1. Fluctuating bonding leads to glass-like thermal conductivity in perovskite rare-earth tantalates.
- Author
-
Che, Junwei, Liu, Xiangyang, Wang, Xuezhi, Zhang, Quan, Liang, Gongying, and Zhang, Shengli
- Subjects
- *
THERMAL conductivity , *TANTALATES , *PEROVSKITE , *THERMOELECTRIC materials , *CESIUM compounds , *PHONONS - Abstract
Understanding the glass-like thermal conductivity (κ) in simple-composition crystalline materials is critical for the development and design of low‒ κ materials. Here, we report the origin of glass-like low κ in binary crystalline tantalates RETa 3 O 9 (RE = Nd, Sm, Eu, Gd) by atomistic simulation. It is found that the low κ is mainly due to the rattling effect of RE3+ cations arising from the large difference in the interatomic bonding between O‒RE and O‒Ta. The vibrational mode decomposition results reveal that most modes in RETa 3 O 9 fall in the Ioffe–Regel regime and exhibit a strongly diffusive nature due to the fluctuating interatomic force of O‒Ta in the TaO 6 octahedron. The dual-phonon model reveals that the vast majority (>97%) of heat in RETa 3 O 9 is transported by diffusive modes rather than propagating modes. Consequently, the thermal conduction in RETa 3 O 9 exhibits a unique glass-like nature. Contrary to conventional belief, the optical phonon modes in RETa 3 O 9 play a significant role in thermal conduction. Overall, the new insight into the link between chemical binding and glass-like κ serves to the development and design of low‒ κ materials for thermoelectric and thermal management applications. [Display omitted] [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF