Extremely Low Thermal Conductivity in Oxideswith Cage-Like Crystal Structure |
| |
Authors: | Michitaka Ohtaki So Miyaishi |
| |
Affiliation: | 1. Department of Molecular and Material Sciences, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1 Kasugakouen, Kasuga, Fukuoka, 816-8580, Japan
|
| |
Abstract: | Although successful examples of thermoelectric materials with the “rattler-in-a-cage” structure include filled skutterudites and clathrate compounds, there has been no report on “rattling” oxides. Here we report the thermal properties of defect pyrochlore (β-pyrochlore) oxides with smaller cations in an oversized cage-like crystal structure. It is clearly shown that the thermal diffusivity, α, and the thermal conductivity, κ, are lower for the oxides containing lighter A-site cations, contradicting the conventional prediction of the phonon thermal conductivity, in which lighter comprising atoms must give higher α and hence κ. These results strongly suggest that the smaller A-site cations with larger size mismatch to the surrounding cage structure enhance the phonon scattering and thereby reduce α and κ. These findings directly evidence the “rattling” effect of the loosely bound cations on the thermal transport properties of oxide materials. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|