Unusual n-type thermoelectric properties of Bi2Te3 doped with divalent alkali earth metals
Abstract
Bi2Te3-based materials are a representative thermoelectric system operating near ambient temperature. Their n-type family is very limited and underperforms the p-type counterpart, which is a major concern in the thermoelectric community. Here we report that alkali earth metals (AE = Mg, Ca, Sr, Ba) in Group 2 unusually induce n-type thermoelectric properties in Bi2Te3. Mg is the most efficient electron donor among them. The x = 0.01 sample of MgxBi2-xTe3 (x = 0.005, 0.01, 0.015) system exhibits remarkably enhanced power factor and ZT of 0.8 at 350 K in comparison with pristine Bi2Te3. The improved performance is attributed to simultaneously enhanced electrical conductivity and reduced lattice thermal conductivity. Remarkably, MgxBi2-xTe3 materials show larger Seebeck coefficients than those expected by the theoretical Pisarenko relation.
- Publication:
-
Journal of Solid State Chemistry France
- Pub Date:
- January 2019
- DOI:
- 10.1016/j.jssc.2018.10.012
- Bibcode:
- 2019JSSCh.269..396B
- Keywords:
-
- Thermoelectric;
- Bismuth telluride;
- Alkaline earth metal doping;
- n-type conduction;
- Waste heat