1 / 40

RUTILE CRYSTAL STRUCTURE

z. y. x. RUTILE CRYSTAL STRUCTURE. SEEING THE 1-D CHANELS IN RUTILE. NEW METASTABLE POLYMORPH OF TiO 2 BASED ON K 2 Ti 4 O 9 SLAB STRUCTURE - (010) PROJECTION SHOWN. K + at y = 3/4. K + at y = 1/4. Different to rutile, anatase or brookite forms of TiO 2.

lacey
Télécharger la présentation

RUTILE CRYSTAL STRUCTURE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. z y x RUTILE CRYSTAL STRUCTURE

  2. SEEING THE 1-D CHANELS IN RUTILE

  3. NEW METASTABLE POLYMORPH OF TiO2 BASED ON K2Ti4O9 SLAB STRUCTURE - (010) PROJECTION SHOWN K+ at y = 3/4 K+ at y = 1/4 Different to rutile, anatase or brookite forms of TiO2

  4. Finding the number of crystallographically inequivalent oxygen sites in the K2Ti4O9 slab and the number of each [Ti(IV)4O9]2- Oxygen count 1/3 + 3/4 1/3 1/4 1/4 1/4 1/3 1/2 1/2 1/2 1/2 Oxygen count 4 + 1/2 +2 +1/3 1 1 1 1 1/3 1/4 1/4 1/4 Oxygen count 1/3 + 3/4 Topotactic loss of H2O from H2Ti4O9 to give “Ti4O8” (TiO2 slabs) plus H2O, where two bridging oxygens in slab are protonated (TiOHTiOTiOH)

  5. CHIMIE DOUCE: SOFT CHEMISTRY • Figlarz synthesis of new WO3 • WO3(cubic form) + 2NaOH  Na2WO4 + H2O • Na2WO4 + HCl (aq)  gel • Gel (hydrothermal) 3WO3.H2O • 3WO3.H2O (air, 420oC) WO3 (hexagonal tunnel structural form of tungsten trioxide) • More open tunnel form than cubic ReO3 form of WO3

  6. Slightly tilted cubic polymorph of WO3 with corner sharing Oh WO6 building blocks, only protons and smaller alkali cations can be injected into cubic shaped voids in structure to form bronzes like NaxWO3 and HxWO3 1-D hexagonal tunnel polymorph of WO3 with corner sharing Oh WO6 building blocks, can inject larger alkali and alkaline earth cations into structure to form bronzes like RbxWO3 and BaxWO3

  7. Apex sharing WO6 Oh building blocks Hexagonal tunnels Injection of larger M+ cations like K+ and Ba2+ than maximum of Li+ and H+ in c-WO3 Structure of h-WO3 showing large 1-D tunnels

  8. MOLTEN SALT ELECTROCHEMICAL REDUCTIONS OF OXYANIONS: GROWTH OF CRYSTALS • Molten mixtures of precursors - product crystallizes from melt - inert crucibles and electrodes like Pt, graphite CATHODE • Reduction of TM oxides to lower oxidation state materials • CaTi(IV)O3 (perovskite)/CaCl2 (850oC)  CaTi(III)2O4 (spinel) • Na2Mo(VI)O4/Mo(VI)O3 (675oC) Mo(IV)O2 (large crystals) • Li2B4O7/LiF/Ta(V)2O5 (950oC) Ta(II)B2 • Na2B4O7/NaF/V(V)2O5/Fe(III)2O3 (850oC) Fe(II)V(III)2O4 (spinel)

  9. SYNTHETIC FORM: SHAPE IS EVERYTHING IN THE MATERIALS WORLD • When thinking about a solid state synthesis of a particular composition it is also important to plan the form of the material that will ultimately be required for a specific application • Shape is everything when it comes to designing structure-property-function-utility relations • Form counts - polycrystalline, nanocrystalline, film, superlattice, wire, single crystal and so forth

  10. Li+ Li+ Li+ Li+ Li+ Li Li3N LixC LixCF LiAl LiSn LixMnO2 PEO Li+ BASICS LSSB: INJECTION-INTERCALATION CATHODES TiO2, NbSe3, WO3, MoS2, V6O13, LixCoO2 • Li+/e- charge equivalents of anode • Voc, DEF(anode-cathode) • Electrode-electrolyte interfacial kinetics • Polymer segment dynamics • Polymer Tg controls crystalline vs glassy • Li+/PEO cooperative motion effects • Goal Li+ RT conductivity • Needs liquid (low MW PEO) plastisizers • Electrode-electrolyte mechanical stability • Electrode-electrolyte chemical stability • Rocking chair architecture • Secondary battery can be cycled • Operational lifetime • Safety, environmentally correct anode electrolyte cathode SPE

  11. LiCoO2 LixC6 ROCKING CHAIR LSSB Li LiCoO2

  12. HOW TO SYNTHESIZE A BETTER LSSB?Improved Performance Cathode, Anode and Electrolyte

  13. TEMPLATE SYNTHESIS OF NANOSCALE BATTERY CATHODE MATERIALS

  14. A BETTER BATTERY CATHODE USING NANOSCALE MATERIALS - NANODIFFUSION LENGTHS FOR Li+ DIFFUSIVE INTERCALATION • Template synthesis is a versatile nanomaterial fabrication method used to make monodisperse nanoparticles of a variety of materials including metals, semiconductors, carbons, and polymers. • The template method has been used to prepare nanostructured lithium-ion battery electrodes in which nanofibers or nanotubes of the electrode material protrude from an underlying current-collector surface like the bristles of a brush. • Nano-structured electrodes of this type composed of carbon, LiMn2O4, V2O5, Sn, TiO2 and TiS2 have been prepared.

  15. A BETTER BATTERY CATHODE USING NANOSCALE MATERIALS - NANODIFFUSION LENGTHS FOR Li+ DIFFUSIVE INTERCALATION • In all cases, the nanostructured electrode showed dramatically improved rate capabilities relative to thin-film control electrodes composed of the same material. • The rate capabilities are improved because the distance that Li must diffuse in the solid state (the current- and power-limiting step in Li-ion battery electrodes) is significantly smaller in the nanostructured electrode. • For example, in a nanofiber-based electrode, the distance that Li must diffuse is restricted to the radius of the fiber, which may be as small as 50 nm.

  16. A BETTER BATTERY CATHODE USING NANOSCALE MATERIALS - NANODIFFUSION LENGTHS FOR Li+ DIFFUSIVE INTERCALATION • Beating mechanical stability problem of repeated intercalation-deintercalation expansion-contraction cycles • In addition to improved rate capabilities, the nanostructured electrodes do not suffer from poor cyclability observed for conventional electrodes. • This is because the absolute volume changes in the nanofibers are small, and because of the brush-like configuration, there is room to accommodate the volume expansion around each nanofiber. • Improved cycle life results show nanostructured electrode can be driven through 1400 charge/discharge cycles without loss of capacity.

  17. nc-TiO2 Ti(IV)-X- surface coordinated anion Li+ cation Ti(IV)-O surface coordinated oxygen of PEO polymer chain PEO polymer chain coordinated to Li+ cation and surface Ti(IV) Nanocrystal-PEO electrolytes solid plasticisers for LSSB

  18. nc-TiO2 LiClO4-PEO-nc-TiO2 • LiClO4-PEO-nc-TiO2 -high surface areananocrystalline ceramic • Brnsted and Lewis acid-base sites - surface Ti(IV) coordination to O(CH2CH2)- • Surface Ti(IV) binding to counteranion X- • Polymer-particle crosslinking - no 60oC glass transition • nc-TiO2 stabilizes glassy polymer state at RT • Domains of local polymer disorder at PEO-nc-TiO2 interface • Optimal anchoring promotes local structural and dynamical modifications • High RT Li+ conductivity • Excellent mechanical stability, improved stress-strain curves • Reduced reactivity with solid compared to liquid plasticizer • Less cooperative PEO segmental motion with enhanced interfacial mobility of Li+ • Transport numbert(Li+),0.3 pristine LiClO4-PEO, 0.6 in LiClO4-PEO-nc-TiO2

  19. nc-CERAMIC OXIDES: SOLID PLASTICISERS IN POLYMER-ELECTROLYTE LITHIUM BATERIES • LiClO4 : PEO = 1 : 8, 10 wt% nc-TiO2 or Al2O3, • anchoring PEO oxygens and counteranions to Brnsted/Lewis acid surface sites, • enhanced corrosion resistance of electrodes, • better mechanical stability PEO, • higher Li+ conductivity & transport number, • local disorder of polymer, loss of Tg, stabilizes RT glassy state, • discards need for PEO-Li+ cooperative segmental motion

  20. METHODS FOR SYNTHESIZING NANOCLUSTERS AND NANOCRYSTALS • Vaporization of metals (thermal, laser ablation) in inert gas - condensation of mixture - Pt, Au • Supersonic molecular beams - Knudsen cell vaporization with inert gas expansion - condensation into vacuum and mass selection and mass spectroscopy detection - Si, GaAs • Plasma-arc vaporization - condensation - WC, SiC • Aerosol spray pyrolysis of salt, sol-gel precursor solution - Y3Fe5O12, Mn0.8Zn0.2FeO4, PbZr0.52Ti0.48O3, YBa2Cu3O7, ZrO2, TiO2 • Microemulsions, micelles, zeolites - precursors - confined nucleation and arrested nanocluster growth - capped CdSe, FePt, TiO2, YBa2Cu3O7

  21. Peter Day, Chemistry in Britain LENGTH SCALES IN CHEMISTRY, PHYSICS AND BIOLOGY

  22. Spatial and quantum confinement and dimensionality

  23. WHEN IS SMALL GOOD?

  24. WHEN IS SMALL GOOD? Sub-dividing or perforating matter mono- or polydispersed particles, crystalline or amorphous, micro (<10 Å), meso (10-1000 Å) or macro (>1000 Å) length scale, organized or random arrangements, channels or pores, structure-composition-defects, surface area, sites, charge, hydrophobicity, functionality Property-function QSEs,  of e, h, or hrelative to materials size, dimensionality, interaction strength of components, interconnection and integration of parts, hierarchy and system architecture, function Properties that are size and shape tunable mechanical, thermal, acoustical, dielectric, surface vs bulk, electrical, optical, electro-optical, magnetic, photonic, catalytic, photochemical, photophysical, electrochemical, separation, recognition, composite

  25. EgC = EgB + (h2/8R2)(1/me* + 1/mh*) - 1.8e2/R Quantum localization term Coulomb interaction between e-h CAPPED MONODISPERSED SEMICONDUCTOR NANOCLUSTERS nMe2Cd + nnBu3PSe + mnOct3PO  (nOct3PO)m(CdSe)n + n/2C2H6 + nnBu3P

  26. ARRESTED GROWTH OF MONODISPERSED NANOCLUSTERSCRYSTALS, FILMS ANDLITHOGRAPHIC PATTERNS nMe2Cd + nnBu3PSe + mnOct3PO  (nOct3PO)m(CdSe)n + n/2C2H6 + nnBu3P

  27. MONODISPERSED CAPPED CLUSTER SINGLE CRYSTALS Rogach AFM 2002 methanol 2-propanol toluene

  28. THINK SMALL DO BIG THINGS!!! EgC = EgB + (h2/8R2)(1/me* + 1/mh*) - 1.8e2/R

  29. SELF-ASSEMBLING AUROTHIOL CLUSTERS HAuCl4(aq) + Oct4NBr (Et2O)  Oct4NAuCl4 (Et2O) nOct4NAuCl4(Et2O) + mRSH + 3nNaBH4 Aun(SR)m

  30. CAPPED METAL CLUSTER CRYSTAL CLUSTER SELF-ASSEMBLY DRIVEN BY HYDROPHOBIC INTERACTIONS BETWEEN ALKANE TAILS OF ALKANETHIOLATE CAPPING GROUPS ON GOLD NANOCRYSTALLITES

  31. CAPPED FePt NANOCLUSTER SUPERLATTICE HIGH-DENSITY DATA STORAGE MATERIALS

  32. ZEOLATE CAPPED SEMICONDUCTOR CLUSTERS

  33. ZEOLATE LIGAND Crown ether - zeolate ligand analogy - metal coordination chemistry of zeolites

  34. TOPOTACTIC MOCVD Intrazeolite reaction of acid zeolite Y (HY) with known amounts of Me2Cd or Me4Sn vapors Gives anchored MeCdY and Me3SnY, which react with H2S or H2Se to create encapsulated and zeolate capped nanoclusters Cd4S4Y and Sn4S6Y Defined by Reitveld PXRD structure refinement

  35. MOCVD TOPOTAXY OF INTRAZEOLITE TIN SULFIDE, CADMIUM SELENIDE AND SILICON AND GERMANIUM NANOCLUSTERS

  36. INTRAZEOLITE CVD OF SILICON NANOCLUSTERS

  37. QUANTUM CONFINED SILICON - < 5 nm -MAKING SILICON GLOW THROUGH NANOCHEMISTRY • Si2H6 + H56Y  (Si2H5)8-Y • (Si2H5)8-Y  (Si8)8-Y • Superlattice of Si8 clusters in ZY

  38. INTRAZEOLITE TUNGTEN OXIDE NANOCLUSTERS

  39. NANOWIRES - FABRICATION OR SYNTHESIS • Top down advanced nanolithography fabrication methods - expensive and time consuming • Bottom up chemical synthesis methods - economical and fast • Creation of 1D nanowires - used as functional components and interconnects in building nanodevices and nanocircuitry through self assembly strategies • Most successful purely synthesis methods involve vapor-solid VS, vapor-liquid-solid VLS, solution-liquid solid SLS and solution-solid SS processes • These chemical approaches have led to carbon nanotubes, metal and semiconductor nanowires and a range of inorganic materials • Other approaches involve structure directing templates like channels in porous alumina, hexagonal lyotropic liquid crystals and block copolymers

More Related