Improvement of power factor of n-type Bi^sub 2^Te^sub 3^ by dispersed nanosized Ga^sub 2^Te^sub 3^ precipitates

Inspired by the concept of energy filtering effect in improving the thermoelectric power factor (PF), we introduced a nanosized filter phase in an n-type Bi2Te3 bulk material. We selected Ga2Te3 as the filter phase because it has a suitable band offset at the conduction band minimum, as predicted by...

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Bibliographic Details
Published in:Journal of alloys and compounds 2017-12, Vol.726, p.578
Main Authors: Hazama, Hirofumi, Masuoka, Yumi, Yamamoto, Hidenari, Suto, Hiroyuki, Kinoshita, Yohei, Ishikiriyama, Mamoru, Asahi, Ryoji
Format: Article
Language:English
Subjects:
Annealing
Bismuth tellurides
Carrier density
Conduction bands
Dispersion
Effects
Electric power
Electrical equipment
Filtration
First principles
Grain boundaries
Power factor
Precipitates
Precipitation
Quenching
Quenching (cooling)
Sintering
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Summary:Inspired by the concept of energy filtering effect in improving the thermoelectric power factor (PF), we introduced a nanosized filter phase in an n-type Bi2Te3 bulk material. We selected Ga2Te3 as the filter phase because it has a suitable band offset at the conduction band minimum, as predicted by the first-principles calculations. We synthesized Bi2Te3 containing Ga2Te3 precipitates by carefully controlling the sintering and annealing temperatures, which followed the liquid-quenching process. It was found that the nanosized Ga2Te3 precipitates (~(100nm) improved the PF of n-type Bi2Te3, while the microsized Ga2Te3 did not. In particular, the homogeneously dispersed nanosized Ga2Te3 precipitates were better than the segregated Ga2Te3 at the grain boundaries in improving the PF. The obtained PF of Bi1.9Ga0.1Te3 at 300 K was 2.80 × 10-3 W/mK2, which is 60% higher than that of n-type Bi2Te3. The Jonker plot clearly showed that this improvement is far beyond the optimized value for the given carrier concentration.
ISSN:0925-8388
1873-4669