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arXiv · 2401.16527

Ultra-low glassy thermal conductivity and controllable, promising thermoelectric properties in crystalline o-CsCu5S3

Jincheng Yue·Jiongzhi Zheng·Junda Li·Siqi Guo·Wenling Ren·Han Liu·Yanhui Liu·Tian Cui
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Abstract

We thoroughly investigate the microscopic mechanisms of the thermal transport in orthorhombic \textit{o}-CsCu$_5$S$_3$ by integrating the first-principles-based self-consistent phonon calculations (SCP) with the linearized Wigner transport equation (LWTE). Our methodology takes into account contributions to phonon energy shifts and phonon scattering rates from both three- and four-phonon processes. Additionally, it incorporates the off-diagonal terms of heat flux operators to calculate the total thermal conductivity. The predicted $\kappa_\mathrm{L}$ with an extremely weak temperature dependence following $\sim T^{-0.33}$, in good agreement with experimental values along with the parallel to the Bridgman growth direction. Such nonstandard temperature dependence of $\kappa_\mathrm{L}$ can be traced back to the dual particlelike-wavelike behavior exhibited by thermal phonons. Specifically, the coexistence of the stochastic oscillation of Cs atoms and metavalent bonding among interlayer Cu-S atoms limits the particle-like phonon propagation and enhances the wave-like tunneling of phonons. Simultaneously, the electrical transport properties are determined by employing a precise momentum relaxation-time approximation (MRTA) within the framework of the linearized Boltzmann transport equation (LBTE). By properly adjusting the carrier concentration, excellent thermoelectric performance is achieved, with a maximum thermoelectric conversion efficiency of 18.4$\%$ observed at 800 K in \textit{p}-type \textit{o}-CsCu$_5$S$_3$.} Our work not only elucidates the anomalous thermal transport behavior in the copper-based chalcogenide \textit{o}-CsCu$_5$S$_3$ but also provides insights for manipulating its thermal and electronic properties for potential thermoelectric applications.

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Jincheng Yue, Jiongzhi Zheng, Junda Li, Siqi Guo, Wenling Ren, Han Liu, Yanhui Liu, Tian Cui. 2024-01-29. Ultra-low glassy thermal conductivity and controllable, promising thermoelectric properties in crystalline o-CsCu5S3. https://doi.org/10.1021/acsami.4c02097

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