Volume 59, Issue 12 pp. 4822-4829
Research Article

Intrinsically Low Thermal Conductivity and High Carrier Mobility in Dual Topological Quantum Material, n-Type BiTe

Manisha Samanta

Manisha Samanta

New Chemistry Unit, International Centre for Materials Science and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore, India

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Dr. Koushik Pal

Dr. Koushik Pal

Theoretical Sciences Unit, International Centre for Materials Science and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore, India

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Prof. Umesh V. Waghmare

Prof. Umesh V. Waghmare

Theoretical Sciences Unit, International Centre for Materials Science and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore, India

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Prof. Kanishka Biswas

Corresponding Author

Prof. Kanishka Biswas

New Chemistry Unit, International Centre for Materials Science and School of Advanced Materials, Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Jakkur P.O., Bangalore, India

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First published: 22 January 2020
Citations: 63

Graphical Abstract

Highs and lows: Intrinsically low lattice thermal conductivity (κlat) and high carrier mobility (μ) occurs in BiTe, which is facilitated by its unique dual topological quantum phases. It is a weak topological insulator (WTI) as a result of its layered hetero-structure, and thus it exhibits low thermal conductivity; but simultaneously BiTe is also a topological crystalline insulator (TCI) and thus it has high carrier mobility.

Abstract

A challenge in thermoelectrics is to achieve intrinsically low thermal conductivity in crystalline solids while maintaining a high carrier mobility (μ). Topological quantum materials, such as the topological insulator (TI) or topological crystalline insulator (TCI) can exhibit high μ. Weak topological insulators (WTI) are of interest because of their layered hetero-structural nature which has a low lattice thermal conductivity (κlat). BiTe, a unique member of the (Bi2)m(Bi2Te3)n homologous series (m:n=1:2), has both the quantum states, TCI and WTI, which is distinct from the conventional strong TI, Bi2Te3 (where m:n=0:1). Herein, we report intrinsically low κlat of 0.47–0.8 W m−1 K−1 in the 300–650 K range in BiTe resulting from low energy optical phonon branches which originate primarily from the localized vibrations of Bi bilayer. It has high μ≈516 cm2 V−1 s−1 and 707 cm2 V−1 s−1 along parallel and perpendicular to the spark plasma sintering (SPS) directions, respectively, at room temperature.

Conflict of interest

The authors declare no conflict of interest.

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