A tunable structural family with ultralow thermal conductivity: copper deficient Cu1-x□xPb1-xBi1+xS3

Maji, K., Lemoine, P., Renaud, A., Zhang, B., Zhou, X., Carnevali, V., Candolfi, C., Raveau, B., Al Orabi, R. A. R., Fornari, M., Vaqueiro, P. ORCID: https://orcid.org/0000-0001-7545-6262, Pasturel, M., Prestipino, C. and Guilmeau, E. (2022) A tunable structural family with ultralow thermal conductivity: copper deficient Cu1-x□xPb1-xBi1+xS3. Journal of the American Chemical Society, 144 (4). pp. 1846-1860. ISSN 0002-7863 doi: 10.1021/jacs.1c11998

Abstract/Summary

Understanding the mechanism that connects heat transport with crystal structures and order/disorder phenomena is crucial to develop materials with ultra-low thermal conductivity (K), for thermoelectric and thermal barriers applications and requires the study of highly pure materials. We synthesized the n-type sulfide CuPbBi5S9 with ultra-low K of 0.4-0.6 in the temperature range 300-700 K. In contrast to prior studies, we show that this synthetic sulfide is highly pure and does not exhibit the ordered gladite mineral structure but instead a copper-deficient partially disordered aikinite structure with Bi replacing Pb, according to the chemical formula Cu1/3□2/3Pb1/3Bi5/3S3. By combining experiments and lattice dynamics calculations, we elucidated that the ultra-low K of this compound is a result of combined structural disorder induced by the processing method and very low energy optical modes associated with Pb and Bi ions and, to a smaller extent, Cu. This vibrational complexity at low energy hints to substantial anharmonic effects that contributes to enhance phonon scattering. Importantly, we show that this aikinite sulfide, despite being a poor semiconductor, is a potential matrix for designing novel efficient n-type thermoelectric compounds with ultralow K. A drastic improvement of the carrier concentration and thermoelectric figure of merit have been obtained upon Cl for S and Bi for Pb substitution. The series Cu1-x□xPb1-xBi1+xS3 provide an interesting structural prototype for engineering n-type thermoelectric sulfides by controlling disorder and optimizing doping.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/102253
Identification Number/DOI	10.1021/jacs.1c11998
Refereed	Yes
Divisions	Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Publisher	American Chemical Society
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