A unified understanding of minimum lattice thermal conductivity

Journal Article · Tue Jun 20 00:00:00 EDT 2023 · Proceedings of the National Academy of Sciences of the United States of America

DOI:https://doi.org/10.1073/pnas.2302541120· OSTI ID:1985949

Xia, Yi ^[1]; Gaines, II, Dale ^[2]; He, Jiangang ^[3]; Pal, Koushik ^[4]; Li, Zhi ^[2]; Kanatzidis, Mercouri G. ^[5]; Ozoliņš, Vidvuds ^[6]; Wolverton, Chris ^[2]

---

1. Department of Mechanical and Materials Engineering, Portland State University, Portland, OR 97201
2. Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208
3. School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083, China
4. Materials Science &, Technology Division, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545
5. Department of Chemistry, Northwestern University, Evanston, IL 60208, Materials Science Division, Argonne National Laboratory, Argonne, IL 60439
6. Department of Applied Physics, Yale University, New Haven, CT 06511, Energy Sciences Institute, Yale University, West Haven, CT 06516

We propose a first-principles model of minimum lattice thermal conductivity ( ${\kappa }_{\mathrm{L}}^{\min }$ ) based on a unified theoretical treatment of thermal transport in crystals and glasses. We apply this model to thousands of inorganic compounds and find a universal behavior of ${\kappa }_{\mathrm{L}}^{\min }$ in crystals in the high-temperature limit: The isotropically averaged ${\kappa }_{\mathrm{L}}^{\min }$ is independent of structural complexity and bounded within a range from ∼0.1 to ∼2.6 W/(m K), in striking contrast to the conventional phonon gas model which predicts no lower bound. We unveil the underlying physics by showing that for a given parent compound, ${\kappa }_{\mathrm{L}}^{\min }$ is bounded from below by a value that is approximately insensitive to disorder, but the relative importance of different heat transport channels (phonon gas versus diffuson) depends strongly on the degree of disorder. Moreover, we propose that the diffuson-dominated ${\kappa }_{\mathrm{L}}^{\min }$ in complex and disordered compounds might be effectively approximated by the phonon gas model for an ordered compound by averaging out disorder and applying phonon unfolding. With these insights, we further bridge the knowledge gap between our model and the well-known Cahill–Watson–Pohl (CWP) model, rationalizing the successes and limitations of the CWP model in the absence of heat transfer mediated by diffusons. Finally, we construct graph network and random forest machine learning models to extend our predictions to all compounds within the Inorganic Crystal Structure Database (ICSD), which were validated against thermoelectric materials possessing experimentally measured ultralow κ _L . Our work offers a unified understanding of ${\kappa }_{\mathrm{L}}^{\min }$ , which can guide the rational engineering of materials to achieve ${\kappa }_{\mathrm{L}}^{\min }$ .

• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0014520
• OSTI ID: 1985949
• Alternate ID(s): OSTI ID: 2404947
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Issue: 26 Vol. 120; ISSN 0027-8424
• Publisher: Proceedings of the National Academy of Sciences
• Country of Publication: United States
• Language: English