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Mixed-valence vanadates at high-pressures Andrzej Grzechnik Institute of Crystallography, RWTH Aachen University. Vanadium coordination polyhedra in vanadates in relation to the oxidation states of vanadium at atmospheric pressure.

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slide1

Mixed-valence vanadates at high-pressures

AndrzejGrzechnik

Institute of Crystallography, RWTH Aachen University

slide2

Vanadium coordination polyhedra in vanadates in relation to the oxidation states

of vanadium at atmospheric pressure

P.Y. Zavalij and M.S. Whittingham, Acta Cryst. B55, 627 (1999)

slide3

Vanadium coordination polyhedra in vanadates in relation to the oxidation states

of vanadium at atmospheric pressure

  • ► Electrochemistry
  • ► Catalysis
  • ► Correlated electron systems
  • Spin-Peierls transitions
  • Spin gap formation
  • Charge, spin & orbitalordering Metal-insulatortransitions
  • ► Magnetism

P.Y. Zavalij and M.S. Whittingham, Acta Cryst. B55, 627 (1999)

slide4

Rutile type

Binary vanadium oxides

Wadsley phases: VnO2n+1 (n = 3, 4, 6)

the VO2 – V2O5 system

V2O5 (Pmmn)

VO2 (P42/mnm)

slide5

Rutile type

Binary vanadium oxides

Wadsley phases: VnO2n+1 (n = 3, 4, 6)

the VO2 – V2O5 system

V2O5 (Pmmn)

VO2 (P42/mnm)

n = 3

V3O7 (C2/c)

An insulator and a uniaxial ferromagnet: H. Nishihara, Y. Ueda, K. Kosuge, H. Yasuoka, S. Kachi, J. Phys. Soc. Jpn. 47, 790 (1979).

slide6

Rutile type

Binary vanadium oxides

Wadsley phases: VnO2n+1 (n = 3, 4, 6)

the VO2 – V2O5 system

V2O5 (Pmmn)

VO2 (P42/mnm)

n = 4

V4O9 (Pnma)

An antiferromagnet: S. Yamazaki, C. Li, K. Ohoyama, M. Nishi, M. Ichihara, H. Ueda, Y. Ueda, J. Solid State Chem. 183, 1496 (2010).

slide7

Rutile type

Binary vanadium oxides

Wadsley phases: VnO2n+1 (n = 3, 4, 6)

the VO2 – V2O5 system

V2O5 (Pmmn)

VO2 (P42/mnm)

n = 6

V6O13 (Pnma)

A metal-insulator phase transition followed by an antiferromagnetic transition: Y. Ueda, K. Kosuge, S. Kachi, Mater. Res. Bull. 11, 293 (1976).

slide8

Corundum type

Rutile type

Binary vanadium oxides

Magnéli phases: VnO2n-1 (n = 3÷9)

the V2O3 – VO2 system

VO2 (P42/mnm)

V2O3 (R-3c)

V3O5 (Cc)

V8O15 (P-1)

slide9

Vanadium coordination polyhedra in vanadates in relation to the oxidation states

of vanadium at high pressures?

slide10

Vanadium coordination polyhedra in vanadates in relation to the oxidation states

of vanadium at high pressures

P

An interplay of theeffects of a chemicalcomposition and of highpressureonthestructuralstability

and physicalproperties of mixedvalencevanadates

slide11

Ca3V2O8 at high pressures

palmierite type

R3c

slide12

Ca3V2O8 at high pressures

Onset of amorphization at about 10 GPa

A. Grzechnik, Chem. Mater. 10, 1034 (1998)

A. Grzechnik, J. Solid State Chem. 139, 161 (1998)

palmierite type

R3c

slide13

Ca3V2O8 at high pressures

HP-HT synthesis of a powder material

11 GPa, 1373 K

C2/m

palmierite type

R3c

A. Grzechnik, Solid State Sciences 4, 523 (2002)

slide15

V2O5 and AxV2O5 (A = Li, Na, Cs, Ag, Mg, Ca, …; x ≤ 1)

NaV2O5 (Pmmn)

b-Na0.33V2O5 (C2/m)

Wadsley-type bronze

slide16

Pressure-induced superconductivity in b-Na0.33V2O5: TSC = 8 K, P = 8 GPa

Phase transition from the charge ordered to the superconducting phase at 8 K and 8 GPa?

T. Yamauchi, Y. Ueda, N. Môri, Phys. Rev. Lett. 89, 057002 (2002)

slide17

Local structures in high-pressure phases of V2O5

A. Grzechnik, Chem. Mater. 10, 2507 (1998)

I. Loa, A. Grzechnik, U. Schwarz, K. Syassen, M. Hanfland, R.K. Kremer, J. Alloys Comp. 317–318, 103 (2001)

slide18

High-pressure phases of V2O5 and NaV2O5 from powder diffraction?

A. Grzechnik, Chem. Mater. 10, 2507 (1998)

I. Loa, A. Grzechnik, U. Schwarz, K. Syassen, M. Hanfland, R.K. Kremer, J. Alloys Comp. 317–318, 103 (2001)

slide19

High-pressure phases of b-Na0.33V2O5 from powder diffraction?

High-pressure synchrotron powder diffraction at room temperature

K. Rabia, A. Pashkin, S. Frank, G. Obermeier, S. Horn, M. Hanfland, C.A. Kuntscher, High Press. Res. 29, 504 (2009)

slide20

(NH4)2V3O8fresnoite

Synchrotron single-crystaldiffraction (D3/Hasylab)

A. Grzechnik, T.Z. Ren, J.M. Posse, K. Friese, Dalton Trans. 40, 4572 (2011)

Ambient pressure 6.90 GPa

V4+

V5+

P4bm

slide21

(NH4)2V3O8fresnoite

Synchrotron single-crystaldiffraction (D3/Hasylab)

A. Grzechnik, T.Z. Ren, J.M. Posse, K. Friese, Dalton Trans. 40, 4572 (2011)

Ambient

Ambient pressure 6.90 GPa

V4+

V5+

No charge transfer

P4bm

P4/mbm

slide22

MV6O11 compounds

(M = Na, K, Sr, Ba, Pb)

P63/mmc

M+V33+V34+O11 or M2+V43+V24+O11

NaV6O11: A. Grzechnik, Y. Kanke, K. Friese, J. Phys.: Condens. Matter 20, 285208 (2008)

BaV6O11: K. Friese, Y. Kanke, A. Grzechnik, Acta Cryst. B65, 326 (2009)

V(1)O6

M

V(2)O6

V(1)O6

V(3)O5

regular Kagomé lattice

Structures related to magnetoplumbite Pb(Fe3+,Mn3+)12O19

slide23

Phasetransitions in NaV6O11: low T

64.2 K 80 K TH = 243 K



║

Na+

Spontaneous

magnetization

with the easy

axis II to [001]

V4+(2)O6

V3+(1)O6

V4+(3)O5

► A Curie-Weiss paramagnetic metal at ambient conditions

►Spontaneous magnetization is suppressed at high pressures (Tc ↓ P↑)

while the TH temperature increases on compression (*) and is expected

to be at 1.15 GPa and room T

(*) T. Naka, T. Matsumoto, Y. Kanke, K. Murata, Physica B206/207, 853 (1995)

slide24

Phasetransitions in BaV6O11: low T

Single-crystal growth at 6 GPa and 1473-2323 K

Yasushi Kanke (NIMS, Tsukuba)

Ba2+

V(2)O6

V(1)O6

V(3)O5

slide25

Phasetransitions in BaV6O11: low T

Single-crystal growth at 6 GPa and 1473-2323 K

Yasushi Kanke (NIMS, Tsukuba)

P63mc ↔ P63/mmc

250 K

Ba2+

115 K

75 K

V(2)O6

V(1)O6

V(3)O5

Specific heat

slide26

Phasetransitions in BaV6O11: low T

Single-crystal growth at 6 GPa and 1473-2323 K

Yasushi Kanke (NIMS, Tsukuba)

P63mc ↔ P63/mmc

250 K

Ba2+

115 K

75 K

V(2)O6

No structural phase transitions

(no Cmc21 phase)

V(1)O6

V(3)O5

Specific heat

slide27

Phasetransitions in BaV6O11: low T

Single-crystal growth at 6 GPa and 1473-2323 K

Yasushi Kanke (NIMS, Tsukuba)

P63mc ↔ P63/mmc

250 K

115 K

115 K

75 K

75 K

No structural phase transitions

(no Cmc21 phase)

Specific heat

Magnetic susceptibility

slide28

Phasetransitions in NaV6O11and BaV6O11: breakingtheKagomélattice

slide29

Phasetransitions in NaV6O11and BaV6O11: breakingtheKagomélattice

NaV6O11

slide30

Phasetransitions in NaV6O11and BaV6O11: breakingtheKagomélattice

V(1)

V(2)

290 K

2.86 Å

NaV6O11

slide31

Phasetransitions in NaV6O11and BaV6O11: breakingtheKagomélattice

V(1)

V(2)

290 K

2.86 Å

85.5 K

NaV6O11

2.72 Å

2.99 Å

slide32

Phasetransitions in NaV6O11and BaV6O11: breakingtheKagomélattice

V(1)

V(2)

290 K

2.86 Å

85.5 K

4.2 GPa

NaV6O11

2.72 Å

2.99 Å

3.01 Å

2.66 Å

slide33

Phasetransitions in NaV6O11and BaV6O11: breakingtheKagomélattice

NaV6O11 BaV6O11

slide34

Phasetransitions in NaV6O11and BaV6O11: breakingtheKagomélattice

NaV6O11

Hardly any bond valence changes at V sites

BaV6O11

Bond valence changes at all V sites

Charge transfer

M

V(2)O6

V(1)O6

V(3)O5

slide35

Mixed-valencevanadates MV4O8 (M = Y, Yb, Lu)

3V3+ + 1V4+

K. Friese, Y. Kanke, A.N. Fitch, A. Grzechnik, Chem. Mater. 19, 4882 (2007)

K. Friese, Y. Kanke, A.N. Fitch, W. Morgenroth, A. Grzechnik, Acta Cryst. B64, 652 (2008)

slide36

→b

Fe(1)O6

Fe(2)O6

Ca

↓a

→b

Pnam (Z = 4)

a = 9.230 Å

b = 10.705 Å

c = 3.024 Å

↓c

Orthorhombic

Pnam

a= 9.230 Å

b=10.705 Å

c= 3.024 Å

Calcium ferrite type structure (CaFe2O4)

slide37

→b

V(1)O6

V(3)O6

V(2)O6

V(4)O6

Yb

↓a

→b

P 1 21/n 1 (Z = 4)

a = 9.0648(3) Å

b = 10.6215(4) Å

c = 5.7607(1) Å

 = 90.184(3)°

↓c

a-YbV4O8

slide38

→b

V(1)O6

V(3)O6

V(2)O6

V(4)O6

Yb

↓a

→b

A 21/d 1 1 (Z = 8)

a = 9.030(5) Å

b = 21.44(3) Å

c = 5.752(2) Å

 = 89.911(3)°

↓c

β-YbV4O8

slide39

Polytypism, twinning, and compositecrystals in MV4O8 (M = Y, Yb, Lu)

Average structure

Pnam

P121/n1 A21/d11

α-phase β-phase

slide40

Phasetransitions in MV4O8 (M = Y, Yb, Lu) at lowtemperatures

a-YV4O8

b-YV4O8

(a,b)-YV4O8

Q

Magnetic susceptibility Specific heat

Domain size effects: a ≈ 40-50 Å, b ≈ 500 Å

slide41

Guinier simulation of synchrotron powder diffraction data for b-YbV4O8

A21/d11 (Z = 4)

β-Phase

A21/d11 (Z = 4)

β’-Phase

180-185 K

ID31/ESRF

slide42

Isostructuralphasetransitions in a-YbV4O8 and b-YbV4O8

duetochargeordering at lowtemperatures (single-crystal data from ANKA & DESY)

α-phase β-phase

te

Temperature [K] Temperature [K]

slide43

High-pressurebehaviour of a-YbV4O8 and b-YbV4O8polytypes?

P121/n1, Z =4

A21/d11, Z =8

slide44

High-pressurebehaviour of a-YbV4O8 and b-YbV4O8polytypes?

P121/n1, Z =4

A21/d11, Z =8

(DAC)

SNBL/ESRF, PETRA III

(DAC)

SNBL/ESRF, PETRA III

(0.3 mm capillary)

ID31/ESRF

(0.3 mm capillary)

ID31/ESRF

a-YbV4O8 seems to be stable

at least to 16 GPa

b-YbV4O8 seems to be stable

at least to 10 GPa

slide45

Thefuture: an interplay of theeffects of a chemicalcomposition

and of highpressureonthestructuralstability and physicalproperties

of mixedvalencevanadates

►In situ high-pressure x-raystudies (diamondanvilcells and multi-anvils)

Phasetransitions

P-T phasediagrams

Chemicalreactions

►High-pressuresynthesis

►Physicalpropertiesunderhighpressures

Magnetism

Transportproperties

slide46

Collaborators

Karen Friese (JCNS, Jülich)

Yasushi Kanke (NIMS, Tsukuba)

Oleg Petracic (JCNS, Jülich)

Georg Roth (RWTH Aachen University)