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Oxidische Materialien: ZrO 2 Jürgen Janek Carsten Korte, Ilia Valov, Robert Klein, Andreas Peters Bjoern Luerßen, Holger Fischer, Eva Mutoro Marcus Rohnke,

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Presentation on theme: "Oxidische Materialien: ZrO 2 Jürgen Janek Carsten Korte, Ilia Valov, Robert Klein, Andreas Peters Bjoern Luerßen, Holger Fischer, Eva Mutoro Marcus Rohnke,"— Presentation transcript:

1 Oxidische Materialien: ZrO 2 Jürgen Janek Carsten Korte, Ilia Valov, Robert Klein, Andreas Peters Bjoern Luerßen, Holger Fischer, Eva Mutoro Marcus Rohnke, Sebastian Meiss Funding: DFG, FCI, BASF AG DFG-Schwerpunktprogramm 1136

2 AG Janek – Oxidische Materialien: ZrO ZrO 2 als elektrokeramisches Material Die Elektrolytmembran (Energietechnologie) HT-Brennstoffzellen (SOFC)..... Grenzflächenchemie..... unkonventionelle Brennstoffe Das Sensormaterial (Sensortechnologie) Elektrochemische Sensoren Ionische Langmuir-Sonden Plasmaanalytik Die Ionenpumpe (Oberflächenchemie/Plasmachemie) Elektrochemische Promotion smart surfaces Ionenpumpen für Plasmen Plasmatechnologie Neue Materalien (und Funktionen…) Substitution/Dotierung Stickstoffionenleiter Lumineszenz Nanoskalige Multischichten

3 AG Janek – Oxidische Materialien: ZrO ZrO 2 (+Y 2 O 3 ) – Die Nernstmasse

4 AG Janek – Oxidische Materialien: ZrO ZrO 2 (+Y 2 O 3 ) – Die Nernstlampe

5 AG Janek – Oxidische Materialien: ZrO Chemistry EngineeringPhysics Solid State Ionics – Open questions? Bulk properties/phenomena: - Equilibrium defect structures - Non-equilibrium defects (low-T) - New electrolytes - Optimisation of functional materials Interfacial phenomena: - surfaces of ionic solids - solid/solid electrodes - kinetics of inner boundaries - interfaces plasma/ionic material Galvanic cells: - new sensors - new fuel cells/batteries - thermovoltaics Methods: - in situ spectroscopy/microscopy - microelectrodes - micro- and nano-ionics

6 AG Janek – Oxidische Materialien: ZrO Electromigration Field-driven reactions Ionic thermoelectricity Thermodiffusion Magnetoresistance nanoscale effects Projects Bulk transport and reaction Interfacial chemistry metal deposition metal dissolution nonlinear effects whisker growth Surface chemistry Plasma electrochemistry Electrochemical promotion of catalysis Electrochemical deposition of ceramic films Solid state kinetics Defect chemistry Solid state electrochemistry

7 AG Janek – Oxidische Materialien: ZrO Electrochemical surface control Electrochemical generation of spillover species - e. g. oxygen on platinum - e.g. sodium on platinum many studies - but no in situ studies on microscopic details Electrochemical Switching of catalysts MeO x on YSZ - thin films of oxides (PLD) - e. g., Fe 2 O 3 Fe 3 O 4 Fe 1-x O Fe no investigations yet (to our knowledge…)

8 AG Janek – Oxidische Materialien: ZrO Electrochemical surface control 24,0 s 22,8 s 22,0 s 21,2 s 20,4 s 19,6 s 18,8 s 18,0 s 0 s 350 µm diffusion coefficient of atomic oxygen: D O [Pt(111), 200°C] = 5.2·10 6 cm 2 /s diffusion coefficient corresponding to work function front: D[Pt(111), 400°C] 5·10 5 cm 2 /s T = 400 °C p(O 2 ) = mbar YSZ surface Pt surface

9 AG Janek – Oxidische Materialien: ZrO interface bulk d Gr Vol electrolyte insulator 2 ( Gr – Vol ) 2 Gr if Gr Vol Vol Gr 1/d 2 ( Gr – Vol ) 1/ Ionic conductivity vs. layer periodicity interface bulk electrolyte Ionic transport in boundary regions

10 AG Janek – Oxidische Materialien: ZrO Vol Gr 1/d 2 ( Gr – Vol ) 1/ Overlap of space charge regions, strong increase in conductivity c( ) d d = δ d > δ d < δ [1]Sata, Eberman, Eberl und Maier, Nature 408, (2000) [2]Sata, Jin-Philipp, Eberl und Maier, Solid State Ionics , (2002) (in the case of CaF 2 /BaF 2 für d > 50 nm) or structural disorder, small change of σ Gr with periodicity c( ) d d = δ d > δ d < δ Ionic transport in boundary regions

11 AG Janek – Oxidische Materialien: ZrO systems: ZrO 2 (+ 12 mol% CaO) / Al 2 O 3 high concentration of mobile oxygen vacancies small Debye length, l D 10 nm 500 nm Al 2 O 3 ZrO nm 2 µm Al 2 O 3 ZrO 2 /Al 2 O 3 SEM images U porous Pt-electrode I j O 2- ½ O e – = O 2– O 2– = ½ O e – substrate Pulsed Laser Deposition: 500 nm Ionic transport in boundary regions

12 AG Janek – Oxidische Materialien: ZrO conductivity increases with 1/d by 2 orders of magnitude Interface: 2δσ Gr 2,4 · S (600 °C) δ < m (TEM results) σ Gr 1,2 · S/cm (600 °C) cf. σ Vol 6,0 · S/cm about 4 orders of magnitude ZrO 2 (+ 12 mol% CaO) / Al 2 O 3 40 nm100 nm200 nm50 nm67 nm33 nm conductivity reciprocal thickness Ionic transport in boundary regions

13 AG Janek – Oxidische Materialien: ZrO Ion emission from YSZ Y. Torimoto et al., Jpn. J. Appl. Phys. 36 (1997) L238 Y. Fujiwara at al., J. Electrochem. Soc. 150 (2003) E117

14 AG Janek – Oxidische Materialien: ZrO Ion pumping into plasmas

15 AG Janek – Oxidische Materialien: ZrO Optisches System: - Nd:YAG gepumter Farbstofflaser (10 Hz / 355 nm) - Farbstoff : 1:1 Mischung Coumarin 47/ Filter : ( ) nm Parallelplattenentladung: - kapazitiv, asymmetrisch - f = 13,56 MHz max. U eff ~ 600 V Arbeitsgas : Sauerstoff - p = Pa - Gasfluß = sccm Electrodes: - radius r = 40 mm, - distance d = mm Resolution: axial: - max. shift 100 mm, - min. step size 0,3 mm, - min. distance beam-electrodes 0,5 mm radial: - max. shift 76 mm, - min. sep size 1 mm Institut für Physik Universität Greifswald Ion pumping into plasmas TALIF-Experiment

16 AG Janek – Oxidische Materialien: ZrO Ion pumping into plasmas oxygen atom density M. Rohnke, S. Peters, J. Janek and J. Meichsner submitted to J. Appl. Phys. (2004) YSZ electrode steel electrode

17 AG Janek – Oxidische Materialien: ZrO (Zr,Y)(N,O) 2 – A nitrogen electrolyte 1 cm as-deposited annealed at 700 °C for 15 min 15 min at 700 °C applied voltage U = -2.2V as-deposited films show dark violet color SIMS analysis proofs that nitrogen remains in YSZ after annealing (i.e. the violet color is related to reduction of YSZ)

18 AG Janek – Oxidische Materialien: ZrO (Zr,Y)(N,O) 2 – A nitrogen electrolyte as-deposited (500 °C deposition temperature) 18 O / ( 16 O + 18 O) YSZ/Al 2 O 3 Multilayers100nm/layer Multilayers100nm/layer YSZ

19 AG Janek – Oxidische Materialien: ZrO (Zr,Y)(N,O) 2 – A nitrogen electrolyte thermally annealed 700 °C, 15 min 18 O / ( 16 O + 18 O)

20 AG Janek – Oxidische Materialien: ZrO (Zr,Y)(N,O) 2 – A nitrogen electrolyte field experiment 700 °C for 15 min U = -2.2 V 18 O / ( 16 O + 18 O) oxygen is much faster than nitrogen The applied electric field influences the nitrogen profile…

21 AG Janek – Oxidische Materialien: ZrO Dr. Marcus RohnkeDr. Bjoern LuerssenBernhard Franz Boris MogwitzDr. Carsten Korte Ilia ValovRobert Klein Klaus PepplerEva Mutoro Dr. Doh-Kwon LeeHolger FischerAndreas PetersSebastian MeißClaus C. Fischer Prof. Jürgen Janek

22 AG Janek – Oxidische Materialien: ZrO


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