homebrew piezoelectric crystal

7/29/2019 Homebrew Piezoelectric Crystal

1/19

Homebrew PiezoelectricCrystal

(Potassium Sodium Tartrate, also known as, Rochelle Salt)

Abraham Carrillo

Luis Molina

Isai Onofre

Engr. 45, Fall 2011

Younes Ataiiyan


2/19

What arePiezoelectrics?

Materials with piezoelectricproperties produce an electricalcharge when mechanical pressure isapplied.

Interestingly, when the mechanical

pressure is reversed (fromcompression to tension) the sign ofthe electric charge change.

Piezoelectric materials will alsoexpand if you send an electricalcharge through it.

Their applications include using themin speakers, ultrasonic imaging,rocket propelled grenades, light upshoes, and watches.


3/19

Materials with

Piezoelectric propertiesCrystals (natural)Quartz

Rochelle Salt

Topaz

Sucrose (table sugar)

Ceramics (man-made)

Barium titanate (BaTiO3)

Lead titanate (PbTi3)

Lithium niobate (LiNb3)

Lithium tanalate (LiTaO3)


4/19

Lab Methods of growing

Natural CrystalsCzochralski MethodOne attaches a crystal seed at thebottom of a vertical arm such that theseed is barely in contact with thesurface of the melt

As the arm is raised slowly, crystalsbegin to form under the the tip of theseed. As the seed is pulled, morecrystals form.

The computer-controlled arm can varythe pull rate to produce the desired

diameter

As the material solidifies (crystallizes) itforms a large circular boule

Boule


5/19

Bridgman-Stockbarger Method

Polycrystalline material is deposited insidea sealed ampoule (similar to a pipette)

The material is heated up inside a ceramic

tube which has a gradient temperature

The heaters will melt the material andmaintain it at a molten state. As theampoule is lowered, crystals begin to growat the conical tip. The ampoule is loweredat the rate of crystal formation.

When performed correctly a boule ofcrystal is formed.

Method creates some impurities


6/19

How to make Piezoelectric

CeramicsAll ceramics are man-made and are forced to becomepiezoelectric through a process of polarization

The process of poling exposes ceramic material to a

high-intensity electric field which aligns the the electricdipoles and causes the ceramic to become piezoelectric

Unfortunately the process tends to reverse itself overtimeuntil it exponentially reaches a steady state ( loses some

of its piezoelectricity). Also exposure to hightemperatures, high levels of static charge and electricfields approaching its poling voltage, can cause ceramicsto lose their piezoelectric properties prematurely.


7/19

Potassium Sodium Tartrate

(Rochelle Salt)First produced in 1675 by Pierre Seignette, a pharmacist fromFrance.

It was proven to have piezoelectric properties in 1880 by PierreCurie and Jacques Curie.

Was first used in microphones, speakers, gramophones duringWWII.

Use of Rochelle Salt stopped because it is soluble in water, and thecrystals degraded over time.

Medicinally used as a laxative.

Used in the process of silvering mirrors.


8/19

Ingredients for Rochelle Salt

Sodium Carbonate (Na2CO3, Soda Ash). Soda Ash can be found inArt stores.

Potassium Bitartrate (KHC4H4O6, Cream of tartar). Cream of tartarcan be found in the spice sections in grocery stores.

250 mL water (H20).


9/19


10/19

TrialsThe first solution we mixed was notsuccessful, and may have been because webought a substitute for Cream of tartar, ormixed the solution too fast for the reactionto react.

We spent two hours mixing this batch, andwe only ended up with a useless slush.

The second solution we mixed, wepurchased the more expensive Cream ofTartar, and spent over 4 hours mixing thesolution.

After one night, several crystals formed anda few were removed to use as seed crystals.More crystals formed for a week, but all verysmall and untestable.

After several seed crystals were chosen, therest were to be used in a supersaturatedsolution for crystal growth.


11/19

Seed Crystal Vs. Grown Crystal


12/19

Testing Apparatus design

Wave Generator


13/19


14/19

Testing


15/19

Resonance


16/19

Failed LED Test


17/19

Future Application:Piezoelectricity from

California Roadways

Assemblyman Mike Gatto hasproposed using piezoelectrictechnology on highways as apower-generating source (BillAB 306).

Technology would create asmuch as 44 megawatts ofelectricity a year, for a singlelane, 1 km long strip of road.This is enough to power 30,800homes for a year.

Project would consist of placingcheap piezoelectric sensorsunderneath roads. Vibrationsfrom cars would be convertedinto electricity, which couldeasily power signs and lights.

A similar system is already inuse in Israel and Italy.


18/19

A Special Thanks to

MESA (AKA Darci Rosales) for providing Legos

Physics Department for the Oscilloscope, function

Generator, and LEDsProfessor Younes Ataiiyan for providing copper foiland help on our test.

Luis for gracing us with his swag.


19/19

http://www.seawhy.com/xlroch.html

http://www.pcb.com/techsupport/tech_accel.php

http://www.stanford.edu/group/scintillators/scintillators.html

www.virtualacquisitionshowcase.com/document/1193/brochure

http://inhabitat.com/piezoelectric-energy-generating-roads-proposed-for-california/piezogenerator/
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