Abstract
The crystal chemistry of complex structured pavonite homologue Cux+yBi5−yS8 (1.2 ≤ x ≤ 1.4, 0.4 ≤ y ≤ 0.55) compounds with various crystallographic atomic sites was investigated in the context of their thermoelectric properties. We clarified the origins of the electronic and thermal transport properties of Cux+yBi5−yS8 compounds based on the change in the composition, which is strongly correlated with the occupancy of each atomic site. Ab initio calculations revealed that the narrow gap n-type semiconducting nature of Cux+yBi5−yS8 compounds originates from the presence of interstitial Cu ions. Structural refinements combined with transport measurements revealed that asymmetrical disorders of interstitial Cu ions have a large anisotropic thermal displacement factor, leading to an intrinsically low value (∼0.49 W m−1 K−1) and temperature-independent behavior of lattice thermal conductivity. Comprehensive structural analysis provided an elemental doping strategy focusing on interstitial sites. Thermoelectric properties were significantly enhanced by the simultaneous increase of power factor and decrease of lattice thermal conductivity. It is noted that structural factors, such as occupancy and thermal displacement parameter, of interstitial sites among the various crystallographic sites should be considered as primary characteristics in the crystal chemistry of complex structured crystals. Correspondingly, a peak ZT for the system was obtained in Cu1.576Zn0.024Bi4.6S8, which showed ∼30% enhancement over that of the pristine Cux+yBi5−yS8 compound.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: 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.