Abstract

Bi2Te3-based materials have been reported to be one of the best room-temperature thermoelectric materials, and it is a challenge to substantially improve their thermoelectric properties. Here novel Bi2Te3 core fibers with borosilicate glass cladding were fabricated utilizing a modified molten core drawing method. The Bi2Te3 core of the fiber was found to consist of hexagonal polycrystalline nanosheets, and polycrystalline nanosheets had a preferential orientation; in other words, the hexagonal Bi2Te3 lamellar cleavage more tended to be parallel to the symmetry axis of the fibers. Compared with a homemade 3-mm-diameter Bi2Te3 rod, the polycrystalline nanosheets’ preferential orientation in the 89-μm-diameter Bi2Te3 core increased its electrical conductivity, but deduced its Seebeck coefficient. The Bi2Te3 core exhibits an ultrahigh ZT of 0.73 at 300 K, which is 232% higher than that of the Bi2Te3 rod. The demonstration of fibers with oriented nano-polycrystalline core and the integration with an efficient fabrication technique will pave the way for the fabrication of high-performance thermoelectric fibers.

Highlights

  • Thermoelectric (TE) materials, which can directly convert waste heat to electrical energy or be used as Peltier refrigerators, are relevant to energy exploiting and power conservation.[1,2,3,4] The TE performance of materials is usually evaluated with a dimensionless figure of merit, ZT = S2σT /κ, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity.[5]

  • Bi2Te3-based nanowires/fibers can be prepared by using bottom-up deposition methods or top-down thermal drawing methods.[18,19,20,21,22,23,24,25]

  • The molten core thermal drawing method is more efficient for fabricating long lengths of TE core fibers

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Summary

Introduction

The axial thermal conductivity of the Bi2Te3 rod and Bi2Te3 fiber core was measured by the 3ω method using a homemade measuring apparatus, and the measuring details can be found in the supplementary material.

Results
Conclusion

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