Title: Giant anisotropic in-plane thermal conduction induced by Anomalous phonons in pentagonal PdSe₂

Abstract

In two-dimensional materials, different atomic stacking induces anisotropic atomic interactions and phonon dispersions, leading to the anisotropy of in-plane thermal transport. In this work, we report an exceptional case in layered pentagonal PdSe₂, where the bonding, force constants, and lattice constants are nearly-equal along the in-plane crystallographic axis directions, while the thermal conductivity is surprisingly much greater along b-axis than along a-axis with a ratio up to 1.8. Such strong anisotropy is not only unexpected in in-plane uniform structured materials, but also 2 comparable to the record high in-plane anisotropic thermal conductivity in the nonuniform structured material reported to date (the ratio is ~2.0 in TiS₃). By combining the inelastic X-ray scattering measurement and the first-principles calculations, we attribute such high anisotropy to the low-energy phonons along a-axis, particularly their lower group velocities and “avoided-crossing” behavior. The different buckling structures between a- (zigzag-type) and b-axis (flat-type) are mainly responsible for such unique phonon dynamics properties of PdSe₂. This finding helps to discover materials with high anisotropic in-plane thermal conductivity in uniform structures and reveals new physics of anisotropy of in-plane thermal conduction. Due to the unique features in structure and thermal transport properties, PdSe₂ may serve as a new platformmore » for designing novel devices to route heat flow precisely at the nanoscale.« less

Authors:

Wei, Bin  ^[1];

• Search DOE PAGES for author "Wei, Bin"
• Search DOE PAGES for ORCID "0000-0003-0125-1760"

Liu, Junyan ^[2]; Cai, Qingan ^[3]; Alatas, Ahmet  ^[4];

• Search DOE PAGES for author "Alatas, Ahmet"
• Search DOE PAGES for ORCID "0000-0001-6521-856X"

said, Ayman H. ^[4]; Hu, Meihua ^[5]; Li, Chen  ^[3];

• Search DOE PAGES for author "Li, Chen"
• Search DOE PAGES for ORCID "0000-0002-0758-5334"

Hong, Jiawang  ^[2]

• Search DOE PAGES for author "Hong, Jiawang"
• Search DOE PAGES for ORCID "0000-0002-9915-8072"

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+ Show Author Affiliations

1. Henan Polytechnic University, Jiaozuo (China); Beijing Institute of Technology (China)
2. Beijing Institute of Technology (China)
3. Univ. of California, Riverside, CA (United States)
4. Argonne National Lab. (ANL), Argonne, IL (United States)
5. Henan Polytechnic University, Jiaozuo (China)

Publication Date:

Thu Dec 23 00:00:00 EST 2021

Research Org.:

Argonne National Lab. (ANL), Argonne, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC); National Key Research and Development Program of China; National Natural Science Foundation of China (NSFC); Beijing Natural Science Foundation

OSTI Identifier:

1846427

Grant/Contract Number:  

AC02-06CH11357; 2021YFA1400300; 12172047; Z190011

Resource Type:

Accepted Manuscript

Journal Name:

Materials Today Physics

Additional Journal Information:

Journal Volume: 22; Journal ID: ISSN 2542-5293

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; anisotropy; thermal conductivity; phonon dispersion; inelastic x-ray scattering; PdSe₂