Self-reorganization of CdTe nanoparticles into two-dimensional Bi2Te3/CdTe nanosheets and their thermoelectrical properties

A partial cation exchange reaction between CdTe nanoparticles and Bi3+ ions gives rise to spontaneous formation of two-dimensional Bi2Te3/CdTe nanosheets. The average size and thickness of the nanosheets are around 200 and 6.9 nm, respectively. Both CdTe and Bi2Te3, which are there as the form of nanoparticles with average sizes of 3.4 nm, are found to be homogenously distributed in the nanosheets. The Bi2Te3/CdTe nanosheets are further integrated into a pellet by using spark plasma sintering for optimizing thermoelectric performance. Compared with the bulk n-type Bi2Te3, the pellets composed of Bi2Te3/CdTe nanosheets exhibit a considerably low thermal conductivity, 0.63 W m(-1) K-1, and a slightly high Seebeck coefficient, -182.2 mu V K-1, at room temperature.