sugar, Quartz, Rochelle
salt, Topaz, Tourmaline Group Minerals, and dry bone (apatite crystals)
2. Man-made crystals: Gallium orthophosphate (GaPO4), Langasite
(La3Ga5SiO14)
3. Man-made ceramics: Barium titanate (BaTiO3), Lead titanate (PbTiO3),
Lead zirconate titanate - more commonly known as PZT, Potassium niobate
(KNbO3), Lithium niobate (LiNbO3), Lithium tantalate (LiTaO3)
4. Polymers: Polyvinylidene fluoride (PVDF)
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16.  The principle is adapted to piezoelectric motors, sound or ultrasound generating devices,
and many other products.
 Generator action is used in fuel-igniting devices, solid state batteries, and other
products;
 Motor action is adapted to piezoelectric motors, sound or ultrasound generating
devices, and many other products.
 Generators Sensors ActuatorsTransducers
 Transducers: convert mechanical energy into electrical energy (or vice versa)
e.g. Mechanical to electrical: record player, strain gauge, cigarette lighter.
e.g. Electrical to mechanical: production of ultrasonic waves.BDU-MaSE-PiezolectricCeramic 16
Applications of Piezoelectric ceramics

17. Loudspeaker
Actuators
Piezoelectric motors
Valves
Nanopositioning inAFM,
STM
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……………Cont. ………..

18. pressure sensor Force sensor Strain gaugeMicrophone
Sensors
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……………Cont. ………..

19. High voltage and power source
Cigarette lighter Energy harvesting AC voltage multiplier
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20. References
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21. Thank You!!
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