Phonon Transport within Periodic Porous Structures - From Classical Phonon Size Effects to Wave Effects

Yue Xiao1

Qiyu Chen1

Dengke Ma 2, 3

Nuo Yang 2, 4, Email

Qing Hao 1, Email

1 Department of Aerospace and Mechanical Engineering, University of Arizona, Tucson, AZ 85721 U.S.A

2 State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology (HUST), Wuhan 430074, China

3 NNU-SULI Thermal Energy Research Center (NSTER) & Center for Quantum Transport and Thermal Energy Science (CQTES), School of Physics and Technology, Nanjing Normal University, Nanjing 210023, China

4 Nano Interface Center for Energy(NICE), School of Energy and Power Engineering, Huazhong University of Science and Technology (HUST), Wuhan 430074, China

Abstract

Tailoring thermal properties with nanostructured materials can be of vital importance for many applications.  Generally classical phonon size effects are employed to reduce the thermal conductivity, where strong phonon scattering by nanostructured interfaces or boundaries can dramatically supress the heat conduction.  When these boundaries or interfaces are arranged in a periodic pattern, coherent phonons may have interference and modify the phonon dispersion, leading to dramatically reduced thermal conductivity.  Such coherent phonon transport has been widely studied for superlattice films and recently emphasized for periodic nanoporous patterns.  Although the wave effects have been proposed for reducing the thermal conductivity, more recent experimental evidence shows that such effects can only be critical at an ultralow temperature, i.e., around 10 K or below.  At room temperature, the impacted phonons are mostly restricted to hypersonic modes that contribute little to the thermal conductivity. In this review, the theoretical and experimental studies of periodic porous structures are summarized and compared.  The general applications of periodic nanostructured materials are further discussed.    

Phonon Transport within Periodic Porous Structures - From Classical Phonon Size Effects to Wave Effects