Transcript Piezo Material - Santa Rosa Junior College

Piezoelectric Material
A presentation by
Travis Heffernan & Monique Furtado
Engineering 45 Properties of Materials
Santa Rosa Junior College
Fall 2007 Younes Ataiiyan
Direct Piezoelectric Effect
Piezoelectric Material will generate electric
potential when subjected to some kind of
mechanical stress.
The direct Effect : Generator
F
F
• 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
Inverse Piezoelectric Effect
If the piezoelectric material is exposed to
an electric field (voltage) it consequently
lengthens or shortens proportional to the
voltage.
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.
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.
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.
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.
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.
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
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)
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
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
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)
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.
Our Experiment
Procedure
1)
2)
3)
4)
5)
6)
Attach a mirror to the piezoelectric buzzer. Position that laser so
that the beam can reflect off of the mirror and hit the wall across
the room.
Connect the function generator to the Piezoelectric device. Find
the resonant frequency of the device by slowly increasing the
frequency at 10Vp-p. The laser will vibrate the most at the resonant
frequency.
Measure the diameter of the laser without any signal. Then
measure the diameter of the laser with the AC signal applied.
Calculate the displacement of the laser and divide it by two to get
the amplitude of the magnified change in volume for the
piezoelectric material.
Measure the distance from the piezo to the wall and to the laser.
Also measure the height of the laser and reflected beam in relation
to the piezo.
Calculate the change in volume for the piezoelectric material.
Piezo Material at Resonance
Error Analysis
The laser’s diameter expands over a distance.
The quality of the mirror scatters the laser.
The sinusoidal vibration of the material amplifies the laser’s displacement.
Works Cited
•
Images:
1. http://en.wikipedia.org/wiki/Image:SchemaPiezo.gif
2.http://images.google.com/imgres?imgurl=http://www.hvwtech.com/products/266/35170_PV.jpg&imgrefurl=http://www.h
vwtech.com/products_view.asp%3FProductID%3D266&h=300&w=300&sz=6&hl=en&start=8&tbnid=AgpC2xR1AT9U
mM:&tbnh=116&tbnw=116&prev=
3. http://images.google.com/imgres?imgurl=http://surveying.wb.psu.edu/psusurv/SURIs/Images/NOAA_sonar.gif&imgrefurl=http://surveying.wb.psu.edu/psusurv/SURIs/hydrographic_surveying.htm&h=321&w=400&sz=54&hl=en&start=4&tbnid=CGIx7X99Z_4gDM:&tbnh=10
0&tbnw=124&prev=
4. http://images.google.com/imgres?imgurl=http://www.pc-control.co.uk/images/curie1.jpg&imgrefurl=http://www.pccontrol.co.uk/piezoelectric_effect.htm&h=177&w=136&sz=3&hl=en&start=31&tbnid=3GzV0hXv0pTPxM:&tbnh=101&t
bnw=78&prev=
5.http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer_2005/session1/2005_deer_troy.pdf
6. http://ch.mt.com/mt_ext_files/FilterHierarchy/ProductFamily/1/MX-UMX_FilterHierarchyProductFamily_1101466637484_files/micro_big.jpg
7.http://images.google.com/imgres?imgurl=http://euroross.blogspot.com/Moscow%2520Traffic%25202.jpg&imgrefurl=http
://euroross.blogspot.com/2006_11_01_euroross_archive.html&h=301&w=392&sz=28&hl=en&start=3&tbnid=xLHUTcd9I7-0M:&tbnh=94&tbnw=123&prev=
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:&tb
nh=86&tbnw=130&prev=
•
1.
2.
3.
4.
5.
6.
7.
8.
9.
Information:
http://www.piezo.com/tech1terms.html
http://www.piezo.com/tech4history.html
http://www.piezoelectrics.net/piezoelectrichistory.htm
http://www.americanpiezo.com/piezo_theory/index.html
http://www.cedrat-groupe.com/
http://www.sensotec.com/accelerometer_faq.asp?category=All
http://www.apple.com/iphone/features/index.html#accelerometer
http://www.patent-invent.com/electricity/inventions/piezoelectricity.html
http://en.wikipedia.org/wiki/Piezoelectricity