Lecture 3 Piezoelectric Materials (PDF Version)yyaman/avt086/Prasad/Eswar_Prasad_3.pdf ·...
Transcript of Lecture 3 Piezoelectric Materials (PDF Version)yyaman/avt086/Prasad/Eswar_Prasad_3.pdf ·...
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Piezoelectric Materials
• Piezoelectric Phenomena
— Piezoelectric Effect
— Modes of Vibration
— Terminology
• Materials and Processing
— Perovskite Materials
— Ceramic Processing
• Piezoelectric Applications
— Design Principles
— Application Examples
Lecture Outline
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Piezoelectric Materials
Piezoelectric Phenomena
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Piezoelectric Materials
• Piezoelectric behaviour can be manifested in two distinct
ways.
• ‘direct’ piezoelectric effect
• ‘converse’ piezoelectric effect
Piezoelectric Effect
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Piezoelectric Materials
• ‘Direct’ piezoelectric effect occurs when a piezoelectric
material becomes electrically charged when subjected to a
mechanical stress.
• These devices can be used to detect strain, movement,
force, pressure or vibration by developing appropriate
electrical responses, as in the case of force and acoustic
or ultrasonic sensors.
Direct Piezoelectric Effect
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Piezoelectric Materials
• ‘Converse’ piezoelectric effect occurs when the
piezoelectric material becomes strained when placed in an
electric field.
• This property can be used to generate strain, movement,
force, pressure or vibration through the application of
suitable electric field.
Converse Piezoelectric Effect
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Piezoelectric Materials
Terminology
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Piezoelectric Materials
Terminology
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Piezoelectric Materials
• When an electric field is applied to a piezoelectric,
the material dimensions change in all three axes
under stress-free conditions. The d constant
also expresses the amount of charge developedrelative to the stress applied along a specific axis.
Piezoelectric Strain Constant d
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Piezoelectric Materials
• The d31 constant is defined as:
Piezoelectric Strain Constant d
axis 1 along applied Stressarea electrode per Charge
axis 3 along applied Fieldaxis 1 along Developed Strain
d31
=
=
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Piezoelectric Materials
• The g constant expresses the electric fielddeveloped under open circuit conditions relative
to the stress applied along a specific axis. It
also expresses the amount of strain induced
relative to the applied electrical charge per unitarea.
Piezoelectric Stress Constant g
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Piezoelectric Materials
• The g31 constant is defined as:
Piezoelectric Stress Constant g
area electrodeper charge Appliedaxis 3 along developed Strain
axis 1 along applied Stressaxis 3 along developed Filed
g31
=
=
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Piezoelectric Materials
Hysteresis and Strain
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Piezoelectric Materials
Piezoelectric and Electrostrictive Effect
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Piezoelectric Materials
Modes of Vibration
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Piezoelectric Materials
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Crystal, Ceramics and Polymers
Type MaterialsSingle Crystals Quartz
Lead Magnesium Niobate(PMN-PT and PZN-PT)
Ceramics Lead Zirconate Titanate (PZT)Lead Metaniobate (LMN)Lead Titanate (LT)Lead Magnesium Niobate (PMN)
Polymers Polyvinylenedifluoride (PVDF)Composites Ceramic-polymer
Ceramic-glass
Piezoelectric Materials
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Piezoelectric Materials
Longitudinal Strain vs.Field for VariousMaterials
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Piezoelectric Materials
Structure of Lead Zirconate Titanate Ceramics
A2+ (Pb, Ba)B4+ (Ti, Zr)O2-
BM400 Type I (Pb, Sr)(Zr, Ti)O3BM500 Type II Pb(Zr,Ti,Nb)O3
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Piezoelectric Materials
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Soft Ceramics
Type of Piezoelectric Material Typical Properties
Soft Ceramics
Normally doped with NiobiumPentoxide or Lanthanum OxideLow Mechanical Q, High dielectricconstants and high chargesensitivity.
Examples of materials are:BM500 (Navy type II)BM527 (Navy type V)BM532 (Navy type VI)
Sensors, low power projectors,actuators, accelerometers.
Navy type ceramics refer to DOD-DTS-1376(SHIPS).
Piezoelectric Materials
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Piezoelectric Materials
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Piezoelectric Materials
Hard Ceramics
Type of Piezoelectric Material Typical PropertiesHard Ceramics
Normally doped with Nickel, Iron orStrontium. Typical characteristicsare high mechanical Q, lowerdielectric constant, lower lossfactor, higher resistance todepoling.
Examples of material are:BM400 (Navy type I)BM800 (Navy type III)
High power transducers in sonar,ultrasonic cleaning, high-driveactuators, biological celldisrupters
.
Navy type ceramics refer to DOD-DTS-1376(SHIPS).
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Piezoelectric Materials
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Piezoelectric Materials
Electrostrictive Ceramics
Type of Piezoelectric Material Typical Properties
Electrostrictive Ceramics
Normally produced from doped leadmagnesium niobate., Available forabout five years now, thesematerials have almost nohysteresis, very high dielectricconstants, very high straincoefficients.
Materials:BM600 (Modified LeadMagnesium Niobate)
Mainly used in actuators andvery high power sonar projectors.
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Piezoelectric Materials
Properties of Lead Zirconate Titanate Ceramics
Material ParameterPZT (II)BM500
PZT (VI)BM532
PZT (I)BM400
PZT (III)BM800
Dielectric Constant 1750 3250 1350 1000
Dissipation Factor%
2.0 2.0 0.4 0.2
Voltage Constant(g31) 10-3 Vm/N -11.5 -7.5 -10.5 -10.5
Charge Constant(d31) 10-12 C/N
-165 -250 -115 -80
Curie Temperature0C
360 210 350 325
Mechanic Q Factor 80 70 500 1000
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Piezoelectric Materials
Properties of Lead Zirconate Titanate Ceramics
Application PZT (II)BM500
PZT (VI)BM532
PZT (I)BM400
PZT (III)BM800
UnderwaterSonar ProjectorsHydrophonesDepth SoundersLinear Arrays
r
r
rr
rr
r
MeasurementLevel, FlowFlaw Detection (NDE)AccelerometersActuators
rrrr
rrrr
rrrr
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Piezoelectric Materials
Properties of Lead Zirconate Titanate Ceramics
Application PZT (II)BM500
PZT (VI)BM532
PZT (I)BM400
PZT (III)BM800
MedicalTransducersSteilizers
r r rr r
IndustrialCleanersAlarmsWelders
rr
r
r
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Piezoelectric MaterialsPiezoelect ric Materials
Processing of Lead Zirconate Titanate Ceramics
Ball mill
Spray dry
Calcine up to 1200oC
Weigh outraw material
Ball mill to desiredparticle size
Spray dry
Forming process:(dry or isostatic press etc.)
Sinter firing
Grinding or lapping
Powder evaluation
Electroding
Polarizing
Testing
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Piezoelectric Materials
Polarization of Ceramics
Polarization in asingle crystal ofpiezoelectricceramics.
Piezoelectric ceramic -before polarization
Piezoelectric ceramic - after polarization
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Piezoelectric Materials
Properties of Lead Zirconate Titanate Ceramics
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Piezoelectric Materials
Standard Ceramic Configurations
Frequency discs Thickness discs
Tubes
Plates and bars
Washers
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Piezoelectric Materials
Piezoelectric Tube Actuator
L
A W
31dLWVL ••=∆
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Piezoelectric Materials
Electrode Configurations for Tube Actuators
Outer/InnerElectrodesSegmented
180 DegOption 001
OuterElectrode
Segmented180 Deg
Option 002
Outer/InnerElectrodesSegmented
90 DegOption 003
OuterElectrode
Segmented90 Deg
Option 004
Outer/InnerFullFace
ElectrodesOption 005
No Segmentation
Option 005
One Horizontal Line
Option 006
Horizontal/Vertical Segments
Option 007
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Piezoelectric Materials
Piezoelectric Stack Actuator
L
33dNVL ••=∆
33dLtV
E
••=
EE s
dAtVF
33
33••=
A
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Piezoelectric Materials
Actuator Displacement and Force Working Equations
Assumption: Same Electric Field in Ceramics
•
•
∝
B
B
B
S
B
S
Lh
LL
dd
DD
31
33
•
•
•
∝
B
B
B
SE
E
B
S
hL
AA
ss
dd
FF
33
11
31
33
LS
AS
LB
AB
hB
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Piezoelectric Materials
Displacement and Force for Stack Actuator
Electric Field Constraints
! Coercive Field
(~ 500V/mm)
! Flashover Limit in Air
(~ 1000V/mm)
0006.0≈∆LL
∴ would need 17mm stackfor 10µm displacement.
AreaF ×≈ 30(F in Newtons, Area in mm2)
For 15mm OD & 5mm ID:
NF 4600≈
For Field = 1000 V/mm
Note: Exceeding coercivefield limit requires DC bias toavoid depoling.
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Piezoelectric Materials
Bending Mode Actuator
LB V hB DB
2
2
316B
BB h
LdVD •••=B
BBEB L
hWsdVF •••=
11
31
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Piezoelectric Materials
- 6
- 4
- 2
0
2
4
6
8
1 0
1 2
- 2 0 0 - 1 0 0 0 1 0 0 2 0 0
V o l tag e (V )
Dis
plac
emen
t (m
icro
ns).
Parallel to Field
Perpendicular to Field
Electrostrictive Actuator
25 x 25 mm2
20 mm
0.5 mm
A piezoelectric actuator of the same geometry and having the samedisplacements at 200V would require:
d33 = 1250pC/N; d31 = -460pC/N
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Piezoelectric Materials
Piezoelectric Composites
Piezoelectric composites consist of aceramic material embedded in a polymermatrix with a certain connectivity knownas 1-3 connectivity pattern. These elements offer several advantages oversingle-phase (monolithic) piezoelectricmaterials for such applications as
hydrophones and transducers. While not a flexible element, they canbe cut to very thin dimensions.
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Piezoelectric Materials
Piezoelectric Composites
1-3 composite
525±10%0.03 1475 ±5%0.62525-30%150kHz -1.5MHz
BM532
3250±10%0.031850±5%0.5870100150kHz -2MHz
Property
Dielectric ConstantK33T
Dissipation FactorN3Ke
Q (unloaded)Ceramic Volume
Frequency
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Piezoelectric Materials
Langevin-type transducers feature compactness, highenergy efficiency and a wide range of operatingtemperatures. These transducers use Lead ZirconateTitanate ceramic elements in a sandwich-typeconstruction (two to four discs), providing a ruggedunit capable of high efficiency and continuous operationat elevated temperatures.
Characteristic features:• Large amplitude• Low heat generation• Stability and durability• High efficiency• High output
Langevin Transducers
Langevin transducers can bebuilt from 18kHz to 70kHz forvarious end-user applications.
A booster horn can be used togenerate greater displacementfrom the transducer.
Applications:• Ultrasonic cleaning• Ultrasonic degreasers• Cell disrupters• Ultrasonic machining• Plastics welding• Underwater acoustics• Non-destructive evaluation• Atomizers• Ultrasonic scalpel
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Piezoelectric Materials
The electrical condition of an unstressed medium under
the influence of an electric field is defined by two
quantities - the field strength E and their dielectric
displacement D. These two are related by the equation:
D = ε E
where ε is the permittivity of the medium.
Piezoelectric Relations
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Piezoelectric Materials
The mechanical condition of the same medium at zero
electric field strength can be defined by two mechanical
quantities - applied stress T and strain S.
S = sT
where s is the compliance of the medium.
Piezoelectric Relations
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Piezoelectric Materials
Piezoelectricity involves the interaction between the
electrical and mechanical behaviour of the medium, and
the interaction can be described by linear relationships
between these two.
S = sE T + dE
D = dT + εT E
Piezoelectric Relations
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Piezoelectric Materials
1. Energy Conversion Mechanism
An externally applied electric field causes a change in the
dielectric polarization in the material which in turn causes
an elastic strain. The generating action takes place when
an elastic strain causes a change in the polarization that
induces a charge on the electrodes.
Principles of Application
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Piezoelectric Materials
2. Transducer Operating Environment
The acoustic properties of the medium (air, water or ice)
are very important in the design of transducers.
Transducers must also withstand the severe effects of
sea water, biological activity, hydrostatic pressure, and
extreme temperature conditions.
Principles of Application
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Piezoelectric Materials
3. Conversion Criteria
The following are the general performance criteria for the transducers.
• Linearity. The output of the transducer is a linear function of the
input.
• Reversibility. The transducer must convert energy in either direction.
• Passivity. All the output energy from the transducer is obtained from
the input energy - electrical or acoustical.
Principles of Application
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Piezoelectric Materials
Applications
Mechanical toElectricalConversion
! Phonograph cartridges! Microphones! Vibration sensors! Accelerometers! Photoflash actuators! Gas igniters! Fuses
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Piezoelectric Materials
Applications - Piezoelectric Igniters
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Piezoelectric Materials
Applications - Piezoelectric Igniters
NTK Ceramics, Japan, 1986.
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Piezoelectric Materials
Hydrophones
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Piezoelectric Materials
Applications - Diver Communication SystemsOcean technology S
ystems, 1990
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Piezoelectric Materials
Applications - Marine Mammal Listening Systems
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Piezoelectric Materials
Applications - Consumer Products
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Piezoelectric Materials
Applications
Electrical toMechanicalConversion
! Valves! Micropumps! Earphones and speakers! Ultrasonic cleaners! Emulsifiers! Sonic transducers
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Piezoelectric Materials
Applications - Piezoelectric Audiotone Transducers
Figure A. Layered structure with ceramic bonded to metal diaphragm. Radialmode of vibration produces a bending effect.Figure B. Alternating voltage produces convex and concave distortions in thediaphragm. Displacement of the diaphragm is in the order of microns.
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Piezoelectric Materials
Applications - Liquid Atomization Devices
1 2 3
1. Vibration; 2. Cavitation; 3. Misting4. Ultrasonic Humidifier.
4
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Piezoelectric Materials
Applications - Liquid Atomization Devices
Liquid Atomizing Nozzle from Sono-Tek Corporation. Fineliquid sprays are used in material processing industry suchas the manufacture of solar cells to provide thin uniformcoatings.
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Piezoelectric Materials
Applications - Liquid Atomization DevicesData from
Sono-Tek
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Piezoelectric Materials
Applications - Liquid Atomization Devices
Cavitation (at lower power levels)
Misting(at increased power levels)
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Piezoelectric Materials
Applications - Depth Sounders
NTK Technical Ceramics, 198
6.
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Piezoelectric Materials
Applications - Sonar Applications
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Piezoelectric Materials
Applications - Low Frequency Sonar
Sonar Dome
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Piezoelectric Materials
Applications - Low Frequency Sonar
Detail of the Sonar Transducerand the components of thesystem.Raytheon, 1984.
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Piezoelectric Materials
Applications - Ultrasonic MotorS
hinsei, 1996
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Piezoelectric Materials
Applications
Electrical-Mechanical-ElectricalConversion
! Surface acoustic wave devices! Delay lines! Filters! Oscillators! Transformers
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Piezoelectric Materials
Applications - Flash Blindness Goggles
Aura
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Piezoelectric Materials
TransducerSX100
DepthCompensator
MatchingNetwork
PowerAmplifierShield
SignalProcessor
PowerDistribution
Board
LithiumBatteryPack
AnodizedAluminumHousing
Underwater Communications
Piezoelectric Materials
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Piezoelectric Materials
Communication with Marine Mammals
Piezoelectric Materials
Transducer
Battery
ControlBox
Cable &Reel
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Piezoelectric Materials
Marine Mammal Communications
Piezoelectric Materials
Transmitter Receiver/Monitor
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Piezoelectric Materials
Conclusions
NTK Technical Ceramics, 198
6.
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Piezoelectric Materials
• Reviewed Piezoelectric Phenomena
— Piezoelectric Effect, Modes of Vibration, Terminology
• Materials and Processing
• Piezoelectric Applications
— Application examples using mechanical to electrical conversion, electricalto mechanical conversion, and electrical-mechanical-electrical conversionhave been discussed.
Conclusions