Piezoelectric materials generate an electric charge when subjected to mechanical stress. This is known as the direct piezoelectric effect. The converse effect occurs when an electric field is applied to the material, causing it to change shape. Common piezoelectric materials include crystals like quartz as well as man-made ceramics. These materials find applications in technologies like sonar, accelerometers, lighters, and motors due to their ability to convert between mechanical and electrical energy.

1. Piezoelectric
Materials

2. Direct Piezoelectric Effect
Piezoelectric Material will generate electric potential
when subjected to some kind of mechanical stress.

3. The direct Effect : Generator
 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
F
F

4. Inverse Piezoelectric Effect
If the piezoelectric material is exposed to an electric
field (voltage) it consequently lengthens or shortens
proportional to the voltage.

5. The Inverse Piezoelectric Effect
 If the applied voltage has
the same polarity then the
material expands.
 If the applied voltage has
the opposite polarity then
the material contracts.

6. The History of Piezo
 The name Piezo
originates from the
Greek word piezein,
which means to
squeeze or press.
 The piezoelectric
effect was first proven
in 1880 by the
brothers Pierre and
Jacques Curie.

7. Developing theories…
 Pierre and Jacques Curie predicted and
demonstrated the piezoelectric effect using tinfoil,
glue, wire, magnets, and a jeweler’s saw.
 They showed that crystals of tourmaline, quartz,
topaz, cane sugar, and Rochelle salt generate
electrical polarization from mechanical stress.
 The converse effect was mathematically derived by
Gabriel Lippman in 1881 using fundamental
thermodynamic principles and was later
experimentally confirmed by the Curies.

8. How are Piezoelectric
ceramics made?
 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.

9. Crystal Structure and
Dipole Moments
 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.

10. Polarizing Piezoelectric Material
 Adjoining dipoles form regions of local alignment called domains.
The alignment gives a net dipole moment to the domain, and thus a
net polarization. The direction of polarization among neighboring
domains is random, however, so the ceramic element has no overall
polarization.
 The domains in a ceramic element are aligned by exposing the
element to a strong, direct current electric field, usually at a
temperature slightly below the Curie point
 When the electric field is removed most of the dipoles are locked
into a configuration of near alignment

11. Types of Piezoelectric
Materials
 Naturally occurring crystals:
Berlinite (AlPO4), cane sugar, Quartz, Rochelle salt, Topaz,
Tourmaline Group Minerals, and dry bone (apatite crystals)
 Man-made crystals:
Gallium orthophosphate (GaPO4), Langasite (La3Ga5SiO14)
 Man-made ceramics:
Barium titanate (BaTiO3), Lead titanate (PbTiO3), Lead zirconate
titanate (Pb[ZrxTi1-x]O3 0<x<1) - More commonly known as PZT,
Potassium niobate (KNbO3), Lithium niobate (LiNbO3), Lithium
tantalate (LiTaO3), Sodium tungstate (NaxWO3), Ba2NaNb5O5,
Pb2KNb5O15
 Polymers:
Polyvinylidene fluoride (PVDF)

12. Sonic and Ultrasonic Applications
 Sonar with Ultrasonic
time-domain
reflectometers
 Materials testing to detect
flaws inside cast metals
and stone objects as well
as measure elasticity or
viscosity in gases and
liquids
 Compact sensitive
microphones and guitar
pickups.
 Loudspeakers

13. Pressure Applications
 Transient pressure measurement to
study explosives, internal combustion
engines (knock sensors), and any
other vibrations, accelerations, or
impacts.
 Piezoelectric microbalances are used
as very sensitive chemical and
biological sensors.
 Transducers are used in electronic
drum pads to detect the impact of the
drummer's sticks.
 Energy Harvesting from impact on the
ground
 Atomic force and scanning tunneling
microscopes.
 Electric igniters and cigarette lighters

14. Consumer Electronics Applications
 Quartz crystals resonators as
frequency stabilizers for
oscillators in all computers.
 Phonograph pick-ups
 Accelerometers: In a
piezoelectric accelerometer a
mass is attached to a spring
that is attached to a
piezoelectric crystal. When
subjected to vibration the
mass compresses and
stretches the piezo electric
crystal. (iPhone)

15. Motor Applications
 Piezoelectric elements can be
used in laser mirror alignment,
where their ability to move a large
mass (the mirror mount) over
microscopic distances is exploited.
By electronically vibrating the
mirror it gives the light reflected
off it a Doppler shift to fine tune
the laser's frequency.
 The piezo motor is viewed as a
high-precision replacement for
the stepper motor.
 Traveling-wave motors used for
auto-focus in cameras.