Thermoelectric properties in the series Ag x TiS 2 Tristan Barbier, Marine Beaumale, Oleg Lebedev,...
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Transcript of Thermoelectric properties in the series Ag x TiS 2 Tristan Barbier, Marine Beaumale, Oleg Lebedev,...
Thermoelectric properties in the series AgxTiS2
Tristan Barbier, Marine Beaumale, Oleg Lebedev,
Emmanuel Guilmeau, Yohann Bréard, Antoine Maignan
Laboratoire CRISMAT, UMR6508 CNRS ENSICAEN, 6 bd du maréchal Juin, 14050 CAEN
ECT 2013 - ESA/ESTEC, Noordwijk
SummarySummary
Introduction
AgxTiS2 synthesis and sintering
Microstructure analysis
Thermoelectric properties
Conclusion
2
3
IntroductionIntroduction
This study is performed in the framework of InnovTEG project.
An innovative very low-cost thermo-electric technology for large-scalerenewable solar energy applications
The aim of this project is to create thermo-electric generators based on:
Low cost / abundant precursors
Low density of both compounds (n- p-types)Non-toxic elements
The purpose is 30 Wp/m² => ≈ 600€ / kWp (PV ≈ 3000€ / kWp)ZT ≈ 0.5 @ 100°C – T° range < 100°C - ∆T ≈ 30-80°C
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IntroductionIntroduction
*E. Guilmeau, Y. Bréard and A. Maignan, Applied Physics Letters 99, 052107 (2011)
In order to reach the full project specifications, TiS2 was chosen because :
Non-toxic precursors and final compound
Low price : 4.55 €/kg ( < 5.20 €/kg)
Abundant precursorsLow density : 3.24 g.cm-3
Currently, the best ZT value of TiS2 is around 0.20 @ 100°C - 0.37 @ 500°C*. => Improve the thermoelectric properties of TiS2.
Ag
=> AgxTiS2 with x = 0.02 ; 0.05 ; 0.1 and 0.2
Ti
Ti S
S
c
Bi2 T
e
3
Toxic
High density: 7.7 g.cm-3
Price: 40€/kg
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AgAgxxTiSTiS22 synthesis and sintering synthesis and sintering
Agx
TiS
Sealed silica tube
630°C12h
Muffle Furnace
Grind
Sieve
600°C30 min76 Mpa
SPS
Densities of the final pellets > 97%
All compounds with x < 0.2 contain only two phases Ag0.167TiS2 and TiS2
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Microstructure analysis : HR Microstructure analysis : HR XRDXRD
Platelet-like grains
(110
)(102
)
Modelling with isotropic crystallite size
(h,k < l)
(h,k > l)
Modelling with anisotropic crystallite size (00l)
(102
) (110
)
χ² = 5.89RBragg = 8.90
χ² = 3.00RBragg = 5.42
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Microstructure analysis : HR Microstructure analysis : HR XRDXRD
ISIE
M 2
01
3 – 2
7-3
1 O
ctober, R
ennes
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Thermoelectric properties Thermoelectric properties
All the thermoelectric properties were measured along the pressure direction
The resistivity and |S| values decrease showing that charge carriers concentration is increased by the Silver intercalation
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Thermoelectric propertiesThermoelectric properties
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Thermoelectric propertiesThermoelectric properties
Silver intercalation leads to an increase of the charge carriers concentration
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ConclusionConclusion
Decrease of the resistivityDecrease of Seebeck coefficient
Silver intercalation: creation of crystallographic disorder
Decrease of the thermal conductivity:
ZT values of x = 0.02 sample is higher than TiS2 in all the temperature range.
ProspectsProspects
Synthesis of compounds with lower content of silver (< 0.02) Synthesis of compounds with different cationic intercalation (Bi,
Co…)
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Acknowledgement
Thank you for your attention
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Microstructure analysis : HR XRD
(h,k < l)
(h,k > l)
When (h,k <l) the thickness of the plate-like is thin. => So the crystallization domain is lower than the theorical one. The real peak is more wide and less intense.
(00l)
h
k
l
(hk0)
(110
)(102
)
Modelling with isotropic crystallite size
(102
) (110
)
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Microstructure analysis : HR XRD
Microstrain calculation :1) Williamson et Hall
β cos (θ) = f ( sin (θ) ) β cos (θ)
sin (θ)
Slope = MicrostrainIntercep = Crystallite size
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Microstructure analysis : HR XRD
LaB6 refinement using Caglioti law
Creation of .IRF file => U, V, W, X, Y, Z = 0
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Microstructure analysis : HR Microstructure analysis : HR TEMTEM
Ag0.1TiS2
Ag0.2TiS2
Ag0.2TiS2