prospective thermoelectric tellurides
DESCRIPTION
E2.1.8x6761. Prospective Thermoelectric Tellurides. Patrik Čermák University of Pardubice, Czech Republic. „Thermoelectrics as an ‘ energy gate ’ to deep space“. Space probes (e.g.): Voyager 1, 2 (1977) Galileo (1989) Ulysses (1990) Cassiny (1997) New Horizons (2006). - PowerPoint PPT PresentationTRANSCRIPT
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Prospective Thermoelectric Prospective Thermoelectric TelluridesTellurides
Patrik ČermákPatrik ČermákUniversity of Pardubice, Czech Republic
E2.1.8x6761
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„„Thermoelectrics as an Thermoelectrics as an ‘‘energy gateenergy gate’’ to deep space“ to deep space“
Space probes (e.g.):
• Voyager 1, 2 (1977)
• Galileo (1989)
• Ulysses (1990)
• Cassiny (1997)
• New Horizons (2006)
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I. Introduction to ThermoelectricsI. Introduction to Thermoelectrics
1. Seebeck effect 2. Peltier effect
Thermoelectric materials
• The main aim of researching of TE materials in general is enhance their efficiency in defined temperature range.
p-type n-type
U+ -
+++
---
Heating
Performance criterion for practical applications:
T
ZT2
TU ABAB TIQ
p-type n-type+++
---
- --
Cooling
Q
500 1000 15000
1
2
3
4
p - SiGe
ZT = 1
n - SiGe
p - Bi0.5
Sb1.5
Te3
n - PbTe
n - Bi2Te
2.95Se
0.05
Z*1
03 (K
-1 )
T ( K )
p - Ce Fe0.9
Co0.1
Sb3
p - Zn4Sb
3
500 1000 15000
1
2
3
4
p - SiGe
ZT = 1
n - SiGe
p - Bi0.5
Sb1.5
Te3
n - PbTe
n - Bi2Te
2.95Se
0.05
Z*1
03 (K
-1 )
T ( K )
p - Ce Fe0.9
Co0.1
Sb3
p - Zn4Sb
3
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II. ResearchII. Research
Motivation
1. Optimize of figure of merit ZT of n-type Bi2+xTe3-x-y-zSeyIz polycrystalline system for enhance of efficiency of Peltier elements in room temperature range (300 K).
2. Preparation of „novel TE material – GaGeTe“ with enhanced electrical conductivity (focuse on figure of merit ZT) and development of complementary n-type.
Characterization
• X-ray Diffraction
• Seebeck coefficient (Tc)
• Electrical conductivity c
• Thermal conductivity
• Hall coefficient RH (B║c)
Bi2Te3
c
a
Sb
Sb
Te 1
Te 1
Te 2
Te 2
Sb
Te 1
Te 1
Sb
Te 1
Bi
Bi
Bi
Bi
c
a
Sb
Sb
Te 1
Te 1
Te 2
Te 2
Sb
Te 1
Te 1
Sb
Te 1
Bi
Bi
Bi
Bi
GaGeTe
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III. ResultsIII. Results
Bi2+xTe3-x-y-zSeyIz
430 K
GaGeTe1-xIx
50 100 150 200 250 300 350 400 450
60
80
100
120
140
160
180
200
220
240
260
280
GaGeTe (no tempering) Bi
0,5Sb
1,5Te
2,9Se
0,1
(
V/K
)
T (K)
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IV. DiscussionIV. Discussion
Bi2+xTe3-x-y-zSeyIz
The samples with tetradymite structure were prepared. For optimization of TE properties (focused on figure of merit ZT) was examined the influence of iodine by doping classical Bismuth-Telluride (Bi2Te3).
Iodine +1-e than Tellurium increment of the concentration of free charge carriers: Substitution of „Te“ for „I“ - Bi2+xTe3-x-y-zSeyIz:
n
GaGeTe1-xIx
This (ternary) system show high Seebeck coefficient then the state-of-the-art materials.
Is it a p-type semiconductor n-type = more –e.
I have prepared substitute compound TeI4 and doped the GaGeTe.
XRD shows minimal content of other phases successful doping.
T
n
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V. ConclusionsV. Conclusions
Bi2+xTe3-x-y-zSeyIz
The character of the optimize TE material is possible to expect at Bi2Te2,9Se0,096I0,004 – lower concentration of iodine but also .
Now will follows the measurements of the other TE properties including „certainty“ identifications by XRD.
TeV
TeV
TeV
GaGeTe1-xIx
The first results promising great potential of this „novel ternary telluride“.
Will follows the continual research consists from: (1) increment value of iodine for development complementary n-type, (2) doping by another elements which can increment value of electrical conductivity (e.g. create defects of positive charge) and then optimized its TE efficiency (parameter ZT).
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Thank you for your attentionThank you for your attention
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References for this presentationReferences for this presentation
Image „Stargate SG-1“
[1] www.trekkies.cz
Images of the space probes
[2] www.nasa.gov, www.wikipedia.org
Image „Radioisotope Missions“
[3] www.thermoelectrics.caltech.edu
Patrik Čermák
E-mail: [email protected]