## Abstract

A model for the thermal conductivity of bulk solids is proposed in the limit of diffusive transport mediated by diffusons as opposed to phonons. This diffusive thermal conductivity, κ_{diff}, is determined by the average energy of the vibrational density of states, ω_{avg}, and the number density of atoms, n. Furthermore, κ_{diff} is suggested as an appropriate estimate of the minimum thermal conductivity for complex materials, such that (at high temperatures):. A heuristic finding of this study is that the experimental ω_{avg} is highly correlated with the Debye temperature, allowing κ_{diff} to be estimated from the longitudinal and transverse speeds of sound: . Using this equation to estimate κ_{min} gives values 37% lower than the widely-used Cahill result and 18% lower than the Clarke model for κ_{min}, on average. This model of diffuson-mediated thermal conductivity may thus help explain experimental results of ultralow thermal conductivity.

Original language | English (US) |
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Pages (from-to) | 609-616 |

Number of pages | 8 |

Journal | Energy and Environmental Science |

Volume | 11 |

Issue number | 3 |

DOIs | |

State | Published - Mar 2018 |

## ASJC Scopus subject areas

- Environmental Chemistry
- Renewable Energy, Sustainability and the Environment
- Nuclear Energy and Engineering
- Pollution