Claudia Felser from the Max-Planck Institute in Dresden presents the design and synthesis of new materials for efficient energy technologies at the BASF Science Symposium held on March 9th 2015 in Ludwigshafen, Germany. For more information see https://creator-space.basf.com/content/basf/creatorspace/en/events/symposium-ludwigshafen.past.html.

1. Design and synthesis of new materials for energy
technologies
Claudia Felser

2. Co-workers in Dresden and elsewhere
Dresden group
SPP 1386

3. The Philosophy:
The Rational Design

4. Concept
Goal: Directed Design of new
multifunctional materials
our tool box: the periodic table

5. The „Designer“-Material

6. Heusler compounds
Diamond ZnS Heusler XYZ C1b X2YZ L21
Graf T, Felser C, Parkin SSP, IEEE TRANSACTIONS ON MAGNETICS 47 (2011) 367
Graf T, Felser C, Parkin SSP, Progress in Solid State Chemistry Chemistry 39 (2011) 1

7. Semiconductors
and Solarcells

8. Materials: Ternary Semiconductors …
Heusler C1b
Zn
Cd
Li
1 + 2 + 5 = 8
2 + 6 = 8
S
P
Zincblende structure
• Semiconductors
• with the magic electron number 8
• MgAgAs Structure
• C1b -Half Heusler- or Nowotny-Juza
compounds
Graf, Felser, Parkin, Progress in Solid State Chemistry (2011)

9. Zhang et al Adv. Funct. Mater. 2012,
… High through put
DFT-calculations of 650 Heusler compounds
LiCuS
LiZnP
Kieven, Naghavi, Klenk, Felser, Gruhn, PRB 81, 075208 (2010)

10. 2.0eV
CdS substituted by LiCuS
Kieven et al., Phys. Rev. B 81, (2010) 075208
Ternary Semiconductors …

11. LiCuS instead of CdS
Ternary Semiconductors …
Synthesis: Li + CuS  LiCuS
alumina tubes and sealed silica tubes
Synthesis temperature:1000°C black
powder cubic structure
Synthesis temperature: 450-500°C
Beleanu, et al. to be published

12. Li1+xCu1-xS
Beleanu, et al., to be published
EgapLiCuS ~ EgapCdSe

13. Thermoelectric applications
and
Phase separation

14. Thermelectrics
Automotive (BMW & GM)
G. J. Snyder and E. S. Toberer. Nature Materials, 7 (2008) 105

15. Thermelectrics
n = charge carrier concentration
m* = charge carrier effective mass
µ = charge carrier mobility
G. J. Snyder and E. S. Toberer. Nature Materials, 7 (2008) 105
T
S
ZT
κ
σ2
=

16. P. H. Ngan, D. V. Christensen,G. J. Synder, L. T. Hung,S. Linderoth and N. Pryds. Phys.Status Solidi A. 2013, 9
The Materials

17. The Recipe
Mike Coey, Magnetism and Magnetic Materials

18. Diamond ZnS Heusler XYZ C1b X2YZ L21
3 + 5 = 83 + 5 = 8
Ga As
MgLi
1 + 2 + 5 = 8
As
Zr Ni
4 + 10 + 4 = 18
Sn

19. Typ M aterial Price in $/kg
(metals)
V-VI Bi2Te3 140
IV-VI PbTe 99
Zn4Sb3 Zn4Sb3 4
p-M nSi1.73 24
n-M g2Si0.4Sn0.6 18
Si0.80Ge0.20 660
Silicides
Si0.94Ge0.06 270
Skutterutides CoSb3 11
Half-Heusler TiNiSn 55
n/p-Clathrate Ba8Ga16Ge30 1000
w it hout Ba
Oxides p-NaCo2O4, 17
w it hout Na, O
Zintl Phasen p-Yb14M nSb11 92
Th3P4 La3-XTe4 160
State of the art and cost
Thermoelectric
100 200 300 400 500 600 700
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
n-typ
p-typ
TiFe0.15
Co0.85
Sb
TiFe0.3
Co0.7
Sb
Ti 0.6
Hf 0.4
Co 0.87
Ni 0.13
Sb
Zr0.5
Hf0.5
CoSb0.8
Sn0.2
Zr 0.25
Hf 0.75
NiSn 0.975
Sb 0.025
Zr0.5
Hf0.5
NiSn
Zr0.25Hf0.25Ti0.5NiSn
0.994Sb
0.006
Zr0.25Hf0.25Ti0.5NiSn
0.998Sb
0.002
FigureofmeritZT
Temperatur [°C]

20. T
S
ZT
κ
σ2
=
κ: thermal conductivity
T: absolute temperature
σ2
SPF =
Power factor
σ: electrical
conductivity
S:
Seebeck
coefficient
0
1
2
3
4
5
-1.0
-0.5
0.0
0.5
1.0
-0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8
0
5
10
15
20
25
NiTiSn
T=300 K
elec.conductivity
σ/τ[1019
(Ωms)-1
]
Seebeckcoeficient
S(T)[mVK-1
]
electrons
holes
Metall
Powerfactor
PF(T)[1010
W/(K2
s)]
Chemical potential δµ/ ∆Egap
Metall
doped semiconductors
Band gap
𝑆𝑆 𝜎𝜎2
κ
Key:
 Increase Seebeck
 Increase electrical conductivity
 Decrease thermal conductivity
Tunability

21. Strange semiconductors…
F. Yan et al. arXiv:1406.0872
TaIrGe

22. Thermal conductivities
G. J. Snyder and E. S. Toberer. Nature Materials, 7 (2008) 105
R. Asahi et al. J. Phys.: Cond. Mat. 20 (2008) 64227
K. Miyamoto et al. Appl. Phys. Express 1 (2008) 081901
VK Zaitsev et al. PRB 74 (2006) 045207
The challenge: low thermal conductivity, especially for p-type

23. -1.0 -0.5 0.0 0.5 1.0
-400
-200
0
200
400
SeebeckcoefficientS(µ)[µVK-1]
Chemical potentialµ[eV]
TiNiSn at 500K
Ouardi et al , Appl. Phys. Lett. 99 (2011) 152112.
Band engineering
0 100 200 300 400
0,0
0,1
0,2
0,3
0,4
0,5
NiZr0.5
Hf0.5
Sn
single crystal
ZT
Temperature T [K]
0 100 200 300 400
-400
-300
-200
-100
0
SeebeckcoefficientS(T)[µVK-1
]
Temperature T [K]
NiZr0.5
Hf0.5
Sn
single crystal

24. Band Gaps
Ouardi et al. , Phys. Rev. B 82 (2010) 085108

25. Stable nano structures
80 µm80 µm
1000°C,
2 weeks
Köhne, Felser, Graf, Elmers, Bosch, University Mainz, published 2011, US Patent 20,130,156,636
M. Schwall et al. Adv. Funct. Mater. 22 (2012) 1822

26. Substitution in Ti0.3Zr0.35Hf0.35NiSn
15
n-Typ
p-Typ
DFT CPA calculations
acceptor
EF
donor
M*= Sc
M*= V, Nb

27. Long term stability of TE properties n-type
Julia Krez, Benjamin Balke, Claudia Felser, Wilfried Hermes and Markus Schwind, submitted preprint arXiv:1502.01828, 2015

28. Ti0.3-xVxZr0.35Hf0.35NiSn
REM Measurements
Transport n-Typ
Charge carrier concentration
 Max. zT
1 @ 800K
x
x x
x
Krez et al. , to be submitted

29. Ti0.3-xScxZr0.35Hf0.35NiSn (x = 0.01-0.05)
Transport p-TypeREM measurements
 Max. zT
0.3 @ 700K
500µm
Krez et al., preprint arXiv:1502.01828, 2015

30. Band Gap Modelling
Schmitt et al. in collaboration with Jeff Snyder, Mater. Horiz., 2015, 2, 68
Estimation of the band gap for different n-type
and p-type HH compounds using
the Goldsmid–Sharp formula (Eg ~ 2eSmaxTmax) [eV]
p-type HH Zr1-xScxNiSn:
• large mobility difference between electrons and holes
explains the difference in the thermopower band gap
• between n-type and p-type
• high electron-to-hole weighted mobility ratio (~5)

31. p-type Heusler compounds Ti1−xHfxCoSb0.85Sn0.15
Main reflection (220) of Ti1−xHfxCoSb0.85Sn0.15
with the indicated ratios of Ti to Hf.
High resolution XRD
HfCoSb0.85Sn0.15
Rausch et al, submitted preprint arXiv:1502.03336

32. Enhanced thermoelectric
performance in the p-type
half-Heusler
(Ti/Zr/Hf)CoSb0.8Sn0.2
system via phase
separation
Rausch, Balke, Ouardi, Felser, Phys.Chem.Chem.Phys., 16 (2014), 25258.
100 200 300 400 500 600 700
1.0
1.5
2.0
2.5
3.0
3.5
4.0
100 200 300 400 500 600 700
0.0
0.2
0.4
0.6
0.8
1.0
(b)
PowerfactorS²σ[10-3
W/K²*m]
(a)
FigureofmeritZT
Temperature [°C]
Ti/Hf best TE-
properties !
Applying the concept of phase sep. to p-type

33. Charge carrier concentration optimization
The p-type Half-Heusler compound Ti0.3Zr0.35Hf0.35CoSb1−xSnx
1021
5x1021
1022
0
100
200
300
400
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
SebeckcoefficientS[µV/K]
S
Carrier concentration n [cm-3
]
@610 °C(b)
σS2
σ
κ
FigureofmeritZT
ZT
Rausch et al, to be published

34. p-type Heusler compounds Ti1−xHfxCoSb0.85Sn0.15
Rausch et al, submitted to Adv. Energy. Mater., preprint arXiv:1502.03336

35. p-type Heusler compounds Ti1−xHfxCoSb0.85Sn0.15
Rausch et al, submitted to Adv. Energy. Mater., preprint arXiv:1502.03336

36. 1021
2x1021
3x1021
4x1021
0
50
100
150
200
250
300
350
400
450
0.0
0.2
0.4
0.6
0.8
1.0
SebeckcoefficientS[µV/K]
S
Carrier concentration n [cm-3
]
@ 610 °C(b)
σ
S2
σ
κ
FigureofmeritZT
ZT
HfTi Ti0.5Hf0.5
Ti0.3Zr0.35Hf0.35CoSb1-xSnx
Open symbols
Ti1-xHfxCoSb0.85Sn0.15

37. Thermoelectric applications
and
Topological insulators

38. KF Hsu et al. Science 303 (2004) 819
Topological
Insulator
Yan, et al, PRB 85 (2012) 165125, arXiv:1104.0641
Yan et al. Phys. Status Solidi RRL 7 (2013) 13

39. Good TI are good thermoelectrics
Ouardi, et al., Appl. Phys. Lett. 99 (2011) 211904.
YPtBi
YPtBi

40. Topological insulators and thermoelectrics
Chandra Shekhar et. al. APL 100, 2152109 (2012).
Chandra Shekhar et al. PRB 86, 155314 (2012)
Chandra Shekhar et al., preprint arXiv:1502.04361
Zhipeng Hou et. al. arXiv:1502.03523

41. Properties
Graf, Felser, Parkin, IEEE TRANSACTIONS ON MAGNETICS 47 (2011) 367
Graf, Felser, Parkin, Progress in Solid State Chemistry 39 (2011) 1