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Main Authors: Cheng, Ruihuan, Wang, Chen, Ouyang, Niuchang, Shen, Xingchen, Chen, Yue
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2505.06926
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author Cheng, Ruihuan
Wang, Chen
Ouyang, Niuchang
Shen, Xingchen
Chen, Yue
author_facet Cheng, Ruihuan
Wang, Chen
Ouyang, Niuchang
Shen, Xingchen
Chen, Yue
contents Crystalline solids with extreme insulation often exhibit a plateau or even an upward-sloping tail in thermal conductivity above room temperature. Herein, we synthesized a crystalline material AgTl$_2$I$_3$ with an exceptionally low thermal conductivity of 0.21 $\rm W m^{-1} K^{-1}$ at 300 K, which continues to decrease to 0.17 $\rm W m^{-1} K^{-1}$ at 523 K. We adopted an integrated experimental and theoretical approach to reveal the lattice dynamics and thermal transport properties of AgTl$_2$I$_3$. Our results suggest that the Ag-I polyhedron enables extended antibonding states to weaken the chemical bonding, fostering strong lattice anharmonicity driven by the rattling vibrations of Ag atoms and causing lattice softening. Experimental measurements further corroborate the large atomic thermal motions and low sound velocity. These features impede particle-like phonon propagation, and significantly diminish the contribution of wave-like phonon tunneling. This work highlights a strategy for designing thermal insulating materials by leveraging crystal structure and chemical bonding, providing a pathway for advancing the development of thermal insulators.
format Preprint
id arxiv_https___arxiv_org_abs_2505_06926
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Strong Crystalline Thermal Insulation Induced by Extended Antibonding States
Cheng, Ruihuan
Wang, Chen
Ouyang, Niuchang
Shen, Xingchen
Chen, Yue
Materials Science
Crystalline solids with extreme insulation often exhibit a plateau or even an upward-sloping tail in thermal conductivity above room temperature. Herein, we synthesized a crystalline material AgTl$_2$I$_3$ with an exceptionally low thermal conductivity of 0.21 $\rm W m^{-1} K^{-1}$ at 300 K, which continues to decrease to 0.17 $\rm W m^{-1} K^{-1}$ at 523 K. We adopted an integrated experimental and theoretical approach to reveal the lattice dynamics and thermal transport properties of AgTl$_2$I$_3$. Our results suggest that the Ag-I polyhedron enables extended antibonding states to weaken the chemical bonding, fostering strong lattice anharmonicity driven by the rattling vibrations of Ag atoms and causing lattice softening. Experimental measurements further corroborate the large atomic thermal motions and low sound velocity. These features impede particle-like phonon propagation, and significantly diminish the contribution of wave-like phonon tunneling. This work highlights a strategy for designing thermal insulating materials by leveraging crystal structure and chemical bonding, providing a pathway for advancing the development of thermal insulators.
title Strong Crystalline Thermal Insulation Induced by Extended Antibonding States
topic Materials Science
url https://arxiv.org/abs/2505.06926