摘要
Bulk n-type Bi2Te3 single crystals with optimized chemical composition were successfully prepared by a high temperature-gradient directional solidification method. We investigate the influence of alloy microstructure, chemical composition, and growth orientation on the thermoelectric transport properties. The results show that the composition of single-crystal Bi2Te3 alloy, along the c axis direction, could be slightly tuned by changing the growth rate of the crystal. At a rate of 18 mm/h, the formed Bi2Te3 crystal exhibits good thermoelectric properties. At 300 K, a maximum Seebeck coefficient of -245 μV/K and an electrical conductivity of 5.6 × 10 4 S/m are acquired. The optimal power factor is ob- tained as 3.3 × 10 -3 W/K2m, with a figure of merit of 0.74. It can be attributed to the increased tellurium allocation in the Bi2Te3 alloys, as verified well by the density functional theory caLculations.
Bulk n-type Bi2Te3 single crystals with optimized chemical composition were successfully prepared by a high temperature-gradient directional solidification method. We investigate the influence of alloy microstructure, chemical composition, and growth orientation on the thermoelectric transport properties. The results show that the composition of single-crystal Bi2Te3 alloy, along the c axis direction, could be slightly tuned by changing the growth rate of the crystal. At a rate of 18 mm/h, the formed Bi2Te3 crystal exhibits good thermoelectric properties. At 300 K, a maximum Seebeck coefficient of -245 μV/K and an electrical conductivity of 5.6 × 10 4 S/m are acquired. The optimal power factor is ob- tained as 3.3 × 10 -3 W/K2m, with a figure of merit of 0.74. It can be attributed to the increased tellurium allocation in the Bi2Te3 alloys, as verified well by the density functional theory caLculations.
基金
supported by the National Natural Science Foundation of China(Grant No.51074127)
the Research Fund of the State Key Laboratory of Solidification Processing of Northwestern Polytechnical University,China(Grant No.SKLSP201010)
