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.
Highlights
Bismuth (Bi) has been under investigations for a long time[1] due to its unique properties, e.g. its anisotropic transport properties, long charge carrier mean free path, large Fermi wavelength (70 nm) and semimetal band structure.[1,2,3,4,5,6,7] Bi bulk has a low thermoelectric performance,[1,8] given by the gure of merit ZT 1⁄4sS2T, where s is the electrical conductivity, S is the l absolute Seebeck coefficient and l is the thermal conductivity at a certain bath temperature T
The temperature-dependent thermal conductivity l of individual Bi-based nanowires was determined by the change of the resistance of the nanowires due to self-heating.[19]
A scanning transmission electron microscopy image (Fig. 1e) of a Bi/TiO2 nanowire placed on a carbon lm exhibits the growth direction
Summary
Bismuth (Bi) has been under investigations for a long time[1] due to its unique properties, e.g. its anisotropic transport properties, long charge carrier mean free path (up to a few hundred micrometers at 4 K), large Fermi wavelength (70 nm) and semimetal band structure.[1,2,3,4,5,6,7] Bi bulk has a low thermoelectric performance,[1,8] given by the gure of merit
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
