Pushing the Thermal Conductivity Limit by Decoupling Dual-Channel Phonon Transport in Crystals.
basic_science · Level V
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- Record sourced from PubMed, PMID 41355226.
- Also identified by DOI 10.1021/acs.nanolett.5c04725.
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Abstract
We propose a novel design principle for achieving ultralow thermal conductivity in crystalline materials via a "heavy-light and soft-stiff" structural motif. By combination of heavy and light atomic species with soft and stiff bonding networks, both particle-like (κ<sub><i>p</i></sub>) and wave-like (κ<sub><i>c</i></sub>) phonon transport channels are concurrently suppressed. First-principles calculations show that this architecture induces a hierarchical phonon spectrum: soft-bonded heavy atoms generate dense low-frequency modes that enhance scattering and reduce κ<sub><i>p</i></sub>, while stiff-bonded light atoms produce sparse high-frequency optical branches that disrupt the coherence and lower κ<sub><i>c</i></sub>. High-throughput screening identifies Tl<sub>4</sub>SiS<sub>4</sub> (κ<sub><i>p</i></sub> = 0.10, κ<sub><i>c</i></sub> = 0.06 W/mK) and Tl<sub>4</sub>GeS<sub>4</sub> (κ<sub><i>p</i></sub> = 0.09, κ<sub><i>c</i></sub> = 0.06 W/mK) as representative candidates with strongly suppressed transport in both channels. A minimal 1D triatomic chain model further demonstrates the generality of this mechanism, offering a new paradigm for phonon engineering beyond the conventional κ<sub><i>p</i></sub>-κ<sub><i>c</i></sub> trade-off.