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Ferroelectrics: Towards Smaller Dimensions and Complex Structure

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1 Ferroelectrics: Towards Smaller Dimensions and Complex Structure
Marija Kosec Jožef Stefan Institute Jamova 39 1000 Ljubljana Slovenija Bio-Nano-Space

2 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

3 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

4 A: Pb B: Ti,Zr Ferroelectric ceramic materials Polar structur,
Ferroelectric and dielectric Piezoelectric A: Pb B: Ti,Zr Tunable Polar structur, Electric dipols Bio-Nano-Space

5 A O B Feroelectric ceramics: Composition 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%)  ecological problems Since last ten years: searching for lead free materials Bio-Nano-Space

6 lead-free ferroelectric materials:
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 B.Malič, J.Bernard, J.Holc, D.Jenko, M.Kosec, J.Eur.Cer.Soc.,(2005) 2707 Bio-Nano-Space

7 Bulk: mm, cm range Thick films >1mm Thin films < 1mm
Ferroelectrics: Towards Smaller Dimensions and Complex Structure Courtesy of Ferroperm Piezoceramics S/A Thick films >1mm Thin films < 1mm 100 nm 100 nm Cross-section SEM of 32Mbit NFRAM, from: H.S.Joo, Integr. Ferroel., 48(2002), 119. Bio-Nano-Space

8 PbO+ZrO2+TiO2 Pb(Zr,Ti)O3) Chem.reactions crytical Shaping clamping
Thick film processing powder synthesis: Tem. PbO+ZrO2+TiO Pb(Zr,Ti)O3) Chem.reactions crytical Shaping clamping Firing Thick films >1mm Thick film Bio-Nano-Space

9 Thick film procesing Powder synth. shaping firing thick film
screen printing ink jet printing electrophoretic deposition Bio-Nano-Space

10 modeling 1 2 3 Bio-Nano-Space Marina Santo

11 Microstructure after firing 1h 850oC.
LTCC/Au/PZT/ Au LTCC/PZT barriere/ Au/PZT/Au Microstructure after firing 1h 850oC. Bio-Nano-Space

12 displacement 200V=3µm dimensions 12.0 × 4.0 × 0.22 mm - 40µm thick PZT
Bio-Nano-Space

13 Bulk: mm, cm range Thick films >1mm Thin films < 1mm
Courtesy of Ferroperm Piezoceramics S/A Thick films >1mm Thin films < 1mm 100 nm 100 nm Cross-section SEM of 32Mbit NFRAM, from: H.S.Joo, Integr. Ferroel., 48(2002), 119. Bio-Nano-Space

14 Chemical Solution Deposition (CSD) of Pb(Zr,Ti)O3
PZT Synthesis Solution- precursor:Pb,Zr,Ti Spinnig wet film substrate Drying, 200 C dry film substrate Pyrolysis, 350 C dense, amorphous film substrate Crystallization, 600 C dense, crystalline film Bio-Nano-Space substrate

15 Synthesis of PZT solution precursor
2-methoxyethanol method 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 200oC 350oC 600oC PZT thin film CH3-O-C2H4-OH O CH2 M R n-1(RO) Turova, Turevskaya, Kessler, Yanovskaya, 2002. Bio-Nano-Space Budd, Dey, Payne , 1985

16 Sol (CM=0,5) Zr(n-OBu)4 Ti(n-OBu)4 Pb(OAc)2 / PbO + CH3-O-CH2CH2-OH
Excess of PbO: 10 mole % Dissolution Reflux (2 h) Distillation Sol (CM=0,5) Zr(n-OBu)4 Ti(n-OBu)4 Pb(OAc)2 / PbO + CH3-O-CH2CH2-OH Spin-coating Drying, 200 oC, 2 min Heating, 400 oC (hot-plate) Substrate 100 nm Pt/ 10 nm TiO2/SiOx/Si 4x 4x 1×(400 oC, 30 min) 1×(400 oC, 60 min) Single-step 4×(400 oC, 5 min) Multi-step Bio-Nano-Space

17 Design of microstructure by the constant orientation gives a unique
possibilities to study microstructure-properties relationship 100 nm Columnar microstructure Equiaxed grains Orientation:constant 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

18 Tem.(oC) Bio-Nano-Space

19 ? Design of orientation by lead source
XRD spectra of PZT 30/70 films: effect of lead-source, 4 x (200oC, 2 min.+ 400oC, 5 min.) Bio-Nano-Space

20 Crystallization mechanism
400oC 1-15 min Bio-Nano-Space

21 Crystallization mechanism
How can be formed? From Pb in Pt! Pb? From PbO in PZT How? Reduction? 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

22 Reflect Array antenna Waveguide with metal iris Unit cell of
radiating element Phase shifting components RETINA: Reliable, tuneable and inexpensive antennas by collective fabrication processes, EU, 6th FP, Thematic priority: Aeronautics and Space EADS (D) TAS (F) IMEC (B) EPFL (CH) COV (F) ESIEE (F) JSI (SI) HYB (SI) Bio-Nano-Space

23 Expected: higher tunability
BST 30/70 Compositions with a higher Ba-content DIELECTRIC CONSTANT At RT: Higher permittivity for solid solutions with a higher Ba/Sr ratio but also a higher T-dependence of e. Expected: higher tunability Temperature dependence of permittivity for BST ceramics Bio-Nano-Space Tagantsev et al., J. Electroceramics, 2003

24 Ba0.3Sr0.7TiO3 (BST) Ba-acetate + Sr-acetate
0.30 Ba (CH3COO) 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) Spinning Pyrolysis Crystallization Bio-Nano-Space

25 Materials characterization:
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 mm) Au/Cr electrode BST film Alumina substrate Substrate: mm x 25.4 mm Bio-Nano-Space Vendik model

26 Microstructure: effect of annealing conditions
700 °C, 15 min. 100 nm 700 °C, 60 min. 900 °C, 15 min. 900 °C, 60 min. Grain size: 70 nm T increases Grain size: 40–45nm Grain size: 80 nm FE-SEM images of BST films on alumina annealed at 700 and 900 °C. Bio-Nano-Space

27 700oC 900oC 100 nm e = 722 ± 50 ne = 1.93 e = 345 ± 35 ne = 1.49 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 mm. Left: surface microstructures of BST films. Bio-Nano-Space

28 Thank to you! 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 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! Bio-Nano-Space


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