1. Prospective Thermoelectric Tellurides
E2.1.8x6761
Prospective Thermoelectric Tellurides
Patrik Čermák
University of Pardubice, Czech Republic

2. „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)

3. I. Introduction to Thermoelectrics
Seebeck effect Peltier effect
p-type
n-type U + -
Heating
p-type
n-type + -
Cooling Q
Thermoelectric materials
The main aim of researching of TE materials in general is enhance their efficiency in defined temperature range.
Performance criterion for practical applications:

4. II. Research Motivation Bi2Te3 Characterization GaGeTe
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).
Preparation of „novel TE material – GaGeTe“ with enhanced electrical conductivity s (focuse on figure of merit ZT) and development of complementary n-type.
Bi2Te3
Characterization
X-ray Diffraction
Seebeck coefficient a (Tc)
Electrical conductivity sc
Thermal conductivity k
Hall coefficient RH (B║c)
GaGeTe

5. III. Results
Bi2+xTe3-x-y-zSeyIz
GaGeTe1-xIx
430 K

6. IV. 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: T a n
Substitution of „Te“ for „I“ - Bi2+xTe3-x-y-zSeyIz: n s a a
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.

7. V. Conclusions Bi2+xTe3-x-y-zSeyIz GaGeTe1-xIx
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.
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).

8. Thank you for your attention

9. References for this presentation
Image „Stargate SG-1“
[1]
Images of the space probes
[2]
Image „Radioisotope Missions“
[3]
Patrik Čermák