Thermoelectric properties in the series Ag x TiS 2 Tristan Barbier, Marine Beaumale, Oleg Lebedev, Emmanuel Guilmeau, Yohann Bréard, Antoine Maignan [email protected].

Thermoelectric properties in the series AgxTiS2

Tristan Barbier, Marine Beaumale, Oleg Lebedev,

Emmanuel Guilmeau, Yohann Bréard, Antoine Maignan

[email protected]

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

9

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