Piezoelectric MaterialPiezoelectric Material

A presentation by A presentation by Travis Heffernan & Monique FurtadoTravis Heffernan & Monique Furtado

Engineering 45 Properties of MaterialsEngineering 45 Properties of MaterialsSanta Rosa Junior CollegeSanta Rosa Junior CollegeFall 2007 Younes AtaiiyanFall 2007 Younes Ataiiyan

Direct Direct Piezoelectric EffectPiezoelectric Effect

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

The The direct direct Effect : GeneratorEffect : Generator• Compression Compression

Effect: Decrease in Effect: Decrease in volume and it has a volume and it has a voltage with the same voltage with the same polarity as the materialpolarity as the material

• TensionTensionEffect: Increase in Effect: Increase in volume and it has a volume and it has a voltage with opposite voltage with opposite polarity as the materialpolarity as the material

F

F

InverseInverse Piezoelectric Effect Piezoelectric Effect

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

The The Inverse Piezoelectric Inverse Piezoelectric Effect Effect

• If the applied voltage has If the applied voltage has the same polarity then the same polarity then the material expands.the material expands.

• If the applied voltage has If the applied voltage has the opposite polarity the opposite polarity then the material then the material contracts.contracts.

The History of PiezoThe History of Piezo• The name Piezo The name Piezo

originates from the originates from the Greek word Greek word piezeinpiezein, , which means to which means to squeeze or press.squeeze or press.

• The piezoelectric The piezoelectric effect was first effect was first proven in 1880 by proven in 1880 by the brothers Pierre the brothers Pierre and Jacques Curie.and Jacques Curie.

    

Developing theories…Developing theories…• Pierre and Jacques Curie predicted and Pierre and Jacques Curie predicted and

demonstrated the piezoelectric effect using demonstrated the piezoelectric effect using tinfoil, glue, wire, magnets, and a jeweler’s saw.tinfoil, glue, wire, magnets, and a jeweler’s saw.

• They showed that crystals of tourmaline, quartz, They showed that crystals of tourmaline, quartz, topaz, cane sugar, and Rochelle salt generate topaz, cane sugar, and Rochelle salt generate electrical polarization from mechanical stress.electrical polarization from mechanical stress.

• The converse effect was mathematically derived The converse effect was mathematically derived by Gabriel Lippman in 1881 using fundamental by Gabriel Lippman in 1881 using fundamental thermodynamic principles and was later thermodynamic principles and was later experimentally confirmed by the Curies.experimentally confirmed by the Curies.

How are Piezoelectric ceramics How are Piezoelectric ceramics made?made?

• Fine powders of the component metal oxides are Fine powders of the component metal oxides are mixed in specific proportions, then heated to form mixed in specific proportions, then heated to form a uniform powder. a uniform powder.

• The powder is mixed with an organic binder and is The powder is mixed with an organic binder and is formed into structural elements.formed into structural elements.

• The elements are fired according to a specific The elements are fired according to a specific time and temperature program, during which the time and temperature program, during which the powder particles sinter and the material attains a powder particles sinter and the material attains a dense crystalline structure. dense crystalline structure.

• The elements are cooled, then shaped or trimmed The elements are cooled, then shaped or trimmed to specifications. Electrodes are applied to a to specifications. Electrodes are applied to a conducting material, which is connected to the conducting material, which is connected to the elements. elements.

Crystal Structure and Crystal Structure and Dipole MomentsDipole Moments

• A traditional piezoelectric ceramic is A traditional piezoelectric ceramic is a mass of perovskite crystals. Each a mass of perovskite crystals. Each crystal consists of a small crystal consists of a small tetravalent metal ion, usually tetravalent metal ion, usually titanium or zirconium, in a lattice of titanium or zirconium, in a lattice of larger divalent metal ions, usually larger divalent metal ions, usually lead or barium, and O2- ions lead or barium, and O2- ions

• At temperatures below the Curie At temperatures below the Curie point, however, each crystal has point, however, each crystal has tetragonal or rhombohedral tetragonal or rhombohedral symmetry and a dipole moment. symmetry and a dipole moment. Above the Above the Curie pointCurie point each each perovskite crystal in the fired perovskite crystal in the fired ceramic element exhibits a cubic ceramic element exhibits a cubic symmetry with no dipole moment. symmetry with no dipole moment.

Polarizing Piezoelectric Polarizing Piezoelectric MaterialMaterial• Adjoining dipoles form regions of local alignment called Adjoining dipoles form regions of local alignment called

domainsdomains. The alignment gives a net dipole moment to the . The alignment gives a net dipole moment to the domain, and thus a net polarization. The direction of domain, and thus a net polarization. The direction of polarization among neighboring domains is random, polarization among neighboring domains is random, however, so the ceramic element has no overall however, so the ceramic element has no overall polarization.polarization.

• The domains in a ceramic element are aligned by exposing The domains in a ceramic element are aligned by exposing the element to a strong, direct current electric field, usually the element to a strong, direct current electric field, usually at a temperature slightly below the Curie point at a temperature slightly below the Curie point

• When the electric field is removed most of the dipoles are When the electric field is removed most of the dipoles are locked into a configuration of near alignment locked into a configuration of near alignment

Types of Piezoelectric Types of Piezoelectric MaterialsMaterials• Naturally occurring crystalsNaturally occurring crystals: :

Berlinite (AlPO4), cane sugar, Quartz, Rochelle salt, Topaz, Berlinite (AlPO4), cane sugar, Quartz, Rochelle salt, Topaz, Tourmaline Group Minerals, and dry bone (apatite crystals)Tourmaline Group Minerals, and dry bone (apatite crystals)

• Man-made crystalsMan-made crystals: : Gallium orthophosphate (GaPO4), Langasite (La3Ga5SiO14) Gallium orthophosphate (GaPO4), Langasite (La3Ga5SiO14)

• Man-made ceramics:Man-made ceramics: Barium titanate (BaTiO3), Lead titanate (PbTiO3), Lead Barium titanate (BaTiO3), Lead titanate (PbTiO3), Lead zirconate titanate (Pb[Zrzirconate titanate (Pb[ZrxxTi1-Ti1-xx]O3 0<]O3 0<xx<1) - More <1) - More commonly known as commonly known as PZTPZT, Potassium niobate (KNbO3), , Potassium niobate (KNbO3), Lithium niobate (LiNbO3), Lithium tantalate (LiTaO3), Lithium niobate (LiNbO3), Lithium tantalate (LiTaO3), Sodium tungstate (NaxWO3), Ba2NaNb5O5, Pb2KNb5O15 Sodium tungstate (NaxWO3), Ba2NaNb5O5, Pb2KNb5O15

• Polymers:Polymers:Polyvinylidene fluoride (PVDF) Polyvinylidene fluoride (PVDF)

Sonic and Ultrasonic Sonic and Ultrasonic ApplicationsApplications

• Sonar with Ultrasonic Sonar with Ultrasonic time-domain time-domain reflectometers reflectometers

• Materials testing to Materials testing to detect flaws inside cast detect flaws inside cast metals and stone metals and stone objects as well as objects as well as measure elasticity or measure elasticity or viscosity in gases and viscosity in gases and liquidsliquids

• Compact sensitive Compact sensitive microphones and guitar microphones and guitar pickups.pickups.

• LoudspeakersLoudspeakers

Pressure ApplicationsPressure Applications• Transient pressure measurement Transient pressure measurement

to study explosives, internal to study explosives, internal combustion engines (knock combustion engines (knock sensors), and any other vibrations, sensors), and any other vibrations, accelerations, or impacts.accelerations, or impacts.

• Piezoelectric microbalances are Piezoelectric microbalances are used as very sensitive chemical used as very sensitive chemical and biological sensors.and biological sensors.

• Transducers are used in electronic Transducers are used in electronic drum pads to detect the impact of drum pads to detect the impact of the drummer's sticks.the drummer's sticks.

• Energy Harvesting from impact on Energy Harvesting from impact on the groundthe ground

• Atomic force and scanning Atomic force and scanning tunneling microscopes.tunneling microscopes.

• Electric igniters and cigarette Electric igniters and cigarette lighterslighters

Consumer Electronics Consumer Electronics ApplicationsApplications

• Quartz crystals resonators Quartz crystals resonators as frequency stabilizers as frequency stabilizers for oscillators in all for oscillators in all computers.computers.

• Phonograph pick-ups Phonograph pick-ups • Accelerometers: In a Accelerometers: In a

piezoelectric piezoelectric accelerometer a mass is accelerometer a mass is attached to a spring that attached to a spring that is attached to a is attached to a piezoelectric crystal. piezoelectric crystal. When subjected to When subjected to vibration the mass vibration the mass compresses and stretches compresses and stretches the piezo electric crystal. the piezo electric crystal. (iPhone)(iPhone)

Motor ApplicationsMotor Applications• Piezoelectric elements can be Piezoelectric elements can be

used in laser mirror alignment, used in laser mirror alignment, where their ability to move a where their ability to move a large mass (the mirror mount) large mass (the mirror mount) over microscopic distances is over microscopic distances is exploited. By electronically exploited. By electronically vibrating the mirror it gives the vibrating the mirror it gives the light reflected off it a Doppler light reflected off it a Doppler shift to fine tune the laser's shift to fine tune the laser's frequency. frequency.

• The piezo motor is viewed as a The piezo motor is viewed as a high-precision replacement for high-precision replacement for the stepper motor. the stepper motor.

• Traveling-wave motors used Traveling-wave motors used for auto-focus in cameras.for auto-focus in cameras.

Our ExperimentOur Experiment

ProcedureProcedure1)1) Attach a mirror to the piezoelectric buzzer. Position that laser Attach a mirror to the piezoelectric buzzer. Position that laser

so that the beam can reflect off of the mirror and hit the wall so that the beam can reflect off of the mirror and hit the wall across the room.across the room.

2)2) Connect the function generator to the Piezoelectric device. Connect the function generator to the Piezoelectric device. Find the resonant frequency of the device by slowly Find the resonant frequency of the device by slowly increasing the frequency at 10Vincreasing the frequency at 10Vp-p. p-p. The laser will vibrate the The laser will vibrate the most at the resonant frequency.most at the resonant frequency.

3)3) Measure the diameter of the laser without any signal. Then Measure the diameter of the laser without any signal. Then measure the diameter of the laser with the AC signal applied.measure the diameter of the laser with the AC signal applied.

4)4) Calculate the displacement of the laser and divide it by two Calculate the displacement of the laser and divide it by two to get the amplitude of the magnified change in volume for to get the amplitude of the magnified change in volume for the piezoelectric material.the piezoelectric material.

5)5) Measure the distance from the piezo to the wall and to the Measure the distance from the piezo to the wall and to the laser. Also measure the height of the laser and reflected laser. Also measure the height of the laser and reflected beam in relation to the piezo.beam in relation to the piezo.

6)6) Calculate the change in volume for the piezoelectric material. Calculate the change in volume for the piezoelectric material.

Piezo Material at ResonancePiezo Material at Resonance

Error AnalysisError AnalysisThe laser’s diameter expands over a distance. The laser’s diameter expands over a distance. The quality of the mirror scatters the laser. The quality of the mirror scatters the laser. The sinusoidal vibration of the material amplifies the laser’s displacement. The sinusoidal vibration of the material amplifies the laser’s displacement.

Works CitedWorks Cited• Images:Images:1. 1. http://en.wikipedia.org/wiki/Image:SchemaPiezo.gif2.2.

http://images.google.com/imgres?imgurl=http://www.hvwtech.com/products/266/35170_PV.jpg&imgrefurl=http://www.hvwtech.com/products_view.asp%3FProductID%3D266&h=300&w=300&sz=6&hl=en&start=8&tbnid=AgpC2xR1AT9UmM:&tbnh=116&tbnw=116&prev==

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5.5.http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2005/session1/2005_deer_troy.pdf6. 6.

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8.8.http://images.google.com/imgres?imgurl=http://farm1.static.flickr.com/116/252342964_2fffa201a8.jpg&imgrefurl=http://www.flickr.com/photos/surrendo/252342964/&h=331&w=500&sz=225&hl=en&start=107&tbnid=BlgpiI13s1UQ8M:&tbnh=86&tbnw=130&prev==

• Information:Information:1. http://www.piezo.com/tech1terms.html2. http://www.piezo.com/tech4history.html3.3. http://www.piezoelectrics.net/piezoelectrichistory.htmhttp://www.piezoelectrics.net/piezoelectrichistory.htm4.4. http://www.americanpiezo.com/piezo_theory/index.htmlhttp://www.americanpiezo.com/piezo_theory/index.html5.5. http://www.cedrat-groupe.com/http://www.cedrat-groupe.com/6.6. http://www.sensotec.com/accelerometer_faq.asp?category=Allhttp://www.sensotec.com/accelerometer_faq.asp?category=All7.7. http://www.apple.com/iphone/features/index.html#accelerometerhttp://www.apple.com/iphone/features/index.html#accelerometer8.8. http://www.patent-invent.com/electricity/inventions/piezoelectricity.htmlhttp://www.patent-invent.com/electricity/inventions/piezoelectricity.html9.9. http://en.wikipedia.org/wiki/Piezoelectricityhttp://en.wikipedia.org/wiki/Piezoelectricity