Preparative Methods in Inorganic Solid State Chemistry Lecture series given at the Department of Inorganic Chemistry at University of Bonn, Germany (winter term 2014) R. Glaum Institut für Anorganische Chemie Rheinische Friedrich-Wilhelms-Universität, Bonn (Germany) http://www.glaum.chemie.uni-bonn.de email: [email protected]
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Preparative Methods in Inorganic Solid State Chemistry · Preparative Methods in Inorganic Solid State Chemistry Lecture series given at the Department of Inorganic Chemistry at University
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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)
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)
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.
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.
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)
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]
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.