Semimetal to semiconductor transition in Bi/TiO2core/shell nanowires

M. Kockert; R. Mitdank; H. Moon; J. Kim; A. Mogilatenko; S. H. Moosavi; M. Kroener; P. Woias; W. Lee; S. F. Fischer

doi:10.1039/d0na00658k

Semimetal to semiconductor transition in Bi/TiO₂core/shell nanowires

M. Kockert, R. Mitdank, H. Moon, J. Kim, A. Mogilatenko, S. H. Moosavi, M. Kroener, P. Woias, W. Lee, S. F. Fischer

Department of Materials Science and Engineering

Research output: Contribution to journal › Article › peer-review

1 Citation (Scopus)

Abstract

We demonstrate the full thermoelectric and structural characterization of individual bismuth-based (Bi-based) core/shell nanowires. The influence of strain on the temperature dependence of the electrical conductivity, the absolute Seebeck coefficient and the thermal conductivity of bismuth/titanium dioxide (Bi/TiO2) nanowires with different diameters is investigated and compared to bismuth (Bi) and bismuth/tellurium (Bi/Te) nanowires and bismuth bulk. Scattering at surfaces, crystal defects and interfaces between the core and the shell reduces the electrical conductivity to less than 5% and the thermal conductivity to less than 25% to 50% of the bulk value at room temperature. On behalf of a compressive strain, Bi/TiO2 core/shell nanowires show a decreasing electrical conductivity with decreasing temperature opposed to that of Bi and Bi/Te nanowires. We find that the compressive strain induced by the TiO2 shell can lead to a band opening of bismuth increasing the absolute Seebeck coefficient by 10% to 30% compared to bulk at room temperature. In the semiconducting state, the activation energy is determined to |41.3 ± 0.2| meV. We show that if the strain exceeds the elastic limit the semimetallic state is recovered due to the lattice relaxation.

Original language	English
Pages (from-to)	263-271
Number of pages	9
Journal	Nanoscale Advances
Volume	3
Issue number	1
DOIs	https://doi.org/10.1039/d0na00658k
Publication status	Published - 2021 Jan 7

Bibliographical note

Funding Information:
The authors thank D. Kojda and M. Albrecht for providing the electron beam-induced deposition process for the Bi/Te nano-wires. This work emerged from studies within the priority program “Nanostructured Thermoelectrics” SPP 1386 by the German Science Foundation (DFG). We gratefully acknowledge partial funding by DFG, partial nancial support by BMBF grant 01DR17012 and HU Berlin. This work was supported by the Agency for Defense Development, Republic of Korea (UD170089GD).

Publisher Copyright:
© The Royal Society of Chemistry.

All Science Journal Classification (ASJC) codes

Bioengineering
Atomic and Molecular Physics, and Optics
Chemistry(all)
Materials Science(all)
Engineering(all)

Access to Document

10.1039/d0na00658k

Cite this

@article{78a4ab7c5e5d4ccdbe933bb262cb7667,

title = "Semimetal to semiconductor transition in Bi/TiO2core/shell nanowires",

abstract = "We demonstrate the full thermoelectric and structural characterization of individual bismuth-based (Bi-based) core/shell nanowires. The influence of strain on the temperature dependence of the electrical conductivity, the absolute Seebeck coefficient and the thermal conductivity of bismuth/titanium dioxide (Bi/TiO2) nanowires with different diameters is investigated and compared to bismuth (Bi) and bismuth/tellurium (Bi/Te) nanowires and bismuth bulk. Scattering at surfaces, crystal defects and interfaces between the core and the shell reduces the electrical conductivity to less than 5% and the thermal conductivity to less than 25% to 50% of the bulk value at room temperature. On behalf of a compressive strain, Bi/TiO2 core/shell nanowires show a decreasing electrical conductivity with decreasing temperature opposed to that of Bi and Bi/Te nanowires. We find that the compressive strain induced by the TiO2 shell can lead to a band opening of bismuth increasing the absolute Seebeck coefficient by 10% to 30% compared to bulk at room temperature. In the semiconducting state, the activation energy is determined to |41.3 ± 0.2| meV. We show that if the strain exceeds the elastic limit the semimetallic state is recovered due to the lattice relaxation.",

author = "M. Kockert and R. Mitdank and H. Moon and J. Kim and A. Mogilatenko and Moosavi, {S. H.} and M. Kroener and P. Woias and W. Lee and Fischer, {S. F.}",

note = "Funding Information: The authors thank D. Kojda and M. Albrecht for providing the electron beam-induced deposition process for the Bi/Te nano-wires. This work emerged from studies within the priority program “Nanostructured Thermoelectrics” SPP 1386 by the German Science Foundation (DFG). We gratefully acknowledge partial funding by DFG, partial nancial support by BMBF grant 01DR17012 and HU Berlin. This work was supported by the Agency for Defense Development, Republic of Korea (UD170089GD). Publisher Copyright: {\textcopyright} The Royal Society of Chemistry.",

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doi = "10.1039/d0na00658k",

language = "English",

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T1 - Semimetal to semiconductor transition in Bi/TiO2core/shell nanowires

AU - Kockert, M.

AU - Mitdank, R.

AU - Moon, H.

AU - Kim, J.

AU - Mogilatenko, A.

AU - Moosavi, S. H.

AU - Kroener, M.

AU - Woias, P.

AU - Lee, W.

AU - Fischer, S. F.

N1 - Funding Information: The authors thank D. Kojda and M. Albrecht for providing the electron beam-induced deposition process for the Bi/Te nano-wires. This work emerged from studies within the priority program “Nanostructured Thermoelectrics” SPP 1386 by the German Science Foundation (DFG). We gratefully acknowledge partial funding by DFG, partial nancial support by BMBF grant 01DR17012 and HU Berlin. This work was supported by the Agency for Defense Development, Republic of Korea (UD170089GD). Publisher Copyright: © The Royal Society of Chemistry.

PY - 2021/1/7

Y1 - 2021/1/7

N2 - We demonstrate the full thermoelectric and structural characterization of individual bismuth-based (Bi-based) core/shell nanowires. The influence of strain on the temperature dependence of the electrical conductivity, the absolute Seebeck coefficient and the thermal conductivity of bismuth/titanium dioxide (Bi/TiO2) nanowires with different diameters is investigated and compared to bismuth (Bi) and bismuth/tellurium (Bi/Te) nanowires and bismuth bulk. Scattering at surfaces, crystal defects and interfaces between the core and the shell reduces the electrical conductivity to less than 5% and the thermal conductivity to less than 25% to 50% of the bulk value at room temperature. On behalf of a compressive strain, Bi/TiO2 core/shell nanowires show a decreasing electrical conductivity with decreasing temperature opposed to that of Bi and Bi/Te nanowires. We find that the compressive strain induced by the TiO2 shell can lead to a band opening of bismuth increasing the absolute Seebeck coefficient by 10% to 30% compared to bulk at room temperature. In the semiconducting state, the activation energy is determined to |41.3 ± 0.2| meV. We show that if the strain exceeds the elastic limit the semimetallic state is recovered due to the lattice relaxation.

AB - We demonstrate the full thermoelectric and structural characterization of individual bismuth-based (Bi-based) core/shell nanowires. The influence of strain on the temperature dependence of the electrical conductivity, the absolute Seebeck coefficient and the thermal conductivity of bismuth/titanium dioxide (Bi/TiO2) nanowires with different diameters is investigated and compared to bismuth (Bi) and bismuth/tellurium (Bi/Te) nanowires and bismuth bulk. Scattering at surfaces, crystal defects and interfaces between the core and the shell reduces the electrical conductivity to less than 5% and the thermal conductivity to less than 25% to 50% of the bulk value at room temperature. On behalf of a compressive strain, Bi/TiO2 core/shell nanowires show a decreasing electrical conductivity with decreasing temperature opposed to that of Bi and Bi/Te nanowires. We find that the compressive strain induced by the TiO2 shell can lead to a band opening of bismuth increasing the absolute Seebeck coefficient by 10% to 30% compared to bulk at room temperature. In the semiconducting state, the activation energy is determined to |41.3 ± 0.2| meV. We show that if the strain exceeds the elastic limit the semimetallic state is recovered due to the lattice relaxation.

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