Title: Phonon thermal transport through tilt grain boundaries in strontium titanate

Abstract

Here, we perform nonequilibrium molecular dynamics simulations to study phonon scattering at two tilt grain boundaries (GBs) in SrTiO₃. Mode-wise energy transmission coefficients are obtained based on phonon wave-packet dynamics simulations. The Kapitza conductance is then quantified using a lattice dynamics approach. The obtained results of the Kapitza conductance of both GBs compare well with those obtained by the direct method, except for the temperature dependence. Contrary to common belief, the results of this work show that the optical modes in SrTiO₃ contribute significantly to phonon thermal transport, accounting for over 50% of the Kapitza conductance. To understand the effect of the GB structural disorder on phonon transport, we compare the local phonon density of states of the atoms in the GB region with that in the single crystalline grain region. Our findings reflect that the excess vibrational modes introduced by the structural disorder do not have a significant effect on phonon scattering at the GBs, but the absence of certain modes in the GB region appears to be responsible for phonon reflections at GBs. This work has also demonstrated phonon mode conversion and simultaneous generation of new modes. Some of the new modes have the same frequency as themore » initial wave packet, while some have the same wave vector but lower frequencies.« less

Authors:

Zheng, Zexi ^[1]; Chen, Xiang ^[1]; Deng, Bowen ^[1]; Chernatynskiy, Aleksandr ^[1]; Yang, Shengfeng ^[1]; Xiong, Liming ^[1]; Chen, Youping ^[1]

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+ Show Author Affiliations

1. Univ. of Florida, Gainesville, FL (United States)

Publication Date:

Thu Aug 21 00:00:00 EDT 2014

Research Org.:

Energy Frontier Research Centers (EFRC) (United States). Center for Materials Science of Nuclear Fuel (CMSNF)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)

OSTI Identifier:

1369987

Grant/Contract Number:  

AC07-05ID14517; SC0006539

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Applied Physics

Additional Journal Information:

Journal Volume: 116; Journal Issue: 7; Related Information: CMSNF partners with Idaho National Laboratory (lead); Colorado School of Mines; University of Florida; Oak Ridge National Laboratory; Purdue University; University of Wisconsin at Madison; Journal ID: ISSN 0021-8979

Publisher:

American Institute of Physics (AIP)

Country of Publication:

United States

Language:

English

Subject:

42 ENGINEERING