A Ubiquitous Thermal Conductivity Formula for Liquids, Polymer Glass, and Amorphous Solids
Qing Xi1, Jinxin Zhong1, Jixiong He2, Xiangfan Xu1, Tsuneyoshi Nakayama1,3, Yuanyuan Wang4, Jun Liu2*, Jun Zhou1†*, and Baowen Li5*
1Center for Phononics and Thermal Energy Science, China-EU Joint Lab for Nanophononics, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China 2Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC 27695, USA 3Hokkaido University, Sapporo, Hokkaido 060-0826, Japan 4School of Environmental and Materials Engineering, Shanghai Polytechnic University, Shanghai 201209, China 5Paul M Rady Department of Mechanical Engineering, Department of Physics, University of Colorado, Boulder, CO 80305-0427, USA
Abstract：The microscopic mechanism of thermal transport in liquids and amorphous solids has been an outstanding problem for a long time. There have been several approaches to explain the thermal conductivities in these systems, for example, Bridgman's formula for simple liquids, the concept of the minimum thermal conductivity for amorphous solids, and the thermal resistance network model for amorphous polymers. Here, we present a ubiquitous formula to calculate the thermal conductivities of liquids and amorphous solids in a unified way, and compare it with previous ones. The calculated thermal conductivities using this formula without fitting parameters are in excellent agreement with the experimental data. Our formula not only provides a detailed microscopic mechanism of heat transfer in these systems, but also resolves the discrepancies between existing formulae and experimental data.
2020, Vol. 37 
