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

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


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 languageEnglish
Pages (from-to)263-271
Number of pages9
JournalNanoscale Advances
Issue number1
Publication statusPublished - 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)


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