Thermoelectric Properties of the Bi2Te3 Compound Prepared by an Aqueous Chemical Method Followed by Hot Pressing

Bi2Te3 powders were synthesized at 453 K from Bi(NO3)3·5H2O and Te by an aqueous chemical method, then bulk material was fabricated by hot pressing at 673 K. To investigate the effect of microstructure on the transport properties of electrons and phonons, the thermoelectric performance of the hot-pressed sample and a zone-melted crystal with similar chemical composition was measured and compared. Strong grain-boundary scattering caused a significant decrease of the thermal conductivity; however, the maximum ZT value of the hot-pressed sample was 0.28, which was lower than that of the zone-melted crystal. Further improvement could be obtained through optimization of both chemical composition and microstructure.