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SOLUTION DERIVED LEADSOLUTION DERIVED LEAD-- FREE (BiFREE (Bi0.50.5NaNa0.50.5)TiO)TiO33––BaTiOBaTiO33 (BNBT) (BNBT)
THIN FILMS IN THE PROXIMITY OF THE MORPHOTROPIC PHASE THIN FILMS IN THE PROXIMITY OF THE MORPHOTROPIC PHASE
BOUNDARY (MPB)BOUNDARY (MPB)
M.D. Mezcua, J. Ricote, D.Chateigner1, C. Gutiérrez-Lázaro, I. Bretos, R. Jiménez, R. Sirera2 and
M.L. Calzada
Instituto de Ciencia Instituto de Ciencia
de Materiales de Madridde Materiales de Madrid
M.L. CalzadaInstituto Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC). Cantoblanco. 28049
– Madrid. Spain. 1 Laboratoire de Cristallographie et Sciences des Matériaux (CRISMAT). Ecole Nationale Supérieure d'Ingénieurs de Caen
(ENSICAEN). Université de Caen. 14050 – Caen. France.2 Departamento de Química y Edafología. Facultad de Ciencias. Universidad de Navarra. 31080 – Pamplona, Navarra.
Spain.
1. Index Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
Instituto de Ciencia Instituto de Ciencia
de Materiales de Madridde Materiales de Madrid
1. Objectives
1. Objectives Solution derived lead-free…Solution derived lead-free…
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1. Objectives
• The main goal of this work is the study of
lead-free ferroelectric oxides based on the
(1-x)(Bi0.5Na0.5)TiO3-xBaTiO3 (BNBT) system
to replace the well known Pb(ZrxTi1-x)O3 (PZT)
and the manufacturing of these materials as
thin films for its integration in microelectronic
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
Instituto de Ciencia Instituto de Ciencia
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thin films for its integration in microelectronic
devices.
Lead-free compositions to substitute lead based- on compositions (PZT)
1. Objectives Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
Instituto de Ciencia Instituto de Ciencia
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Preparation of thin
films
Integration of ferroelectric
materials in the
information technologies
(ITRS 2011)
Actual trends on the
manufacturing of thin films
2. Introduction
2.Introduction Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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2. Introducción
MPB
Solution derived lead-free…Solution derived lead-free…
BNT-BT
Phase diagram
(1-x)(Bi0.5Na0.5)TiO3-xBaTiO3 (BNBT) Solid solution
Morphotropic phase
boundary(MPB)
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Thomas et al. Solid State Sci 2008; 10:934-940
MPB
Takenaka et al. Jpn J Appl Phys 1991; 30: 2236-39
2. Introduction
Bulkceramics
Thin platesThickfilms
Thin filmsUltra- thinfilms
Nano-sozedsystems
1950
100 µm 10 µm 1 µm 100 nm 1 nm1 mm
1970 1990 >2000
Towards the miniaturization of ferroelectric materials and
their integration into microelectronic devices
High permitivity
DRAMs
Electro-optic activity
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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Piezoelectricity
Pyroelectricity Ferroelectricity
NVFRAMs
Infrared sensor Sensors Actuators
Ferroelectricfilms
Bretos. Ph. D Thesis UAM 2006
2. Introduction
773-813 K528-673K
Rhombohedralphase
Tetragonal phase
Cubic phase
Bulk ceramic
Bi0.5Na0.5TiO3
Increasing temperature
RhombohedralRhombohedralTetragonalTetragonal
Thomas et al.Solid State Science 2010; 12: 311-17
Solution derived lead-free…Solution derived lead-free…
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Bi0.5Na0.5TiO3
0.89Bi0.5Na0.5TiO3-0.11BaTiO3
Single-crystal
X-ray
diffraction
Rhombohedral phasewith tetragonal
inclusions
Tetragonal
TetragonalTetragonal
0.90Bi0.5Na0.5TiO3-0.10BaTiO3
Thin film
Jones et al. Acta Crystallogr B 2000; B56:426-30Jones et al. Acta Crystallogr B 2002; B58:168-78
Cheng et al. Appl Phys Lett 2004; 85: 2319-21
Bretos et al. Mater Lett 2011; 65:2714-2716
Thomas et al.Solid State Science 2010; 12: 311-17
Displacement of the MPB composition
Structural effectsThe reason
could be
3. Experimental Procedure
3. Experimental procedure Solution derived lead-free…Solution derived lead-free…
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CH3COOH + OH(CH2)3OH + H2O
MetallicMetallic precursorprecursorSolventsSolvents
Molar ratios
1.0:10.0 f Ti (IV) to
any solvents
10.0 mol% of Bi(III) excess +
10.0 mol% of Na(I) excess
Reflux in air for 8h
Na(OCOCH3).3H2O + Bi(OCOCH3)3 +
Ti(CH3COCHCOCH3)2(OC3H7)2
Bi0.5Na0.5TiO3
Precursor sol
CH3CH2COOH + (CH3CH2CO)2OBaCO3
C4H9OH + CH 3COCH2COCH3
Reflux in air for 2 hStirring at room
temperature
Stirring at room
temperature
C4H9OH
MetallicMetallic precursorprecursor MetallicMetallic precursorprecursorSolventsSolvents SolventsSolvents
SolventsSolvents
BaTiO3
Precursor solution
Ti(OC4H10)
3. Experimental procedure Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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Precursor sol(≈0.60 mol L-1)
Precursor solution(≈ 0.30 mol L-1)
Bi0.5Na0.5TiO3-BaTiO3
Precursor solution(≈ 0.60 mol L-1)
C2H5OH
SolventSolvent
Bi0.5Na0.5TiO3-BaTiO3
Precursor solution(≈ 0.20 mol L-1)
Hoffmann el al. J Eur Ceram Soci 1999: 19 ;1339-1343Alonso et al. J Am Ceram Soci 2008; 92 [10]: 2218-25
Bi0.5Na0.5TiO3
Precursor sol(10%mol.exc. Bi2O3+10% mol. exc. NaO)
Bi0.5Na0.5TiO3
Precursor sol(BNTs)
BaTiO3
Precursor solution(BT)
Stirring at room
temperature(72 h)
Composition in the vicinity of the MPB
3. Experimental procedure
BNBTs10.0
BNBTs5.5BNBTs6.5BNBTs8.0
BNBTs10.0
BNBT5.5BNBT10.0BNBT15.0
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
Stoichiometric 10% mol. Bi(III) and Na(I) excesses
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Crystallinepowders
Diluted solution toprepare the films by
CSD
Dried ethanolAnnealed at900ºC(1h)
Heat shock
Slowcooling
Crystallization: RTP Schwartz Cr Chim 2004; 7 :433-461
25ºC/ 60s
Vacuum
25ºC/ 120s
Oxygen
22s
650ºC/60s
22s100ºC
Refrigeration
Stoichiometric 10% mol. Bi(III) and Na(I) excesses
4. Results and discussion
4. Results and discussion Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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4.1 Crystalline powders
4. Results and discussion Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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Structural analysis by XRDof the powders
Nominal composition
StoichiometricExcesses of
NaO and Bi2O3
For different molar
4. Results and discussion Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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For different molar
ratios of BNT/BTNear to
Coexistence of these structures
Tetragonal Rhombohedral
Morphotropic
phase boundary(MPB)
Takenaka et al. Jpn J Appl Phys 1991; 30: 2236-39
(111)T
(001)T
(100)T
(101)T
(110)T
(002)T
(200)T
(112)T
(211)T
39.3 39.6 39.9 40.2 40.5
(111)T
Inte
nsity (
a.u
.)
2θ(º)
(003
)R
(02
1)Ra)
46.0 46.5 47.0
In
ten
sity (
a.u
.)
2θ(º)
(002)T
(200)T
(202)R
b)
4. Results and discussion
Structural analysis of the crystalline phase in the stoichiometric powders with
different BNT/BT molar ratios
Step used 0.005º/5s Step used 0.005º/5s
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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20 30 40 50 60
*
* *
* *
*
*
*
(202)R
(111)T
(110)R
BNBTs10.0
BNBTs8.0
BNBTs6.5
Inte
nsity (
a.u
.)
2θ(º)
BNBTs5.5
(101)R
(001)T
(100)T
(012)R
(021)R
(003)R
(002)T
(200)T
(102)T
(201)T
(210)T
(113)R
(211)R
(112)T
(211)T
(104)R
(122)R
*
*
Step used 0.05º/3s
Step used 0.005º/5s Step used 0.005º/5s
Jones et al. Acta Crystallogr B 2000; B56:426-30
Jones et al. Acta Crystallogr B 2002; B58:168-78
JCPDS:36-0640(Rhombohedral
Bi0.5Na0.5TiO3)05-0626(Tetragonal
BaTiO3)
(00
3)R
(02
1)R
(11
1)T
BNBTs6.5Inte
nsity (
a.u
.) BNBTs8.0
a)
46.0 46.5 47.0
Inte
nsity (
a.u
.)
2θ (º)
BNBTs6.5
BNBTs8.0
(200)T
(202)R
(002)T
b)
4. Results and discussion
Structural analysis of crystalline stoichiometric powders fordifferent BNT/BT molar ratios
Deconvolution has been made using program V1-40 and the peaks have been fitted to seudo-voigt 2 function
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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SAMPLESMOLAR RATIOS
BNT/ BT
NOMINAL COMPOSITION
(stoichiometric)
CRYSTALLINE STRUCTURES
OBTAINED FROM XRD
PATTERNS
BNBTs5.5 94.5/5.5 (Bi0.5Na0.5)0.945Ba0.055TiO3 Rhombohedral
BNBTs6.5 93.5/6.5 (Bi0.5Na0.5)0.935Ba0.065TiO3
Rhombohedral + tetragonal
(MPB)
BNBTs8.0 92.0/8.0 (Bi0.5Na0.5)0.920Ba0.080TiO3
Rombohedral + tetragonal
(MPB)
BNBTs10.0 90.0/10.0 (Bi0.5Na0.5)0.900Ba0.100TiO3 Tetragonal
39.5 40.0 40.52θ (º)46.0 46.5 47.02θ (º)
(001)T
(100)T
(101
)T
(110)T
(111
)T
(00
2)T
(200)T
(112)T
(211)T
39.2 39.6 40.1 40.5 41.0
(111)T
2θ(º)
Inte
nsity (
a.u
.)
(003)R
(021)R
a)
45.2 45.6 46.0 46.4 46.8 47.2
(20
2)R
Inte
nsity (
a.u
.)
2θ
(00
2)T (2
00)T
b)
4. Results and discussion
Structural analysis of the crystalline powders containing excesses of Na(I) and Bi(III)
Step used 0.005º/5sStep used 0.005º/5s
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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20 30 40 50 60
(211)R
(113)R
BNBT15.0
BNBT10.0
2θ(º)
Inte
nsity (
a.u
.)
BNBT5.5
(101
)R
(001)T
(100)T
(012)R
(11
0)R
(111
)T(0
03)R
(021
)R
(00
2)T
(200)T
(202)R
(102
)T(2
01
)T
(210)T (1
12)T
(211)T
(104
)R
(122)R
*
Step used 0.05º/3s
Step used 0.005º/5sStep used 0.005º/5s
Jones et al. Acta Crystallogr B 2000; B56:426-30
Jones et al. Acta Crystallogr B 2002; B58:168-78
JCPDS:36-0640(Rhombohedral
Bi0.5Na0.5TiO3)05-0626(Tetragonal
BaTiO3)
4. Results and discussion
Structural analysis of crystalline powders with excesses of Na(I) and Bi(III) for different BNT/BT molar ratios
39.2 39.6 39.9 40.3 40.6 41.0
(02
1)R
(00
3)R
(111
)T
Inte
nsity (
a.u
.)
BNBT10.0
a)
45.2 45.6 46.0 46.4 46.8 47.2
(20
2)R
(20
0)T
(00
2)T
BNBT10.0
Inte
nsity (
a.u
.)
b)
Deconvolution has been made using program V1-40 and the peaks have been fitted to seudo-voigt 2 function
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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SAMPLEMOLAR RATIOS
BNBT/BT
NOMINAL COMPOSITION
(10%molar exceso Bi2O3+
10%molar exceso NaO)
CRYSTALLINE STRUCTURE
OBTAINED FROM XRD
PATTERNS
BNBT5.5 94.5/5.5 (Bi0.5Na0.5)0.945Ba0.055TiO3 Rhombohedral
BNBT10.0 90.0/10.0 (Bi0.5Na0.5)0.900Ba0.100TiO3
Rhombohedral+ tetragonal
(MPB)
BNBT15.0 85.0/15.0 (Bi0.5Na0.5)0.850Ba0.150TiO3 Tetragonal
39.2 39.6 39.9 40.3 40.6 41.02θ(º)
45.2 45.6 46.0 46.4 46.8 47.2
2θ(º)
200
250
300
350
400
Te
mp
era
ture
(ºC
)
4. Results and discussion
Determination of the morphotropic phase boundary(MPB) for the crystalline powders
Stoichiometric nominal compositionNominal composition
containing excesses of Na(I) +Bi(III)
200
250
300
350
400
Te
mp
era
ture
(ºC
)
Cubic
Tetragonal
Cubic
Tetragonal
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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0 5 10 15 20 25 300
50
100
150
200
Te
mp
era
ture
(ºC
)
(Bi0.5
Na0.5
)1-x
BaxTiO
3 (mol%)
Rout et al. J Ceram Soc Jpn 2009; 117 [7]: 797-800
0 5 10 15 20 25 300
50
100
150
200
Te
mp
era
ture
(ºC
)
(Bi0.5
Na0.5
)1-x
BaxTiO
3 (mol%)
Tetragonal
Rhomboedral
MPB
Tetragonal
Rhombohedral
MPB
4.2 Thin films
4. Results and discussion Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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Ferroelectric system in thin film form:
•Lost by volatilization of Na(I)+Bi(III)
•Change of the phase because of
structural effects induced by the
substrate
(11
1)
Pt
(20
0)
Pt
(20
0)
Pe
rovskite
Pe
rovskite
Pe
rovskite Pt(
11
1)
Pt
(11
1)
Pe
rovskite
Inte
nsity (
a.u
.)32.0 32.3 32.5 32.8 33.0
Pe
rovskite
R
Pe
rovskite
T
Inte
nsity (
a.u
.)
2θ (º)
4. Results and discussion
XRD patterns of BNBTs thin films without
excesses of any metallic precursor
Step used 0.005º/5s
Reflections from the
substrate
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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Kβ P
t (1
11)
20 25 30 35 40 45 50
Pt
(20
0)
Pe
rovskite
Pe
rovskite
Bi xP
t (1
11
)
Pe
rovskite
Inte
nsity (
a.u
.)
BNBTs5.5
BNBTs6.5
BNBTs8.0
BNBTs10.0
2θ(º)
Step used 0.05º/3s
Ba2+ has been
incorporated into
the structure
4. Results and discussion
Pt
(20
0)
Pe
rovskite
Pe
rovskite
Pe
rovskite
Pt(
11
1)
Pe
rovskite
Inte
nsity(a
.u.)
Pt
(111)
Pt(
111)
32.0 32.3 32.5 32.8 33.0
In
ten
sity (
a.u
.)
2θ(º)
Pero
vskite T
Pero
vskite R
XRD patterns of BNBT thin films with
addition of Na(I) and Bi(III) excesses in the
nominal composition
Step used 0.005º/5s
Reflections from the
substrate
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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20 25 30 35 40 45 50
Pe
rovskite
BNBT15.0
BNBT10.0
Inte
nsity(a
.u.)
2θ(º)
BNBT5.5K
βP
t (1
11)
Bi xP
t(1
11)
Step used 0.05º/3s
Ba2+ has been
incorporated into
the structure
4. Results and discussion
-600 -400 -200 0 200 400 600
0
20
40
60
P(µC/cm2)
E (kV/cm)
BNBTs5.5
BNBTs6.5
BNBTs8.0BNBTs10.0
Electrical measurement of BNBTs
nominal stoichiometric thin films
Cross-section and plan-view images of
BNBTs nominal stoichiometric films
2µm
2µm2µm
2µm
BNBTs5.5
BNBTs6.5
Solution derived lead-free…Solution derived lead-free…
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-60
-40
-20E (kV/cm)
2µm
2µm 2µm
2µm
2µm
Sample BNBTs5.5 BNBTs6.5 BNBTs8.0 BNBTs10.0
Grain size ≈288 nm ≈194 nm ≈179 nm ≈119 nm
Thickness ≈341 nm ≈459 nm ≈329 nm ≈435 nm
BNBTs6.5
BNBTs8.0
BNBTs10.0
-400 -200 0 200 400
0
30
60
BNBT15.0
BNBT10.0
BNBT5.5
P(µC/cm2)
4. Results and discussion
Electrical measurement of BNBT thin films with
Na(I)+Bi(III) excesses in the nominal composition
Cross-section and plan-view images of
BNBT films containing excesses of
Na(I)+Bi(III) in the nominal composition
2µm2µm BNBT5.5
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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-400 -200 0 200 400
-60
-30
E (kV/cm)
Sample BNBT5.5 BNBT10.0 BNBT15.0
Grain size ≈153 nm ≈170 nm ≈97 nm
Thickness ≈559 nm ≈553 nm ≈550 nm
2µm
2µm2µm
2µmBNBT10.0
BNBT15.0
4. Results and discussion
20
40
60
P(µC/cm2)
BNBT10.0
BNBTs5.5
Electrical measurements comparison between the best
stoichiometric and the best not stoichiometric films
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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-600 -400 -200 0 200 400 600
-80
-60
-40
-20
0
E(kV/cm)
5. Conclusions
5. Conclusions Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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5. Conclusions
•The morphotropic phase boundary (MPB) of BNBT powders has
been situated for 93.5/6.5 and 92.0/8.0 ‘stoichiometric’ nominal
composition. Addition of Na(I) and Bi(III) excesses to the system leadsto a shift of the MPB for these powders to the 90.0/10.0 nominal
composition.
•The best ferroelectric response for BNBT films has been obtainedfor the 90.0/10.0 composition with addition of Na(I) and Bi(III)
Solution derived lead-free BNBT thin films Solution derived lead-free BNBT thin films
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for the 90.0/10.0 composition with addition of Na(I) and Bi(III)
excesses to the respective precursor solution (Pr 23 µC/cm2 andPs≈60 µC/cm2), the composition for which has identified the MPB in
the crystalline powders.
•Studies are in progress to elucidate the either intrinsic (e.g.
compositional effects) or extrinsic (e.g. scaling effects) driving nature
of the boundary displacement observed in these BNBT films withrespect to bulk counterparts.
SOLUTION DERIVED LEADSOLUTION DERIVED LEAD-- FREE (BiFREE (Bi0.50.5NaNa0.50.5)TiO)TiO33––BaTiOBaTiO33 (BNBT) (BNBT)
THIN FILMS IN THE PROXIMITY OF THE MORPHOTROPIC PHASE THIN FILMS IN THE PROXIMITY OF THE MORPHOTROPIC PHASE
BOUNDARY (MPB)BOUNDARY (MPB)
M.D. Mezcua, J. Ricote, D.Chateigner1, C. Gutiérrez-Lázaro, I. Bretos, R. Jiménez, R. Sirera2 and
M.L. Calzada
Instituto de Ciencia Instituto de Ciencia
de Materiales de Madridde Materiales de Madrid
M.L. CalzadaInstituto Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC). Cantoblanco. 28049
– Madrid. Spain. 1 Laboratoire de Cristallographie et Sciences des Matériaux (CRISMAT). Ecole Nationale Supérieure d'Ingénieurs de Caen
(ENSICAEN). Université de Caen. 14050 – Caen. France.2 Departamento de Química y Edafología. Facultad de Ciencias. Universidad de Navarra. 31080 – Pamplona, Navarra.
Spain.