JSI
Ferroelectrics: Towards Smaller Dimensions
and Complex Structure
Marija Kosec
Jožef Stefan Institute
Jamova 39
1000 Ljubljana
Slovenija
marija.kosec@ijs.si
Bio-Nano-Space-12-03 -2008
JSI
Electronic Ceramics Department, K-5
Head: Prof. Dr. Marija Kosec
Staff: 20: 5 PhD, 4 Post-doc, 8 PhD students,
2 ing, 1 technician + part–time:
Research Activities
Materials:
 Piezoelectrics:Pb(Zr,Ti)O3 (PZT),
 Relaksors: Pb (Mg1/3Nb2/3)O3 - PbTiO3 (PMN-PT),
 Lead free piezoelectrics:(K,Na)NbO3 (KNN),
 Tunable ferroelectrics: (Ba, Sr)TiO3 K(Nb,Ta)O3,
 Dielectrics: CuCa3Ti4O12 (CCTO)
 Oxide conductors: (La,Sr)CoO3 (LSCO), La-ruthenates,
 Multiferoic: BiFeO3 ( BaO, PbO), LaMnO3,
 ZnO
Bio-Nano-Space-12-03 -2008
JSI
Processing: How to get extrem: properties,
design, size….
Nano-powders:
sol-gel synthesis (PZT)
mechanically activated synthesis (PMN-PT, KNbO3, NaNbO3,KNN)
Thin films by Chemical Solution Deposition (CSD)
(PZT, PMN-PT, KNN, KNT, BST,CCTO)
Thick film:
Screen printing (PZT, PMN-PT, KNN)
Electrophoresis (PZT)
Ink-jet printing (ZnO)
Bulk (KNN), Single crystal: KNN
Devices: C-MEMS
Medical transducers
Pressure sensors
Bio-Nano-Space-12-03 -2008
JSI
Ferroelectric ceramic
materials
Pr
Ec
E (V/m)
Ferroelectric and
dielectric
2
-3
S (10 )
P (C/cm )
Piezoelectric
E (kV/cm)
0
0.30
A: Pb
B: Ti,Zr
0.28
Tunable
o
900 C
C (pF)
0.26
0.24
0.22
Polar structur,
Electric dipols
0.20
o
0.18
700 C
-200 -150 -100
Bio-Nano-Space-12-03 -2008
-50
0
U (V)
50
100
150
200
JSI
Feroelectric ceramics: Composition
B
BaTiO3
PbTiO3 (PT)
Pb(Zr,Ti)O3 (PZT), (Pb,La)(Zr,Ti)O3 (PLZT)
Pb(Mg1/3Nb2/3)O3 (PMN)
Pb(Mg1/3Nb2/3)O3 – PbTiO3 (PMN-PT)
Pb(Zn1/3Nb2/3)O3 – PbTiO3 (PZN-PT), (PMN-PZN-PT)
PbSc1/2Ta 1/2 O3
high lead content (~60w%) 
problems
ecological
Since last ten years: searching for lead
free materials
Bio-Nano-Space-12-03 -2008
A O
lead-free ferroelectric materials:
JSI
Sodium potassium niobate (K,Na)NbO3 s.s. (KNN).
KNbO3-NaNbO3 phase diagram
The best piezoelectric response
for the compositions close to
the MPB:KNN50/50

TD

4.2
94.4
450
KNN-Sr 4.2
96.0
KNN
PbNb2O6 5.6
tan
d33(pC/N) kp
kt
0.06
70
0.25
0.4
500
0.04
90
0.27
0.5
220
0.02
100
0.34
B.Malič, J.Bernard, J.Holc, D.Jenko, M.Kosec, J.Eur.Cer.Soc.,(2005) 2707
Bio-Nano-Space-12-03 -2008
Bulk: mm, cm range
JSI
Ferroelectrics: Towards
Smaller Dimensions
and Complex Structure
Courtesy of Ferroperm
Piezoceramics S/A
Thick films >1m
Thin films < 1m
100 nm
100 nm
Cross-section SEM of 32Mbit NFRAM,
from: H.S.Joo, Integr. Ferroel., 48(2002), 119.
Bio-Nano-Space-12-03 -2008
JSI
Thick film processing
powder synthesis:
Tem.
PbO+ZrO2+TiO2
Pb(Zr,Ti)O3)
Chem.reactions
crytical
Shaping
clamping
Firing
Thick film
Bio-Nano-Space-12-03 -2008
Thick films >1m
JSI
Thick film procesing
Powder synth.
shaping
screen printing
ink jet printing
electrophoretic deposition
firing
S queegee
M a sk
thick film
P a s te
S c re e n
S u b s tra te
Bio-Nano-Space-12-03 -2008
JSI
modeling
3,0E-05
Maximum deflection [m]
1
2,5E-05
1
Cantilever
2
2,0E-05
3
1,0E-05
Diaphragm
Linear
(Bridge)
Linear
(Cantilever)
Linear
(Diaphragm)
1,5E-05
5,0E-06
Bridge
O p to -e el c tron ci
F bi re op tci cab el
con tro lel r
V
O p tci a lsen so r
hea d
2
0,0E+00
0,0E+00
3
B
A
5,0E+03
1,0E+04
1,5E+04
Pressure [Pa]
Bio-Nano-Space-12-03 -2008
Marina Santo
JSI
LTCC/Au/PZT/ Au
LTCC/PZT barriere/
Au/PZT/Au
Microstructure after firing 1h 850oC.
Bio-Nano-Space-12-03 -2008
JSI
displacement
Displacement ATP05_LTCC
6
Tip displacement [um]
5
4
200V=3µm
3
AV5L-M1++
AV5L-M1+AV5L-M1++2
AV5L-M1+-2
2
1
0
0
100
200
300
400
500
Voltage [V]
dimensions 12.0 × 4.0 × 0.22 mm - 40µm thick PZT
Bio-Nano-Space-12-03 -2008
Bulk: mm, cm range
JSI
Courtesy of Ferroperm
Piezoceramics S/A
Thick films >1m
Thin films < 1m
100 nm
100 nm
Cross-section SEM of 32Mbit NFRAM,
from: H.S.Joo, Integr. Ferroel., 48(2002), 119.
Bio-Nano-Space-12-03 -2008
Chemical Solution Deposition (CSD) of
Pb(Zr,Ti)O3
PZT
Synthesis
Solutionprecursor:Pb,Zr,Ti
Spinnig
substrate
wet film
Drying, 200 C
dry film
Pyrolysis, 350 C
substrate
substrate
dense, amorphous
film
Crystallization, 600 C
Bio-Nano-Space-12-03 -2008
substrate
dense, crystalline
film
JSI
Synthesis of PZT solution precursor
2-methoxyethanol method
CH3-O-C2H4-OH
O CH2
n-1(RO)
M
O CH2
R
Turova, Turevskaya, Kessler, Yanovskaya, 2002.
Bio-Nano-Space-12-03 -2008
JSI
Pb(OAc)2+x Zr(O R)4 +(1-x) Ti(O R)4
+
CH3-O-C2H4-OH

Reflux
destilation

PZT-solution (sol)

spinning Pt/Si –substrat

drying@ 200oC

pyrolysis@ 350oC

crystallization@ 600oC

PZT thin film
Budd, Dey, Payne , 1985
JSI
Pb(OAc)2 / PbO +
Zr(n-OBu)4
Ti(n-OBu)4
Substrate
100 nm Pt/ 10 nm TiO2/SiOx/Si
CH3-O-CH2CH2-OH
4x
Dissolution
Reflux (2 h)
Distillation
Spin-coating

Drying, 200 oC, 2 min

Heating, 400 oC
(hot-plate)

Sol (CM=0,5)
Single-step
1×(400 oC, 30 min)
1×(400 oC, 60 min)
Multi-step
Excess of PbO: 10 mole %
Bio-Nano-Space-12-03 -2008
4×(400 oC, 5 min)
4x
JSI
Design of microstructure by the constant orientation gives a unique
possibilities to study microstructure-properties relationship
4x200/2 + 400/30
60
2
P (C/cm )
40
100 nm
Pt
Columnar microstructure
Int. (A. u.)
P
<111>
25
30
*
35
-10
0
-20
4x(200/2 + 400/5)
20
4x(200/2 + 400/5)
0
-20
4x200/2 + 400/30
Si
20
-40
40
45
2 (Deg.)
Orientation:constant
10
20
E (V)
Equiaxed grains
100 nm
50
-60
Properties microstructure
M. Mandeljc, M. Kosec, B. Malič, Z. Samardžija, Integrated Ferroelectrics, 30 (2000), 149.
M. Mandeljc, M. Kosec, B. Malič, Z. Samardžija, Integrated Ferroelectries, 41 (2001), 163.
Bio-Nano-Space-12-03 -2008
Ec/(kV/cm)
2
Pr/(C/cm )
35
25
20
Bio-Nano-Space-12-03 -2008
Z
zu
(
lta 111
ti )
H
ZT
Temperatura, T/ C
o
Tem.(oC)
PZT 35/65, (111)
Kim 1995
PZT 40/60, ?
Lefevre 1996
ua 30/
ng 70
19 , (1
99 11
)
P
PZT 40/60, ? n T 3
aš 0
Maki 2002
i r /70
e
,
30
P
JSI
15
10
150
125
100
75
50
25
400
450
500
550
600
650
700
400
450
500
550
600
650
700
JSI
Design of orientation by lead source
Pt
(111)
(111)
Intensity (Arb. units)
?
(100)
Si
(200)
PbO
PbAc
20
25
30
35
40
45
50
2 (Deg.)
XRD spectra of PZT 30/70 films: effect of lead-source, 4 x (200oC, 2
min.+ 400oC, 5 min.)
Bio-Nano-Space-12-03 -2008
JSI
Crystallization mechanism
400oC
1-15 min
Bio-Nano-Space-12-03 -2008
Crystallization mechanism
How can be formed?
From Pb in Pt!
Pb?
From PbO in PZT
How?
Reduction?
How?
Oxidation of organic
C+O2= CO2
2H2+ O2 =2 H2O
Important: amorphous
phase must contain
enough organic.
It is provide by the
choice of precursors.
Bio-Nano-Space-12-03 -2008
JSI
JSI
Reflect Array antenna
2
1
Sourc e
and /or
Rec eiver
top surface
of the plane
0.30
0.28
o
900 C
C (pF)
0.26
0.24
0.22
0.20
o
0.18
700 C
-200 -150 -100
-50
0
U (V)
Unit cell of
radiating element
Waveguide
with metal iris
Phase shifting components
RETINA: Reliable, tuneable and inexpensive antennas by collective fabrication processes,
EU, 6th FP, Thematic priority: Aeronautics and Space
Bio-Nano-Space-12-03 -2008
EADS (D) TAS (F) IMEC (B) EPFL (CH) COV (F) ESIEE (F) JSI (SI) HYB (SI)
50
100
150
200
JSI
BST 30/70
Compositions with a higher Ba-content
At RT:
DIELECTRIC CONSTANT
-Higher permittivity for
solid solutions with a
higher Ba/Sr ratio but
also a higher
T-dependence of .
-Expected: higher
tunability
Temperature dependence of permittivity for BST ceramics
Bio-Nano-Space-12-03 -2008
Tagantsev et al., J. Electroceramics, 2003
Ba0.3Sr0.7TiO3 (BST)
Ba-acetate + Sr-acetate
0.30 Ba (CH3COO)2 +0.70 Sr(CH3COO)2
Dissolved in acetic acid (100 %), R.T.
CH3COOH
+
Ti n-propoxide
Ti(OC3H7)4
Dissolved in 2-methoxyethanol, R.T., inert atmospere
CH3-O-CH2CH2OH

Mixing at 60oC, inert atmospere

BST-precursor solution (0.25M, 0.4 M)
Alumina substrate (25.4 x 25.4 mm2)
polished, 99.6 %, ε ≈ 9.8)
Bio-Nano-Space-12-03 -2008
Spinning
Pyrolysis
Crystallization
JSI
Materials characterization:
JSI
Phase composition: XRD (CuKa)
Microstructure: AFM, FE-SEM
Grain size: lineal intercept (~ 100 grains)
Dielectric characterization:
Air-gapped capacitors (0.75 x 1.5 mm2)
Cr/Au electrodes by lift-off photolithography
C (V): 0V+200V0V−200V0V at 1 MHz (JSI)
and 8 GHz (V. Cherman, EPFL)
Gap (2-10 m)
Au/Cr electrode
BST film
Alumina substrate
Bio-Nano-Space-12-03 -2008
Vendik model
Substrate:
25.4 mm x 25.4 mm
JSI
Microstructure: effect of annealing conditions
900 °C, 15 min.
700 °C, 15 min.
Grain size:
70 nm
T increases
100 nm
100 nm
700 °C, 60 min.
Grain size:
40–45nm
900 °C, 60 min.
Grain size:
80 nm
900 °C, 60 min.
700 °C, 60 min.
100 nm
100 nm
FE-SEM images of BST films on alumina annealed at 700 and 900 °C.
Bio-Nano-Space-12-03 -2008
JSI
0.30
900oC
0.28
o
900 C
 = 722 ± 50
n = 1.93
0.26
C (pF)
100 nm
0.24
0.22
700oC
0.20
100 nm
 = 345 ± 35
n = 1.49
o
0.18
700 C
-200 -150 -100
-50
0
50
100
150
U (V)
C-V response of BST film on alumina annealed at 700 °C
and 900 oC for 60 min. 1MHz, RT, gap width: 8.5 ± 1 m.
Left: surface microstructures of BST films.
Bio-Nano-Space-12-03 -2008
200
Thanks
Dr. Barbara Malič
Dr. Janez Holc
Dr.Marko Hrovat
Dr.Danjela Kuščer-Hrovatin
Dr.Andreja Benčan
Dr. Tadej Rojac
Dipl. ing.Silvo Drnovšek
Dipl. ing.Jena Cilenšek
Ing. Srečko Maček
Darko Belavič, dipl. ing
Dr. Marina Santo- Zarnik
Dr. Mišo Vukadinović
Mitja Jerlah
Dr. Goran Dražič
Dr.Stojan Stavber
Dr. Vid Bobnar
Prof. Adrijan Levstik
Bio-Nano-Space-12-03 -2008
JSI
Prof. Nava Setter, EPFL,Lausanne
Prof. Rainer Waser, RWTH Aachen
Mrs. Wanda Wolny, Ferroperm Piezoceramics,
Copenhagen
ARRS,
EU:LEAF, MINUET, MIND, RETINA
Thank to you!