preparative methods in inorganic solid state chemistry · preparative methods in inorganic solid...
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Preparative Methods in Inorganic Solid State ChemistryLecture series given at the Department of Inorganic
Chemistry at University of Bonn, Germany (winter term 2014)
R. Glaum
Institut für Anorganische ChemieRheinische Friedrich-Wilhelms-Universität, Bonn (Germany)
http://www.glaum.chemie.uni-bonn.deemail: [email protected]
Contents
http://www.glaum.chemie.uni-bonn.de/
1. Basic ideas and problems about solid state reactions
2. Phase diagrams – Reading and understanding
3. Crystal Growth from a melt
4. Crystal Growth from a flux
5. Hydrothermal/solvothermal syntheses
7. Chemical Vapour Transport / Chemical Vapour Deposition
9. Commercial processes
8. Purification of Solids
6. Electrochemical Syntheses
Reactivity of Solids I.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
MgOs + Al2O3,s = MgAl2O4,s
interdiffusion layer, thickness x
= k · x –1dxdt
x = (k' · t) –1/2
parabolic growth
2Al3+ – 3Mg2+ + 4MgOs = MgAl2O4,s
Interface MgO / MgAl2O4:
3Mg2+ – 2Al3+ + 4Al2O3,s = 3 MgAl2O4,s
Interface MgAl2O4,s / Al2O3,s:
Overall reaction:
Spinel MgIIAlIII2O4
cubic, a = 8,081 Å; building units: [MgIIO4] and [AlIIIO6]
O2– Al/Cr3+ Mg2+
chromophor [CrO6]
http://www.glaum.chemie.uni-bonn.de/
M. C. Escher: Fishes to Birds
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1999.
Reactivity of Solids II.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
NiOs + Al2O3,s = NiAl2O4,s
= k · x –1dxdt
x = (k' · t) –1/2
parabolic growth
2Al3+ – 3Ni2+ + 4NiOs = NiAl2O4,s
Interface NiO / NiAl2O4:
3Ni2+ – 2Al3+ + 4Al2O3,s = 3 NiAl2O4,s
Interface NiAl2O4,s / Al2O3,s:
Overall reaction:formation of NiAl2O4,s
x2 = k'' · t
Wagner mechanism
Reactivity of Solids III.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Problems:high activation temperature required for migration (diffusion) of atoms (ions) in a solid low thermal stability of some reaction products
Solutions:application of high temperatures („shake and bake“; „heat and beat“; brute force methods)providing large surface areas and short diffusion paths for a solid state reaction to happenuse of reactive precursor materialsSolid state reactions via more mobile phases (liquid or gas phase: reactions in melts, hydrothermal synthesis, CVT)
An Example: Synthesis of Na3N
M. Jansen, Angew. Chem. 2002, 114, 3897.
Na3N: anti-ReO3 structure type
Problem:3Nal + 1/2N2,g ≠ Na3Nsvery high activation temperaturefor the starting materials low thermal stability of thereaction product (Tdecomp ≤ 360°C)
Solution:Intimidly mixed atoms have to bereacted!Co-condensation of Na- and N-atomsT = 4K, followed by slow heating
Synthesis of RuSb3
A. L. E. Smalley, M. L. Jespersen, D. C. Johnson, Inorg. Chem. 2004, 43, 2486.
RuSb3: metastable Skutterudite
Problem:Rus + 3 Sbs ≠ RuSb3,s high activation temperature
for the educts (Rus)
Rus + 3 Sbs = RuSb2,s + ¼ Sb4,g
m.p.(Sb) = 631°C; b.p.(Sb) = 1750°C
RuSb3,s + RuSb2,s + Sbs
Synthesis of RuSb3
A. L. E. Smalley, M. L. Jespersen, D. C. Johnson, Inorg. Chem. 2004, 43, 2486.
Structures of ReO3 and Skutterudite
Skutterudite: CoAs3ReO3
http://www.glaum.chemie.uni-bonn.de/
An example from „real life“ (1)
S.C. Roy, planned Ph. D. thesis, 2014, University of Bonn.J. J. Moore, H. J. Feng, Prog. Mater. Sciences 1995, 39, 243-273.
Synthesis of CrIII(WVIO2)2(P2O7)(PO4) with high specific surface area ( low-temperature synthesis)
Starting materials: (NH4)6W12O39∙5H2O, 6 Cr(NO3)3∙9H2O,18(NH4)2HPO4, glycine, HNO3
The concept: formation of a gel (coordinationpolymer) upon evaporation;Glycin & Ammonia (fuel) reactwith HNO3 (oxidant) in a com-bustion reaction; formation ofgaseous products and of a non-volatile, amorphous solid
Diffusion barrier: problem and chance in solid state chemistry
An example from „real life“ (1)
S.C. Roy, planned Ph. D. thesis, 2014, University of Bonn.
Keggin-type compound2 (NH4)3PW12O40 + „Cr12P34O85“
ReO3-type compound(CrIII
0.167WVI0.333PV
0.500)O2.500.5
WVOPO4-type compound(CrIII
0.333WVI0.667)OPO4
Complete crystal chemical differentiationCrIII(WVIO2)2(P2O7)(PO4)
Keggin-Anion [P(Mo3O10)4]3–
An example from „real life“ (1)
Keggin-type compound2 (NH4)3PW12O40
+„Cr12P34O85“
S. C. Roy, planned Ph.D. Thesis 2014; P. Armand, D. Granier, A. van der Lee, Acta Crystallogr. 2007, E63, i191.
Close the balance for all components!
Cr12W24P36Ox
ReO3
ReO2(PO4)
ReVIO3 (a = 3.46 Å)WVIO3 (a = 3.84 Å)(CrIII
0.167WVI0.333PV
0.500)O2.50.5 (a = 3.78 Å)(CrIII
0.10VIV0.10WVI
0.30PV0.500)O2.50.5 ?
(CrIII0.10VV
0.10WVI0.30PV
0.500)O2.50O0.050.45 ?
S. C. Roy, planned Ph.D. Thesis 2014; R. Glaum, S. Islam et. al., Z. anorg. allg. Chem. 2013, 639, 2463.
ReO3 type structures containing phosphate?
WVOPO4: a = 6.5538(4)Å, b = 5.2237(8)Å, c = 11.1866(8) Å, β = 90.332(7)°
(CrIII0.33WVI
0.67)OPO4: a = 6.473(1)Å, b = 5.1569(4) Å, c = 11.049(2) Å, β = 90.11(1)°
Structure of (CrIII0.33WVI
0.67)OPO4
(CrIII0.33WVI
0.67)OPO4:(CrIII
0.20VIV0.20WVI
0.60)OPO4 ?(FeIII
0.20VIV0.20WVI
0.60)OPO4 ?
S. C. Roy, planned Ph.D. Thesis 2014.
C2/m, Z = 16, a = 37.016(3) Å, b = 12.756(1) Å, c = 9.428(1) Å, β =102.275(9)°
Structure of CrIII(WVIO2)2(P2O7)(PO4)
S. C. Roy, planned Ph.D. Thesis 2014.
Homogeneity range for VIII(WVIO2)2(P2O7)(PO4): (W1−xVx)OPO4, 0.33 ≤ x ≤ 0.40
Gibbs Phase Triangles I.
Gibbs phase triangle for system Ti / P / O
http://www.glaum.chemie.uni-bonn.de/
Gibbs Phase Triangles II.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Ternary phase diagrams A / B / C showing differenthomogeineity regions
Gibbs Phase Triangles III.
Gibbs phase triangle for system Co / P / O(ϑ = 800°C)
A CoOB Co3(PO4)2C Co2P2O7D Co2P4O12E CoP4O11F P4O10G P4O6H Co2PI CoPJ CoP2K CoP3
II IV
I
V
VI
III
Co II :Co, Co3(PO4)2, Co2PCo IV:Co2P, Co2P2O7, CoP
http://www.glaum.chemie.uni-bonn.de/M. Blum, K. Teske, R. Glaum, Z. Anorg. Allg. Chem. 2003, 629, 1709.
Oxygen Coexistence Pressure I.
K.Teske, H. Ullmann, N. Trofimenko, J. Thermal Anal., 49 ( 1997 ) S.1211-1220
flux control ( 5l / h )
carrier gas : argon + 1000 ppm hydrogenup stream
celldown stream
cell
moisturizer (opt.)
reactorwith sample
coulometric / potentiometric determination of p(O2)
Oxygen Coexistence Pressure II.
MessprinzipA. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Oxygen Coexistence Pressure III.
Beispiel : CoIV (Co2P, Co2P2O7, CoP)
0,0008 0,0009 0,0010 0,0011
-24
-22
-20
-18
-16
-24
-22
-20
-18
-16
04. 02. 01Co4blm1; Auswertung mit I
log(
p(O
2))(p
(O2)
inat
m)
1/T [1/K]
log (p(O2))= 29.028 • 1/T + 7.614
http://www.glaum.chemie.uni-bonn.de/M. Blum, K. Teske, R. Glaum, Z. Anorg. Allg. Chem. 2003, 629, 1709.
Oxygen Coexistence Pressure IV.
1. What is the decomposition reaction?
2 / 7 Co2P2O7,s = 4 / 7 CoPs + O2,g
2. Thermodynamics :
∆rHT = (4/7∆fHT(CoPs) + ∆fHT(O2,g)) - 2/7 ∆fHT(Co2P2O7,s)
??
Van`t Hoff : RT
GK R∆−=ln
RS
RTHK RR ∆+
∆−=ln
http://www.glaum.chemie.uni-bonn.de/M. Blum, K. Teske, R. Glaum, Z. Anorg. Allg. Chem. 2003, 629, 1709.
Oxygen Coexistence Pressure V.
105329.0284.567
rH∆− = 10537,614
4.567rS∆
=
11053 132,6 kcal molRH −∆ = ⋅
1 11053 34,77 cal mol KrS − −∆ = ⋅ ⋅
CoP and Co2P2O7 are solids (a = 1), therefore Kp = p(O2)
than follows :log
4.567 4.567r rT T
pH S
KT
∆ ∆= − +
⋅
21
log (O ) 29.028 7.614pT
= − ⋅ +
comparison of coefficients yields:
and
eventually:
http://www.glaum.chemie.uni-bonn.de/M. Blum, K. Teske, R. Glaum, Z. Anorg. Allg. Chem. 2003, 629, 1709.
26
Cobaltoxide
homogeneity ranges of CoO(s) and Co3O4(s) are not includedCoO(s) melts at higher oxygen pressure, only Co2O3(s) is only badly characterised
Stability ranges of Co(s), CoO(s), and Co3O4(s) as functions of T and p(O2)
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
27
Oxygen co-existence pressures for binary systems I.
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
28
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
Oxygen Co-existence pressures for binary systems II.
29
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
Oxygen Co-existence pressures for binary systems III.
30
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
Oxygen Co-existence pressures for binary systems IV.
31
Metallo-thermic metal oxide reduction I.
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
Reduction of Fe2O3(s) by aluminium is no problem!
32
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
Reduction of HfO2(s) is impossible by aluminium but works with calcium!
Metallo-thermic metal oxide reduction II.
33
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
Ti1-xNbxO2 und Ti1-xSnxO2 sind möglich, Nb1-xSnxO2 nicht!
Mischkristallbildung TiO2, NbO2, SnO2
34
Redox behavior in a ternary system
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
cobalt(II) titanates(IV) are stabil, the combinations CoIII/TiIII, CoII/TiIII and CoII/TiII are not!
Simplification:components behave in the ternary system like the binaries!
35
Redox equilibria between oxides of iron and titanium
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
Only the combinations FeIII/TiIV and FeII/TiIV are stable!
36
Redox equilibria between oxides of iron and titanium
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
p(O2) rises from metallic titanium to iron(II) oxide.
I) II) III) IV)
sollid solutions:
FeIII2TiIV2O7
FeIII2TiIVO5
FeIITiIVO3FeII
2TiIVO4
37
Redox equilibria in the system Fe / V / O
P. Schmidt, Thermodynamische Analyse der Existenzbereiche fester Phasen – Prinzipiender Syntheseplanung in der Anorganischen Festkörperchemie, Habilitationsschrift,TU Dresden, 2007. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1200397971615-40549
In ternary oxides the combinations FeII/VIII, FeII,III/VIII,FeII,III/VIII,IV, FeIII/VIV and FeIII/VV are stable!
Phase Diagrams I.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
incongruentmelting of ABand varioussolid solutions
Phase Diagram MgO – Al2O3
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Crystal Growth Techniques I.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Czochralski Verneuil
pullingdirection
heater coil
crucible
growingcrystal
melt
O2 + powder
O2 + H2
flame
droplets
growing crystal
crystal support
(e.g.: Al2(SO4)3 + Cr2(SO4)3)
Verneuil‘s Technique
powder particels melt in the flame of an H2/O2 burner and crystallize on a crystal seedling; ruby and saphire are grown on an industrial scale applying Verneuil‘s technique
W. J. Moore, Der feste Zustand, Vieweg, 1977.
ca. 2
50 c
m
Synthetische Kristalle
Synthetische Kristalle besitzen die gleiche chemische Zusammensetzung wie natürlich gewachsene.
W. Schumann, „Edle Steine“, BLV Verlagsges. 1993.
Crystal Growth Techniques II.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Stockbarker Bridgman
zone melting
purification and crystallisation of metals
Flux Growth Techniques I.
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Reasons for application of the technique:
1) Desired material does not melt or has very high m.p.
2) Lowering of crystallization temperature
3) Improvement of crystal quality
4) Avoiding non-stoichiometry
Flux Growth Techniques II.
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Choice of a flux:
1) High solubility for desired compound
2) High temperature coefficient of solubility
3) No miscibility with the compound to be crystallized
4) Inertness towards dissolved material and crucible
Flux Growth Techniques III.
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Selected Examples - Oxides
Flux Growth Techniques IV.
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Means of achieving crystallization from fluxed melts:
EF: temperature gradient(transport)
A,B,C:slow cooling
AD: evaporation of solventOstwald-Miers-Region
Flux Growth Techniques V.
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Temperature profile (pendulum) for seed reduction:
Flux Growth Techniques VI.
B. R. Pamplin (ed.), Crystal Growth, Pergamon Press, 1975.
Modified flux growth
cfg. zone melting
Flux Growth Techniques VII.
K.-Th. Wilke, J. Bohm, Kristallzüchtung, DVW 1988.
elements, borides,carbides, pnictidesfrom metallic fluxes
Hydrothermal Synthesis I.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
tem
pera
ture
volumedensity
liquidphase
gas
phas
e
two phase
p, T diagramof water
critical point
Hydrothermal Synthesis II.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
p, T diagramof water
constant volume
various percen-tages % of fillingof an autoclave
Hydrothermal Synthesis III.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Solubilities under hydrothermal conditions1a) SiO2 – NaOH 450°C1b) SiO2 – Na2CO3 450°C2a) Al2O3 – NaOH 430°C2b) Al2O3 – Na2CO3 430°C3) LiGaO2 – NaOH 400°C4a) ZnO – NaOH 360°C4b) ZnO – KOH 360°C5a) ZnS – KOH 450°C5b) ZnS – KOH 360°C6) KTa0.65Nb0.35O3 – KOH
650°C
Hydrothermal Synthesis IV.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Steel autoclaves
Hydrothermal Synthesis V.
A. R. West, Solid State Chemistry and ist Applications, Wiley & Sons, 1984.
Solubilitiy of SiO2 in water (left) and NaOH (right)
temperature
solu
bilit
y
250 atm
500 atm
750 atm
1000 atm
0,5n NaOH (80% filling)
Hydrothermal Synthesis VI.
B. R. Pamplin, Crystal Growth, Pergamon Press, 1975.
α - β Transition for Quartz
H. Bärnighausen, Commun. Math. Chem. 1984, 9, 139.
Structural relationship
P 62 2 2
α-SiO2 ↔ β-SiO2, TT = 573°C (2nd order)
t2
P 32 2 1
Chemical Vapour Transport I.
http://www.glaum.chemie.uni-bonn.de/
Chemical Vapour Transport: Migration of an otherwise immobilesolid in a chemical potential gradient via a mobile phase (gas orliquid)
Migration in a temperature gradient
Cl2,g Fe2O3,s
transport agentT(source)
T(sink)
isothermal transport; short distance transport; mineralisation effects;hydrothermal syntheses
Chemical Vapour Transport II.
http://www.glaum.chemie.uni-bonn.de/
Chemical Transport Physical Transport(Destillation, Sublimation)
without transport agent
direction always from hot to cold(T2 6 T1)
needs a transport agent (but: autotransport)
migration from hot to cold (T2 6T1) as well as from cold to hot(T1 6 T2) possible
Applications:van Arkel / de Boer - Methodpurification of solidshalogen lampscrystal growthmineral formation / Geology
Applications:purification of solids and liquidsfreeze drying
Natural Hematite Fe2O3
http://www.glaum.chemie.uni-bonn.de/
Chemical Vapour Transport III.
http://www.glaum.chemie.uni-bonn.de/
Questions:
Cl2,g Fe2O3,s
transport agent
Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g “transport reaction”
Which solids can be “transported”?Optimum experimental conditions (TA; T)?Speed of the migration (deposition); migration rate?
transportingspecies
FeCl3,g; O2,g
Chemical Vapour Transport IV.
http://www.glaum.chemie.uni-bonn.de/
Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g “transport reaction”
The migration direction is determined by the sign of the reactionenthalpy of the transport reaction:
endothermic, ∆RHT > 0 Y T2 6 T1
exothermic, ∆RHT < 0 Y T1 6 T2(Def.: T1 < T2)
Examples: Oxides / chlorineChlorides, bromides / Al2X6
Si (Ti, Fe and other metals) / iodine
endotheric
exothermic
Estimation of the sign of the reaction enthalpy by consideration ofbond energies of educts and products
Thermodynamics
Chemical Vapour Transport V.
http://www.glaum.chemie.uni-bonn.de/
Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g “transport reaction”
“transport equilibrium”K
P FeCl P OP ClP =
⋅23
3 22
32
( ) ( )( )
/
(favorable: KP . 1; ∆RG . 0)
log ( ), ,
K TH
TS
PR T R T= −
⋅+
∆ ∆4 567 4 567
Gibbs-Helmholtz-equation∆ ∆ ∆R T R T R TG H T S= − ⋅(selection of T)
van t’Hoff-equation
Thermodynamics
Chemical Vapour Transport VI.
http://www.glaum.chemie.uni-bonn.de/
Experimental setting and definitions
ABK
ampoule dimensions: l . 11cm; q . 2,0 cm2; V . 22 cm3
V(source) : V(sink) . 2 : 1
Diffusion length s: 8 - 10 cm
SBK T(source)
T(sink)V(source)
V(sink)
Chemical Vapour Transport VII.
http://www.glaum.chemie.uni-bonn.de/
Calculation of partial pressures for CVT of Fe2O3,s using chlorine:
Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g
KP FeCl P O
P ClP =⋅2
33 2
23
2
( ) ( )( )
/
P(Cl2)T1, T2; P(FeCl3)T1, T2; P(O2)T1, T2; ΣPT1, T2 (8 unknown)
P FeCl P O( ) ( )343 2=
(2 Gl.)
(2 Gl.)
Σ PT1, T2 = P(Cl2)T1, T2 + P(FeCl3)T1, T2 + P(O2)T1, T2
n°(Cl2) = [(VT1/RT1)(P(Cl2)T1 + 3/2 P(FeCl3)T1] + [(VT2/RT2)(P(Cl2)T2 + 3/2 P(FeCl3)T2]
(2 Gl.)
Σ PT1 = Σ PT2
Chemical Vapour Transport VIII.
http://www.glaum.chemie.uni-bonn.de/
Partial pressure calculation for CVT of Fe2O3,s using chlorine:
Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g
P(Cl2)T1, T2; P(FeCl3)T1, T2; P(O2)T1, T2; ΣPT1, T2 (8 unknown pressures)
2 x -60,6
Exp. conditions: V = 22cm3; V(source) : V(sink) = 2 : 1 P°(Cl2) = 1 atm bei 298 K; n° = 0,982 mmol
3/2 x 0,03 x 0,0-196,82 x 82,2 3/2 x 49,03 x 53,320,9
∆RH298 = 75,6 [kcal / mol]
∆RS298 = 57,1 [cal / mol@K]
Chemical Vapour Transport IX.
http://www.glaum.chemie.uni-bonn.de/
Partial pressures as a function of temperature:
Ptotal P(Cl2) P(FeCl3) P(O2)T(source) T(sink)
Chemical Vapour Transport X.
http://www.glaum.chemie.uni-bonn.de/
Prerequisit for the application of the diffusion model:Diffusion between source and sink is the rate determining step of thewhole migration/deposition process
migration / deposition:(mechanism)
1.) Reaction of ABK with transport agent2.) evaporation of volatile species (1. phase transfer reaction)3.) “migration” from source to sink4.) seed formation5.) Crystal growth (2. phase transfer reaction)
Chemical Vapour Transport XI.
http://www.glaum.chemie.uni-bonn.de/
Transport formula derived by Harald Schäfer
, [ ],
nij
PP
T qs
D molAC= ⋅ ⋅
⋅⋅ ⋅ ⋅ −∆
Σ
0 8
0318 10
nA i, j
∆Pc
ΣP T q s
D0
Mole transported solid stoichiometric coefficients partial pressure difference [atm]
total pressure[atm] average temperature of diffusion path [K] cross section of diffusion path [cm2] length of diffusion path [cm] mean diffusion coefficient; 0,1 [cm2@sec-1]
Transport of Metals I.
http://www.glaum.chemie.uni-bonn.de/
Zrs + 4 Ig = ZrI4,g; 280 1450°C
Purification of Zirconium following van Arkel / de Boer:
(similarly: Ni, Cu, Fe, Cr, Si, Ti, Hf, Th, V, Nb, Ta, U)
Mos + 5/2 Cl2,g (5 Clg) = MoCl5,g; 400 1400°C
Ws + 3 Cl2,g (6 Clg) = WCl6,g; 400 1400°C
Nis + 4 COg = Ni(CO)4,g; 80 200°C
Purification of Nickel using the Mond-process:
(thermal stability of halogenide)
(vgl. H. Schäfer, Chemische Transportreaktionen, Verlag Chemie (1962))
Transport of Metals II.
http://www.glaum.chemie.uni-bonn.de/
e. g.: Ms + 2 Clg = MCl2,g; 800 1000°C
Transport of Fe and Ni using halogens (exothermic):
thermal instability of halides, e. g.:Rhs + 3/2 Cl2,g = RhCl3,g(s) (Y no transport)
Transport of noble metals:
(vgl. H. Schäfer et al., Z. anorg. allg. Chemie 286 (1956) 42.)
Transport of Fe and Ni using hydrogen halides (endothermic):e. g.: Ms + 2 HClg = MCl2,g + 2 H2,g; 1000 800°C
(vgl. H. Schäfer et al., Z. anorg. allg. Chemie 414 (1975) 137.)
increased volatility of halides by gas complex formation, e. g.:Rhs + 3/2 Cl2,g + Al2Cl6,g = RhAl2Cl9,g; 600 800°C
Transport of Oxides I.
http://www.glaum.chemie.uni-bonn.de/
Fe2O3,s + 3 Cl2,g = 2 FeCl3,g + 3/2 O2,g; 1000 900°C
Chlorine as transport agent:
Problem: a) frequently unfavourabel equilibria; b) transport of lower(stronly reducing oxides) is impossible Y Oxidation
TiO2,s + 2 Cl2,g = TiCl4,g + 2 O2,g; 900 800°C
MoO3,s + Cl2,g = MoO2Cl2,g + 1/2 O2,g; 900 800°C
Nb2O5,s + 3 Cl2,g = 2 NbOCl3,g + 3/2 O2,g; 1000 900°C
Solution: avoiding “free” oxygen; using non-oxidising transportagents (HCl, TeCl4, TaCl5, PI3)
Transport of Oxides II.
http://www.glaum.chemie.uni-bonn.de/
Fe2O3,s + 6 HClg = 2 FeCl3,g + 3 H2Og; 900 800°C
Non-oxidising transport agents:
Problems: occuring of solid (condensed) binary (halides) and ternary(tantalates; phosphates) phases
Ti3O5,s + 12 HClg = 3 TiCl4,g + 5 H2Og + H2,g; 900 800°C
MoO3,s + TeCl4,g = MoO2Cl2,g + TeOCl2,g; 900 800°C
Ta2O5,s + 3 TaCl5,g = 5 TaOCl3,g; 1000 900°C
3 TiO2,s + 4 PI3,g = 3 TiI4,g + P4O6,g; 900 800°C
Transport of Complex Oxides I.
http://www.glaum.chemie.uni-bonn.de/
CoNb2O6,s + 5/2 Cl2,g = CoCl2,g + NbOCl3,g + 5/2 O2,g
Transport behaviour similar to binary components:
lower solubility generally means lower solubility difference (lowermigration rate)
(Co1-xZnx)Os + Cl2,g = (1-x) CoCl2,g + x ZnCl2,g + 1/2 O2,g
Stabilisation of binary componenten by formation of the ternaryphase leeds to lower solubility in the gas phase of the ternary phasein comparison to the binary phases.
NiTiO3,s + 3 Cl2,g = NiCl2,g + TiCl4,g + 3/2 O2,g
Transport of Complex Oxides II.
http://www.glaum.chemie.uni-bonn.de/
ZnSO4,s + Cl2,g = ZnCl2,g + SO2,g + 1/2 O2,g
Chemical Vapour Transport of anhydrous sulfates:
Fe2(SO4)3,s + 3 Cl2,g = 2 FeCl3,g + 3 SO3,g + 3/2 O2,g
Fe2(SO4)3,s + 3 Cl2,g = 2 FeCl3,g + 3 SO2,g + 3 O2,g FeSO4,s + 2 HClg = FeCl3,g + SO2,g + H2Og + O2,g
(formation of Fe2O3,s)
NiSO4,s + Cl2,g = NiCl2,g + SO3,g + 1/2 O2,g
Al2(SO4)3,s + 3 SOCl2,g = 2 AlCl3,g + 6 SO2,g
2 VO(SO4)s + 3 Cl2,g = 2 VOCl3,g + 2 SO3,g + O2,g
NiSO4,s + PbCl2,g = PbSO4,s + 2 NiOs + SO2,g + Cl2,g
Transport of Halides I.
http://www.glaum.chemie.uni-bonn.de/
Caveat: migration in a temperature gradient frequently must be regarded as distillation or sublimation!
CrCl3,s + 1/2 Cl2,g = CrCl4,g; 800 700°C
MoBr3,s + MoBr5,g = 2 MoBr4,g; 475 250°C
Transport via higher halogenides (TR accompanied by oxidation):
(vgl. H. Schäfer, Z. anorg. allg. Chemie 414 (1975) 137.)
MoBr2,s + HgBr2,g = MoBr4,g; 1000 900°C
2 AlCl3,g = Al2Cl6,g
Transport via formation of gaseous complexes using AlCl3, AlI3,FeCl3 as complexing agent:
∆DimH298 = -30,1 [kcal / mol]; ∆DimS298 = -36,9 [cal / mol@K]
Transport of Halides II.
http://www.glaum.chemie.uni-bonn.de/
Dissoziation behaviour of Al2Cl6,g
(compare also dimerisation of CoCl2,g and other halides)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
400 600 800 1000 1200 1400 1600
temperature [K]
Al2Cl6,g
AlCl3,g
Transport of Halides III.
http://www.glaum.chemie.uni-bonn.de/
Transport of Halides IV.
http://www.glaum.chemie.uni-bonn.de/
Examples (synthesis of crystaline, anhydrous halogenides):
2 CrCl3,s + 3 Al2Cl6,g = 2 CrAl3Cl12,g
CoBr2,s + Al2Br6,g = CoAl2Br8,g; 400 300°C
( H. Schäfer et al., J. Less-Common Met. 61 (1978) 47.)
But:
CrCl2,s + Al2Cl6,g = CrAl2Cl8,g; 450 350°C
Pt (excess) + Br2,s + Al2Br6,g Y PtBr3,g; 400 350°C
Pd (excess) + I2,s + Al2I6,g Y Pd2Als + I2,g; T: 350 - 600°CTransport of Pd2Als: 375 600°C
( H. Schäfer, Angew. Chemie 88 (1976) 775.)
How to get metastable Solids?
When is a compound „stable“?
Synthetic pathways to metastable solids?
Zeolithe Mx/n[(AlO2)x(SiO2)y]·mH2O
Zeolithe Mx/n[(AlO2)x(SiO2)y]·mH2O
Zeolithe Mx/n[(AlO2)x(SiO2)y]·mH2O
[TO4]-Gruppen als Bausteine
Linde AUltramarin
Linde X/Y, FaujasitNa2Ca[Al4Si10O28]·20H2O4
Sodalith
β-Käfig
Ein molekularer Baukasten
Ein molekularer Baukasten
Löcher mit SiO2 drumherum
Linde A Linde X/Y, FaujasitNa2Ca[Al4Si10O28]·20H2O
Sodalith
Zeolithe besitzen Hohlräume, in die Moleküle oder Ioneneingelagert werden können.
Synthese von Zeolithen
SiO2haltige Verbindungenz.B. Wassergläser, Kieselsole
+ Natronlauge, Temperatur > 50°C, hydrothermale Reaktionsbedingungen
Zeolith
Al2O3haltige Verbindungenz.B. Aluminiumhydoxide, Aluminate, Kaoline
Anwendungen von ZeolithenEigenschaft Anwendung
AdsorptionIsolierglasKühlmittel
Dynamische Adsorption Trocknung und Reinigung von Erdgas, Spaltgas; Luftzerlegung
Trenneigenschaften Alkane / Isoalkane Trennung,
Ionenaustausch Waschmittel, Abwasserreinigung
Katalyse Fließbettcracken, Hydrocracken, Methanolumwandlung
Phosphates with Open Framework Structures
A. K. Cheetham, G. Férey, T. Loiseau, Angew. Chem. 1999, 111, 3466-3492.
VPI-5 (AlPO4)
M. E. Davis et al., Nature 1988, 331, 698.
~13 Å
Precipitation in the presence ofa structure dir-ecting reagent
Phosphates with Open Framework Structures
A. K. Cheetham et al., Chem. Commun. 2001, 859-860.
VSB-1 [Ni18(HPO4)14(OH)3F9(H3O/NH4)4 • 12 H2O
Effective catalyst for dehydrocyclodimerization of butadien!
Limited thermalstability of openframework structures!
Hydrothermal Synthesis of M2(H2P2O7)2
M. Blum, unpublished results, Univ. of Bonn, 2004.H. Thauern, Diploma Thesis, Univ. of Bonn, 2002.
M2(H2P2O7)2 = M2P4O12 + 2 H2O (M = Ni, Zn)2 M2(H2P2O7)2 = M(PO3)2 + 2 H2O (M = Zn)
Various Forms of FePO4
Y. Song, P. Y. Zavalij, M. Suzuki, M. S. Whittingham, Inorg. Chem. 2002, 41, 5778-5786.
Starting fromFePO4 • 2 H2O:
monoclinic and orthorhombicFePO4
[FeO6]
[FeO4]a
c
c
b
c
b
c
b
94
Aufbau eines Li-Ionen Akkumulators
M. Wohlfahrt-Mehrens, Zentrum für Sonnenenergie- und Wasserstoff-Forschung, Ulm.
Laden Entladen
Flüssige od. feste (Polymer) Elektrolyte
Alternative Elektroden-materialien?z.B.: LiFeIIPO4
Aufgeladen: CoIVO2 und LiC6
Entladen: LiCoIIIO2 und C6
Alternative Elektrolyte?
94
Various Forms of FePO4
A.S. Anderson, B. Kalska, L. Haggstrom, J. O. Thomas, Solid State Ionics 2000, 130, 41-52.
Delithiation of LiFePO4 (Olivine):preservation of thekinetically stable network structure
a
bmineralogy:(Fe1-xMnx)PO4 fromLi(Fe1-xMnx)PO4
new compounds:V2(PO4)3 fromLi3V2(PO4)3
Lithium batteries; electrode materials
The NASICON Structure Type
H. Kohler, H. Schulz, O.K. Mel'nikov, Mater. Res. Bull. 1983, 18, 1143-1152.
Sodium(Natrium) Super Ionic CONductor
[PO4] Tetrahedra[MO6] Octahedra
a
b
a
c
b
R 3 c; hcp array of [PO4] unitsβ-Fe2(SO4)3; NbIVNbV(PO4)3
e. g.: Na3.1Zr1.78 P1.76Si1.24O12
A. R. West, “Basic Solid State Chemistry”, 2nd ed., Wiley & Sons, 1999.
Intercalation / Deintercalation of Li
C. N. R. Rao & J. Gopalakrishnan, “New Directions in Solid State Chemistry”, Cambridge Univ. Press, 1986.
Intercalation / Deintercalation of Li
C. N. R. Rao & J. Gopalakrishnan, “New Directions in Solid State Chemistry”, Cambridge Univ. Press, 1986.