Developing Lead-Free Piezoceramics Lead-Free Piezoceramics ... Ferroelectrics: starting projects ......

Jürgen Rödel | TU Darmstadt | Materials Science – Ceramics Group | 1

Developing Lead-Free

Piezoceramics

Jürgen Rödel

Institute of Materials Science

Technische Universität Darmstadt

Germany


Outline

I. Introduction Ferroelectrics Division (2)

Projects and Teams

II. Lead-Free Piezoceramics (3)

Legislation and History

III. BNT-Based Relaxors (13)

Structure and Electrical Properties

IV. BCT-BZT Based Ceramics (7)

Room Temperature Applications

V. KNN-Based Ceramics (4)

Temperature Stability

VI. Transfer (3)


Ferroelectrics: starting projects – 2003 5 projects ended

B3

Kleebe/Donner

TEM/XRD A1

Rödel

Lead-Free

B7

von Seggern/Klein

Polarization Dynamics

C1

Albe

Defect Structure

C5

Genenko/von Seggern

Charge Transport

D1

Rödel

El. Fatigue

Synthesis Characterization

Modeling

Components

A2

Hoffmann

PZT ended 2010

B1

Eichel/Dinse ended 2010

B2

Balogh ended 2010

B5

Lupascu/Rödel ended 2006

C3

Müller/Becker ended 2010


Ferroelectrics: current projects – 2014 4 new projects started

B3

Kleebe/Donner

TEM/XRD A1

Rödel

Lead-Free B7

von Seggern/Klein

Polarization Dynamics C1

Albe

Defect Structure

C5

Genenko/von Seggern

Charge Transport

D1

Rödel

El. Fatigue

Synthesis Characterization

Modeling

Components C6

Xu

defect /dw

interaction started 2012

B9

Buntkowsky

NMR started 2009

D6

Webber

Mechanics

started 2012

T2

Hoffmann

PbO Stoichiometry started 2011


Legislation

ELV

Lead-containing piezoelectric devices

Category 10 (a)

RoHS II

Lead-containing piezoelectric devices

Category 7

Exemptions expire latest after maximum validity period

5 years (July 2016)

Categories 1-7,10

Continuous process

UNLESS INDUSTRY REQUESTS CONTINUATION!

18 MONTHS PRIOR TO EXPIRY Next revision for INDUSTRY July 2016

EU-Directive 2011/65/EU: RoHS II. Off. J. Eur. Un. 2011;L 174:88 EU-Directive 2000/53/EC: ELV. Off. J. Eur. Un. 2000;L 269:34 //


History of lead-free piezoceramics

1945 BaTiO3

piezo transducer (patent)

mid 1950s PZT ceramics

1945 Poling

process (Gray)

1954 1st report KNN (Shirane et al.)

1959 Piezoelectric data of KNN (Egerton&Dillon)

2004 LF4

composition (Saito et al.)

2004 Improving

the sintering,

e.g. Cu-doping (Matsubara et al.)

2001 EU LEAF project

2003 1st EU legislative

1957 BKT discovery (Popper et al.)

1960 BKT properties (Smolenskii et al.)

1991 BNT-BT (Takenaka et al.)

2007 BNT-BT-KNN (Zhang et al.)

KNN-based BNT-based Other

2009 BCT-BZT (Liu, Ren)

2014 KNN+ Ni electrodes (Liu et al.)

2013 Temperature-insensitive

strain in KNN (Wang et al.)

1996 BNT-BKT (Elkechai et al.)

2009 hard BNT-BT for ultrasonic

cleaners (Tou et al.)

2014 Mn- and Fe-doped BNT-

BKT-BLT (Taghaddos et al.)

2014 BCT-BZT high d33* (Ehmke et al.)


Publications on lead-free piezoceramics

Warwick

Zitierungen in

2013 (von

Veröffentlichungen

aus 2009-2013) 0

200 Anzahl

Veröffentlichungen

2013

5

0

Bordeaux Lausanne

Darmstadt

Ljubljana

29

9

287

454

Karlsruhe

4


BNT-based


BNT-based piezoceramics - projects

A1

Rödel

Synthesis

B3

Kleebe/Donner

TEM/XRD

B7

von Seggern/Klein

Polarization Dynamics

B9

Buntkowsky

NMR

C1

Albe

Defect Structure

C5

Genenko/von Seggern

Charge Transport

C6

Xu

Defect/DW

Interaction

D1

Rödel

Electrical

Fatigue

D6

Webber

Mechanics

atomic

macro-

scopic

length

scale

experiment theory


P(E,T) in BNT-6BT

Ergodic

Relaxor

Nonergodic

Relaxor

Ferroelectric

Long-range

order

TF-R

E

P

E

D1


E-T Diagram in BNT-3BT:Mn D1

Sapper et al., J. Appl. Phys. 115, 194104 (2014)


Fe-modification=hard-doping? D1

expectation:

Ebias up

Pr down

strongly aged:

pinched loop

measurement


23Na MAS NMR –

Local structure of BNT-6BT B9

Pedro Braga-Groszewicz, submitted to PRL

500 250 0 -250 -5000

1000

2000

3000

100000

200000

500 250 0 -250 -5000

1000

2000

3000

100000

200000

Inte

nsity (

arb

. u

nit)

-L (kHz)

Inte

nsity (

arb

. u

nit)

-L (kHz)

CT

ST

Unpoled Poled

Cubic 25.9% 2.1%

Polar 74.1% 97.9%

unpoled

ST

CT= 1.07

ST

CT= 1.5

poled

ST

CT< 1.5

ST

CT= 1.42

non-cubic mixture


Atomic Structure of BNT C1

Gröting et al., Phys. Rev. B. 86, 134118 (2012)

• Zero pressure: BNT is structurally frustrated

• Ab initio calculations suggest the existence of

chemically ordered nanoregions (CNR)

• Matrix: R3c-like CNR: Pbnm-like


Diffuse scattering BNT-4BT single crystal B3

Streaks

→ Random Stacking Faults

Defect:

Stacking Fault

in Tilt Sequence

Stacking Faults are the

Boundaries of PNRs

Streaks: Daniels et al., Appl. Phys. Lett. 98, 252904 (2011)


TEM as f(T) in BNT-6BT-1KNN

Kling et al., J. Am. Ceram. Soc. 96, 3312 (2013)

A1, B3

94BNT-5BT-1KNN


Phase transitions in BNT-6BT: f(σ) A1,(D6)

Webber et al., J. Appl. Phys. 108, 014101 (2010)

• Stress-free XRD:

polar tetragonal P4mm to non-polar

tetragonal P4/mmm at 195°C

• Uniaxial compressive stress:

Field-induced P4/mmm to P4/bm

→oxygen octahedral tilting

→stress induced phase transition

no remanent strain

P4/mmm

P4/bm


BNT-based actuator materials

0 2 4 6 80.0

0.1

0.2

0.3

0.4

0.5

BNBK2:1 MPB

textured KNN (LF4T)

soft PZT

BNT-6BT-2KNN

S (

%)

E (kV/mm)

BNT-18BT-12KNN

BNT-28ST

Jo et al., J. Electroceram. 29, 71-93 (2012)


Relaxor Ferroelectric Composites

matrix

S

E

Susa

Epol

composite

Susa

Epol

• Electric field seed gets poled first propagates polarization to matrix

core gets “easier” poled ≙ polarization at lower fields (Epol )

• Only small amounts of shell required (nuclei of polarization) maintain the

high strain of matrix

Mechanism:

A1, C. Groh

associated

Groh et al., Adv. Funct. Mat. 24, 336-362 (2014)


-6 -4 -2 0 2 4 6

-0.4

-0.2

0.0

0.2

0.4

Pola

rizatio

n (

C/m

2)

Electric field (kV/mm)

RE

FE

@0.05 Hz

0 1 2 3 4 5 60.0

0.1

0.2

0.3

0.4

0.5

FE

FE: Epol

=1.9 kV/mm

RE: Epol

=4.6 kV/mm

Str

ain

(%

)

Electric field (kV/mm)

RE

@0.05Hz

Polarization coupling Strain coupling

Coupling mechanisms

0 20 40 60 80 100100

200

300

400

500

600

700 E

max=6 kV/mm

Emax

=4 kV/mm

d33*(

pm

/V)

FE content (vol.%)0 20 40 60 80 100

100

200

300

400

500

600

700 E

max=6 kV/mm

Emax

=4 kV/mm

d33*(

pm

/V)

FE content (vol.%)

A1, C. Groh

Haibo Zhang (AvH)


BZT-BCT


Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3

Keeble et al., Appl. Phys. Lett. 102, 092903 (2013)

• Qualitative agreement in phase diagram Acosta et al., Acta Mater. 80, 48-55 (2014)

0.30 0.35 0.40 0.45 0.50 0.55 0.60

30

40

50

60

70

80

90

100

T

OR

T (

°C)

BZT-xBCT

C

Extrapolation x=0.36 to 0.5

TR-O

TO-T

Tc

A1, M. Acosta

associated


BZT-xBCT: small signal d33 as f(x, T)

d33 (pC/N)

• Peak at O-T phase transition

• No peaking at triple points

• Applications limited below 95 °C at x=0.6 d33~300 pC/N

A1, M. Acosta

associated

R O

T

C

Acosta et al., Acta Mater. 80, 48-55 (2014)


BZT-xBCT: large signal d33* as f(x, T)

• Peak at R-O and O-T phase transitions

• No peaking at convergence region!

• Low temperature stability limits applications below 90 °C

A1, M. Acosta

associated

Acosta et al., Acta Mater. 80, 48-55 (2014)

O


In-situ E-field studies

BZT-0.32BCT

3.2 kV/cm 4.2 kV/cm 5 kV/cm

virgin

2 kV/cm

2 kV/cm virgin 1.48 kV/cm

H.Guo, X.Tan, Iowa State University, USA

A1, M. Acosta, B3

X. Tan (Iowa State Univ., USA)


Polarization dynamics in BZT-xBCT

Thermodynamic

activation barrier

per unit of volume

Critical volume of

nucleating domain

Activation barrier

Zhukov et al. Appl. Phys. Lett. 103, 152904 (2013)

• Maximized properties due to minimum

in activation barrier for domain

switching

A1, M. Acosta

B7, S. Zhukov

-3 -2 -1 0 1 2 3

-0.20

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0.20

x=0.35

Pola

rization (

C/m

2)

E(kV/mm)

x=0.45 x=0.6


BZT-BCT under

uniaxial compressive stress

M. Ehmke et al., Acta Mater. 78, 37-45 (2014)

BNT-40BCT

• Stress < 50 MPa increasing d33* at low E and T

• Mechanical loading: E stabilizes domains parallel to stress

• Moderate stresses: favour strain

→ E is large enough to reorient ferroelastically switched domains

A1, M. Ehmke

Purdue Univ., USA


KNN-based


Temperature-Insensitive Strain

in modified KNN

0.00

0.04

0.08

0.12

0.16

200o C

175o C

150o C

125o C

100o C

80o C50

o C

40o C

35o C

30o C

Str

ain

(%

)

E (kVmm-1 / scale)

22o C

@4kV/mm

(Li, Ta)-KNN-CaZrO3

S=Q(Pmax2-Pr

2)

300pm/V < d33* < 350pm/V

from RT to 175°C 50 100 150 200

0

100

200

300

400

small signal d33

large signal d*33

Pie

zoele

ctric

const

ant

(pm

/V)

Temperature (oC)

Ke Wang et al., Adv. Funct. Mater. 23, 4079-86 (2013)

Ke Wang (AvH fellow)

Tsinghua Univ., China


MPB in KNN-based ceramics

0

100

200

300

400

500

0

10

20

30

40

50

60

0 0.02 0.04 0.06 0.08

d33(p

C/N

)

k p(%

)

x

0

1000

2000

3000

(R

T)

100

200

300

t (o

C)

R T

J. Zushi, R. Wang et al., Jpn .J. Appl. Phys., 52 (2013)

0.90(Na0.5K0.5)NbO3–xBaZrO3

–(0.10-x)(Bi0.5Li0.5)TiO3

Aim: phase boundary between

tetragonal and rhombohedral

(1-x)(Na0.5K0.5)NbO3–xBaZrO3

• rhombohedral 0.08 ≤ x ≤ 0.15

(RT)

(1-x)(Na0.5K0.5)NbO3–

x(Bi0.5Li0.5)TiO3

• tetragonal 0.06 ≤ x ≤ 0.15

(RT)

Ruiping Wang

(AIST, Tsukuba, Japan)


d33(T) in KNN-based MPB material

0

100

200

300

400

500

600

700

0 50 100 150 200 250 300

d33

at 10 Hz

small signal d33

large signal d*33

Pie

zoele

ctr

ic c

onsta

nt

(pm

/V)

Temperature (oC)

@2kV/mm

MPB composition 9262BBL

R. Wang et al., unpublished

Ruiping Wang

(AIST, Tsukuba, Japan)

0.92(Na0.5K0.5)NbO3-

xBaZrO3-

(0.08-x)(Bi0.5Li0.5)TiO3


Summary:

Innovation management

Legislation trigger

Peak of inflated expectations

Trough of disillusionment

Transfer enlightenment


Worldwide Research Trend

Nature Paper Saito EU-Legislative

Public

ations/E

xpecta

tions


Public

ations/E

xpecta

tions


Pick low-hanging fruits Low-hanging fruits picked

Public

ations/E

xpecta

tions

Deeper Science

(Adv. Fun. Mat, APL)

Application Relevance


Industrial Development

Public

ations/E

xpecta

tions

0 -20 20 10 -10

2010 2020 2030 2000 year

year

High Frequency and

Sensing Applications

• High Power

• Ultrasonic Cleaner

• Knocking Sensor

• Parking Pilot

• Flow Meter

High Reliability

• Fuel Injector


TU Darmstadt:

W. Jo, R. Dittmer, S. Schaab, T. Granzow, J. Glaum, E. Anton, E. Sapper, S. Zhang, J. Chen, E. Aulbach, D.

Isaia, C. Groh, M. Acosta, J. Zang, H. Zhang, J. Kling, L. Schmitt, M. Hinterstein, A. Kleebe, W. Donner, H.

v.Seggern, G. Buntkowsky, P. Braga-Groszewicz, K. Webber. S. Zhukov

Ferroelectrics:

D. Damjanovic (EPFL, Switzerland) X. Tan (Iowa State University, USA (TEM)

BNT-based relaxors:

A.J. Bell (Leeds University, UK) ; J.-S. Lee (Ulsan University, Korea) ; S.J. Jeong (KERI, Korea)

KNN:

K. Wang, J.F. Li (Tsinghua University, Beijing, CH) ; R. Wang, (AIST, Tsukuba, Japan)

BCT-BZT:

M. Ehmke, J. Blendell, (Purdue, USA), K.J. Bowman, (IIT, USA)

Single crystals (BNT-BT):

D. Rytz (FEE, Germany)

Acknowledgements

Developing Lead-Free Piezoceramics Lead-Free Piezoceramics ... Ferroelectrics: starting projects ......

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