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Thermodynamic study of iron-fluorine system
S. Chatain, M. Achour, Jl. Fleche, L. Martinelli
To cite this version:
S. Chatain, M. Achour, Jl. Fleche, L. Martinelli. Thermodynamic study of iron-fluorine system.
Colloque Francais de Chimie du Fluor 2017 (CFCF 2017), May 2017, Murol, France. 2017.
�hal-02419618�
Context and goals
CALPHAD (CALculation of PHAse Diagram) Method
Literature review
First principle calculations
Optimisation results
Further work
References
Thermodynamic study of iron-fluorine system
Sylvie Chatain
1, Mickaël Achour
2, Jean-Louis Flèche
1, Laure Martinelli
11
Den-Service de la Corrosion et du Comportement des Matériaux dans leur Environnement (SCCME) – CEA, Université Paris-Saclay, F-91919, Gif-sur-Yvette, France
2Hall de Recherche de Pierrelatte (HRP) – Division Chimie et Enrichissement, F-26701, Pierrelatte, France
Phase diagram
Thermodynamic properties
Solid Compounds
∆ ∆∆ ∆H°f ,298 K
(kJ/mol) Experimental method Reference
FeF2
-710.12 -715.5±0.5
Equilibrium pressure (2ndlaw) Equilibrium pressure (3rdlaw) [81Sch] -705.8±41.8 Equilibrium pressure [28Jel]
FeF3
-989.6±2.2 Calometric bomb [81Joh] -1037.6±4.5 F.e.m (3rdlaw) [81Sch]
-1056 -1043
Equilibrium pressure (3rdlaw) Equilibrium pressure (2ndlaw) [28Jel] -993 Equilibrium pressure (2ndlaw) [37Dom] -990.8±2.1 Calometric bomb [79Fer]
Computational method for calculating
multicomponent phase diagrams
Phase diagram = graphical representation of thermodynamic properties
⇒
Combination of
thermodynamics (Gibbs energies)
and
phase diagrams
data
Thermodynamic equilibrium at T, p, N
iis calculated by
minimizing the total Gibbs
energy G of the system
600 800 1000 1200 1400 0.67 0.69 0.71 0.73 0.75 Te m p e ra tu re ( °C ) XF Exp [73Tsi] FeF2 FeF3 liquid FeF2+FeF3 liq+FeF3 liq+FeF2
Lithium ion batteries (LIBs)
- FeF
3as electrode material, especially cathode
- effect of the nanostructure on
∆
G°
f⇒ nano CALPHAD
Iron corrosion in liquid UF
6(cf M. Achour poster)
- FeF
2and FeF
3as corrosion products
- improve the Fe-F thermodynamic description
- Fe-F database built using CALPHAD method
Only one experimental phase diagram determined by
Differential Thermal Analysis between FeF
2and FeF
3[73Tsi]
Discrepancies on the FeF
2melting temperature (950 °C [73Tsi],
975 °C [89Joh] or 1100 °C [98Cha])
No FeF
3fusion: sublimation without melting
-650 -640 -630 -620 -610 -600 -590 -580 -570 -560 500 600 700 800 900 1000 1100 1200 ∆ G °f ( Fe F2 , s ) (k J/ m o l) Temperature (K) [87Aza] [75Cha] [81Sch]
Good agreement for
∆
H°
f, 298 K(FeF
2, s) and
∆
G°
f, T(FeF
2, s)
∆
H°
f, 298 K(FeF
3, s) data scaterred
No thermodynamic properties for gaseous molecule Fe
2F
6and only
estimations for FeF
3Calculations on gaseous molecules performed using Density Functional Theory
implemented in DMol3 software
Generalized gradient approximation for exchange and correlation energy (GGA)
Spin of iron atoms taken into account
M : molecular weight
σ: symmetry number
IA, IBand IC, moment of inertia about principal axis
PV ) T ( E (T) E ) T ( E ) r ( E ) T (
H =coh i+ vib +rot +trans + r
(
)
(
)
[
]
RT PV 2 3 kT h exp 1 kT h exp h k R h 2 1 k R ) r ( E ) T ( H i i i i i i i coh + + ν − − ν − ν + ν + = r∑
∑
(
)
(
)
[
(
)
]
31482 . 2 P ln R M ln R 2 3 T ln R 2 5 Srot kT h exp 1 ln R kT h exp 1 kT h exp kT h R ) T ( S i i i i i i − − + + + ν − − − ν − − ν − ν =∑
∑
R 2 3 hc kT h cI 8 h cI 8 h cI 8 ln 2 R ) linear non ( S 3 C 2 B 2 A 2 rot + π π π σ π =(
)
(
)
(
)
[
]
R 2 5 R 2 3 kT h exp 1 kT h exp kT h R Cp i 2 i i 2 i + + ν − ν − ν =∑
Molecules ∆∆∆∆H°f, 298 K (kJ/mol) Reference FeF2 -387.9 This work -389.5 [98Cha] FeF3 -660.8 This work -820.9 [98Cha] Fe2F6 -1472.5 This workDTA experiments to check the phase diagram between FeF
2and FeF
3and between
Fe and FeF
2FeF
2fusion temperature measurement
Optimisation of the Fe-F system taken into account the new experimental data
Effect of the nanostructure of FeF
2and FeF
3on the phase diagram and
thermodynamic properties
Enlarge the study to Fe-O-F ternary system
[28Jel] K. Jellinek, A. Rudat, Z. Anorg. Allg. Chem. 175 (1928) p. 281-320 [37Dom] L. Domange, Ann. Chim. 7 (1937) p. 225
[73Tsi] T.G. Tsiklauri, E.G. Ippolitov, B.M. Zhigarnovskii, and S.V. Petrov, Soobshch Akad. Nauk. Gruz. SSR, 69 (1973) p. 593-596 [75Cha] G. Chattopadhyay, M.D. Karkhanavala, and S. Chandrasekharaiah, J. Electrochem. Soc. 122 (1975) p.325-327 [79Fer] G. Férey, A.M. Leclerc, R. de Pape, Solid State Communications 29 (1979) p. 477-480
[81Joh] G.K. Johnson, J. Chem. Thermodynamics 13 (1981) p. 465-469 [81Sch] S.C. Schaefer and N.A. Gokcen, High Temp. Science 14 (1981) p. 153-159 [89Joh] H.G. Johansen, A. Sterten and J. Thonstad, Acta Chem. Scand. 43 (1989) p. 417-420 [98Cha] M.W. Chase, NIST-JANAF Thermochemical Tables, (1998)
F e F3 F e F2 FeF2+liq FeF3+FeF2 FeF3+liq
