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Vanadium Oxide Extended Frameworks: *Structural Chemistry & Applications

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2009 OMEE. Lviv, Ukraine

2009 OMEE. Lviv, Ukraine

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    Vanadium  Oxide  Extended  Frameworks: *Structural Chemistry & Applications Vanadium Oxide Extended Frameworks: *Structural Chemistry & Applications Presentation Transcript

    • Oxide Materials for Electronic Engineering Peter Y. Zavalij X-ray Crystallography Center Department of Chemistry and Biochemistry University of Maryland at College Park, Maryland, USA Vanadium Oxide Extended Frameworks: Structural Chemistry & Applications
    • University of Maryland at College Park Located North-East of Washington, DC: only 15 miles from the White House z
    • University of Maryland at College Park http://www.umd.edu/ The University has : 26,000 undergraduate 11,000 graduate students 13,000 employees of which 3,000 faculties
    • http://www.chem.umd.edu/ The Department is located in 6 buildings/wings and has about 50 professors, 100+ graduate students Chemistry & Biochemistry Bioscience Research building The Department of Chemistry and Biochemistry in the College of Chemical and Life Sciences at the University of Maryland is gaining momentum. Apply Here
    • X-ray Crystallographic Center http://www.chem.umd.edu/facility/xray/ Single Crystal Diffraction Chemical Crystallography X-ray Powder Diffraction Materials Characterization
    • Why Vanadium Oxides?
      • Vanadium oxides and their intercalates present:
        • Very rich chemistry because of wide range of oxidation states +5, +4, +3, …
        • Interesting crystal-chemistry – amazing frameworks due to variety of coordination polyherda: tetrahedra, pyramids, octahedra, etc.
      • And therefore exhibit important properties such as:
        • Red-Ox – used in Electrochemical application;
        • Magnetic – which are often unique;
        • Catalytic – used in oxidative catalysis.
      • Outlines:
      • Application in Battery Materials
      • Chemistry & Structures
      • Extended Frameworks
      • Modulation and Disorder
      • Nano-materials
        • Rechargeable Battery Materials
          • Red-Ox Reaction - wide range of oxidation states V: 5+…3+, Fe: 3+…2+, Mn: 4+…2+ vs. Co: 3½ +…3+
          • Open Frameworks - minimal structural changes during cycling
          • Electrochemical Properties - Performance: capacity, stability, safety
      Electrochemical Cell Anode: pure Li, Li+C graphite , Li-Sn alloys Cathode: Metal Oxide, Phosphate + Binder (teflon) + Conductor (carbon black ) Electrolyte - organic solvent + Li salt: LiClO 4 , LiPF 6 , LiAsF 6 , … + LiB(C 2 O 4 ) 2
    • Electrochemical Cycling
    • Multiple Steps & Slopes: Solid Solution: Li x M n O m ( x  0) Two Phase System: x LiM n O m + (1- x )M n O m (0  x  1) Electrochemical Behavior Sn Li 0.4 Sn LiSn Li 2.3 Sn Li 2.6 Sn Li 3.6 Sn 0 1 2 3 4 5 0 0.2 0.4 0.6 0.8 1.0 x Potential, Volts 0 1 2 3 4 0 1 2 3 Potential, Volts x Capacity, mAh/g 0 50 100 150 200 2.1 2.5 2.9 3.3 3.7 Potential, Volts NH 4 V 4 O 10 Li 0.5 NH 4 V 4 O 10 Li 1.0 NH 4 V 4 O 10 Li 1.5 NH 4 V 4 O 10 Li 3 NH 4 V 4 O 10
    • Structural Relationship of Vanadyl Phosphates in Electrochemical Cycling unknown structure Parental  -VOPO 4 Disordered I4 1 /amd P1 - Pnma P2 1 /n  -VOPO 4 C2/c Li 1.6 …
    • Coordination Polyhedra vs. pH in tma Intercalates tma = [N(CH 3 ) 4 ] + ~tma(V 2 O 5 ) 6 tma(V 2 O 5 ) 4 Li x V 2 O 4 . H 2 O tmaV 3 O 7 Li 3 VO 4 2 4 6 8 10 pH tma(V 2 O 5 ) 2
    • Coordination Polyhedra & Oxidation State 5+ 3+… 5+ ... 4+ TB Trigonal Bipyramid T Tetrahedra SP Square Pyramid O d Distorted Octahedra O r Regular Octahedra Oxidation State
    • Metamorphosis of V-O Frameworks pH T+T TB, SP SP O d Single Chain Double Chain Single Layer Double Layer (  ) 3D Framework Basic Acidic VO 3 VO 2 Composition O:V
    • Square-Pyramids (SP) chains “ {UU}” {UD} {UUDD} “ {ud}” {uudd} “ {UuDd}”  {Z} c d e f b a
    • Octahedral (O) chains {OO  OO}  {X} {OO|OO}  {Q} {OO} {o} {oo} {o/}  {W}
    • V-O Frameworks: SP class
    • SP+T class
    • O class
    • O+SP class
    • O+T class
    • Stoichiometry & Dimensionality
    • Oxidation State and Composition - Cluster - Extended framework pH
    • (NH 4 ) 2 V 3 O 8 (RT) 295 K Sp. gr. P4bm a = 8.8997(5) Å c = 5.5732(4) Å V = 441.42(5) Å 3
      • NH 4 disordered in two orientations (blue & yellow)
      • Additional diffraction peaks at low temperature
      NH 4 + a b
    • (NH 4 ) 2 V 3 O 8 ( LT ) – 3+2 modulation Incommensurate Modulation Vectors Green – main unit cell (strong reflections) Red – modulation vectors 3+2 Superspace Group: P4bm ( - αα½, αα½)0 gg Lattice Centering: (0, 0, ½, ½, ½) a = 8.8792(4) Å c = 11.1108(6) Å = 2× c main V = 875.98(8) Å 3 α = 0.3095(1)
    • (NH 4 ) 2 V 3 O 8 – ADPs at RT & LT LT RT
      • The same small ADPs for both V atoms
      • Displacement of terminal O (V=O) is smaller at LT
      • Stronger anisotropy of bridging O atoms
      • O 3 displacement (red ellipse) is greater at LT
      • O 4 displacement in V 2 O 7 (red arrows) is greater at LT
      • ADPs depict in-plane rotation of VO 5 and VO 4
      Average structure a b
    • (NH 4 ) 2 V 3 O 8 - Rotation of Polyhedra
      • Coordination polyhedra VO 5 & VO 4 cannot be rigid units
      a b
    • (NH 4 ) 2 V 3 O 8 - Rotation of Groups
      • Circular motions of rigid units VO 5 & V 2 O 7
      • Does not explain large ADP of bridging O in V 2 O 7
      • Symmetry changes
      ? a b
    • (NH 4 ) 2 V 3 O 8 - Rotation & Translation
      • Circular motions of VO 5
      • BOTH circular motions of VO 4 & translational motions of V 2 O 7
      • Explains large ADP of bridging O in V 2 O 7
      a b
    • tma V 4 O 10 at RT and LT
      • Displacement in V 4 O 10 layer practically identical at RT and LT
      • tma is less ordered at RT (previous slide)
      • Terminal (V=O) oxygen atoms are more modulated in bc plane, while rest V and O atoms are displaced perpendicularly to the layer
      RT LT Average structures c b c a
    • tma V 4 O 10 - RT 293 K Sp. gr. Cmcm a = 17.1059(4) Å b = 6.6369(1) Å c = 11.7287(2) Å V = 1331.56(4) Å 3 R F = 4.24%
      • Disordered tma (in m2m position)
      • Initially refined in Cmc2 1 – missed satellites (green)
      • 1D Incommensurate modulation: q = 0.404b *  2 / 5 b *
      • 3+1 Superspace Group: Cmc2 1 (0 β 0)s00, β = 1-q = 0.5956(1)
      Average structure Diffraction pattern c b c a q a * b *
    • tma V 4 O 10 - LT 100 K Sp. gr. Cmc2 1 a = 16.7313(10) Å b = 6.5977(4) Å c = 11.7586(7) Å V = 1298.01(13) Å 3 R F = 8.88%
      • The same disorder as at RT - when refined in main cell
      • Can be refined as regular structure in super-cell:
        • a S =a, b S =5b, c S =2c; V S =10V
      • 2D Commensurate modulation: q 1 = 1 / 5 b * q 2 = 1 / 2 c *
      Average structure Diffraction pattern q 2 b * c * q 3 c a
    • tma V 4 O 10 ( LT ) super cell different type of layer
      • Green – Tetrahedra
      • Red – Square Pyramids
      Super Cell Average structure
      • Disordered tma and tea
      • Misfit:
        • Cell dimension – b  3.6 Å
        • tma & tea size – at least 6 Å
      • Powder data:
      • tma V 8 O 20
      • Sp. gr. C2/m
      • a = 23.655(2) Å
      • b = 3.5931(3) Å
      • c = 6.3175(5) Å
      • = 103.060(4)°
      • V = 523.05(8) Å 3
      Single crystal : (weak diffraction) tea V 8 O 20 Sp. gr. C2/m a = 25 .52(2) Å b = 3.569(2) Å c = 6.276(4) Å  = 98.91(1) ° V = 564.9(6) Å 3 tma - [(CH 3 ) 4 N] + tea - [(CH 3 CH 2 ) 4 N] + Composite Structures: tma V 8 O 20 & tea V 8 O 20 10  m
    • Vanadium Oxide Nano-rolls – R n V 7 O 16 R – dodecyl amine Layers from BaV 7 O 16 Nano-rolls (SEM) Nano-rolls Model Atomic Pair Distribution Function Phys. Rev. B , 2004
    • Property Magnetism Structure Catalysis Instead of Conclusion Battery
    • Thank You! Oxide Materials for Electronic Engineering
    • Abnormalities in Reciprocal Space Crystal/Structure What can be seen in Reciprocal Space Disordered classic None (single lattice) OD single lattice + diffuse peaks Twinned merohedral single lattice (several lattices perfectly coinciding with each other) non-merohedral, split or co-crystal several lattices with common origin (related by rotation or reflection) Modulated incommensurate main lattice usually with stronger peaks and additional lattice(s) shifted from the origin commensurate strange reflections conditions, main lattice may have stronger peaks Composite incommensurate several main lattices and additional lattices shifted from origin commensurate strange reflections conditions; main lattices may have stronger peaks Quasicrystal absent 3D lattice, non-crystallographic symmetry, e.g. 5-fold axis