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Piezoelectric Piezoelectric MaterialsMaterials
Derek SandersonDerek SandersonTulane University Chemical EngineeringTulane University Chemical Engineering
Advisor: Prof. Keith BowmanAdvisor: Prof. Keith Bowman
Cancerous Tissue AblationCancerous Tissue Ablation
IdeaIdea array of ultrasound array of ultrasound
transducerstransducers concentrate energyconcentrate energy destroy cancerous tissuedestroy cancerous tissueNeedsNeeds ablation strength pulseablation strength pulseRestrictionsRestrictions close proximityclose proximity small sizesmall size internal body tempinternal body temp
Perovskite StructurePerovskite Structure
Simple cube of A’s + face-Simple cube of A’s + face-centered C’s + body-centered centered C’s + body-centered BB
AA BB CCPbPb2+2+ (Zr/Ti)(Zr/Ti)4+4+ OO33
2-2-
cubiccubic central B-site cationcentral B-site cation paraelectricparaelectric not lowest energynot lowest energy
tetragonal/rhomb.tetragonal/rhomb. shifted B-site cationshifted B-site cation ferroelectricferroelectric lower energylower energy
MicroscopicMicroscopic
cubic structure at cubic structure at high temp.high temp.
cooling below Curie cooling below Curie temp. (Ttemp. (Tcc))
tetra./rhomb.tetra./rhomb. non centrosymmetricnon centrosymmetric c/a < 1.005c/a < 1.005
MacroscopicMacroscopic
neighboring dipoles neighboring dipoles align to form align to form domainsdomains
6 possible domains 6 possible domains per grainper grain
infinite possible infinite possible domains per species domains per species random random orientations orientations no net no net dipole dipole not not piezoelectricpiezoelectric
PolingPoling
strong field appliedstrong field applied field removed – net dipole recedes slightlyfield removed – net dipole recedes slightly not all domains within a grain will switchnot all domains within a grain will switch
P
Poling cont’d- XRDPoling cont’d- XRD
Poled
Tetragonal Rhombohedral
(111)
{111}
{111}(111)
Unpoled
1:31:2
HysteresisHysteresis Initial polarization Initial polarization
(virginal)(virginal) saturation polarizationsaturation polarization remanent polarizationremanent polarization shows a barrier in shows a barrier in
displacement of B-cationdisplacement of B-cation proof of mechanism for proof of mechanism for
piezoelectricitypiezoelectricity application of AC causes application of AC causes
vibrationvibration
Hysteresis curve for Philips PXE 52
Piezoelectricity Piezoelectricity
Direct EffectDirect Effect mechanical strain mechanical strain electrical pulse electrical pulse
Sensors- proportional responseSensors- proportional response force, engine knocking, crash, microphonesforce, engine knocking, crash, microphones
Generators- conversion of energyGenerators- conversion of energy ignitersigniters
Converse EffectConverse Effect electrical pulse electrical pulse mechanical strain mechanical strain
Actuators- proportional responseActuators- proportional response fuel injection valve, speakersfuel injection valve, speakers
Transducers- conversion of energy (high intensity ultrasound)Transducers- conversion of energy (high intensity ultrasound) medical imagingmedical imaging tissue ablationtissue ablation
PMN-PZTPMN-PZT
Pb (Mn,Nb) OPb (Mn,Nb) O33 – Pb (Zr,Ti) O – Pb (Zr,Ti) O33
(soft)(soft) (hard) (hard)
xPMN-(1-x)PZT ceramic systemxPMN-(1-x)PZT ceramic system No “mean value theorem”No “mean value theorem”
EquipmentEquipment
Berlincourt meter- dBerlincourt meter- d3333 tester tester
Pennebaker Model 8000Pennebaker Model 8000 design and operationdesign and operation
SetupSetup
Set ParametersSet Parameters tightness of clamptightness of clamp: 105: 105oo
calibrationcalibration: set for post-: set for post-warmingwarming
interval time (min):interval time (min): 1,5,15,60 for 30 sec.1,5,15,60 for 30 sec.
cooling timecooling time
VariablesVariables warming timewarming time sample thickness, weight, sample thickness, weight,
atmosphere atmosphere
d33 value vs. tightness of brass screw
0
20
40
60
80
100
120
-300 -200 -100 0 100 200 300 400
Degrees of turn from standardd
33 (
pC
/N)
ResultsResultsLiNbO3
No warming
95
100
105
110
115
120
125
0 50 100 150 200
time (min)
d3
3 (
pC
/N)
LiNbO3Warmed 3 hrs.
100
105
110
115
120
125
0 50 100 150 200
Time (min)
d3
3 (
pC
/N)
ResultsResults
LiNbO3warmed 2.5 hours with diff. sample
100
100.5
101101.5
102
102.5
103
103.5104
104.5
105
0 10 20 30 40 50 60 70
time (min.)
d33
(p
C/N
)
ResultsResults
k270-med. Hardno warming
200
250
300
350
400
0 10 20 30 40 50
time (min.)
d33
(p
C/N
)
ResultsResults
k350- soft PZTno warming up
260
270
280
290
300
310
320
0 10 20 30 40 50
time (min.)
d3
3 (
pC
/N)
k700- very soft PZT #1no warming (smaller cooling time)
280
300
320
340
360
380
400
0 10 20 30 40 50
time (min.)
d33 (
pC
/N)
k700- very soft PZT #1 no warming (calib. 3.06)
280
300
320
340
360
380
400
0 10 20 30 40 50
time (min.)
d3
3 (
pC
/N)
ResultsResults
Current TheoryCurrent Theory
Possible ExplanationsPossible Explanations• operator erroroperator error
• reproducedreproduced
• equipment errorequipment error• unknown phenomenonunknown phenomenon
Current TheoryCurrent Theory
Equipment ErrorEquipment Error Values of d33 are significantly lower (up to 50%) of Values of d33 are significantly lower (up to 50%) of
reported values by Keramos.reported values by Keramos. Keramos has noticed the same decrease but not Keramos has noticed the same decrease but not
further investigatedfurther investigated Tests to be conducted at Keramos with 2 different Tests to be conducted at Keramos with 2 different
models of Berlincourt metermodels of Berlincourt meter
Future WorkFuture Work
• Conclude decreasing piezoelectric Conclude decreasing piezoelectric constant due to equipment errorconstant due to equipment error
• Determine cause of the defectDetermine cause of the defect
• Prepare method of obtaining accurate Prepare method of obtaining accurate d33 values with current Pennebaker d33 values with current Pennebaker modelmodel
AcknowledgementsAcknowledgements
Dr. Keith BowmanDr. Keith Bowman Thomas KeyThomas Key Piezo Technologies- Keramos DivisionPiezo Technologies- Keramos Division NSF REU GrantNSF REU Grant