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Jo ž ef Stefan Institute Jamova 39 1000 Ljubljana Slovenija marija.kosec@ijs.si

F erroelectrics: Towards Smaller Dimensions and Complex Structure. Marija Kosec. Jo ž ef Stefan Institute Jamova 39 1000 Ljubljana Slovenija marija.kosec@ijs.si. Electronic Ceramics Department , K-5 Head: Prof. Dr. Marija Kosec Staff: 20: 5 PhD, 4 Post-doc, 8 PhD students,

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Jo ž ef Stefan Institute Jamova 39 1000 Ljubljana Slovenija marija.kosec@ijs.si

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  1. Ferroelectrics: Towards Smaller Dimensions • and Complex Structure • Marija Kosec Jožef Stefan Institute Jamova 39 1000 Ljubljana Slovenija marija.kosec@ijs.si

  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)TiO3K(Nb,Ta)O3, • Dielectrics: CuCa3Ti4O12 (CCTO) • Oxide conductors: (La,Sr)CoO3 (LSCO), La-ruthenates, • Multiferoic: BiFeO3 ( BaO, PbO), LaMnO3, • ZnO

  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

  4. Ferroelectric ceramic materials Ferroelectric and dielectric Piezoelectric A: Pb B: Ti,Zr Tunable Polar structur, Electric dipols

  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

  6. lead-free ferroelectric materials: Sodium potassium niobate (K,Na)NbO3s.s. (KNN). KNbO3-NaNbO3phase 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

  7. Bulk: mm, cm range • 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.

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

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

  10. 1 1 2 3 2 3 modeling Marina Santo

  11. LTCC/Au/PZT/ Au LTCC/PZT barriere/ Au/PZT/Au Microstructure after firing 1h850oC.

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

  13. Bulk: mm, cm range 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.

  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 substrate

  15. O CH2 n-1(RO) M O CH2 R Synthesis of PZT solution precursor 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 2-methoxyethanol method CH3-O-C2H4-OH Turova, Turevskaya, Kessler, Yanovskaya, 2002. Budd, Dey, Payne, 1985

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

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

  18. Tem.(oC)

  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.)

  20. Crystallization mechanism 400oC 1-15 min

  21. 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.

  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 SpaceEADS (D)TAS (F)IMEC (B)EPFL (CH)COV (F)ESIEE (F)JSI (SI)HYB (SI)

  23. DIELECTRIC CONSTANT BST 30/70 Compositions with a higher Ba-content • 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 Tagantsev et al., J. Electroceramics, 2003

  24. 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) Spinning Pyrolysis Crystallization

  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: 25.4 mm x 25.4 mm Vendik model

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

  27. 900oC 100 nm 700oC 100 nm e = 722 ± 50 ne = 1.93 e = 345 ± 35ne = 1.49 C-V response of BST filmon alumina annealed at 700°Cand 900 oC for 60 min. 1MHz, RT, gap width: 8.5 ± 1mm. Left: surface microstructures of BST films.

  28. Thanks Dr. BarbaraMalič 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!

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