TY - JOUR
T1 - Vibrational Energy Transport in Hybrid Ordered/Disordered Nanocomposites
T2 - Hybridization and Avoided Crossings of Localized and Delocalized Modes
AU - Zhu, Taishan
AU - Swaminathan-Gopalan, Krishnan
AU - Cruse, Kevin J.
AU - Stephani, Kelly
AU - Ertekin, Elif
N1 - Funding Information:
The authors are grateful to M. I. Hussein from the University of Colorado at Boulder, and A. L. Goodwin from the Oxford University, for very patient and helpful discussions. They acknowledge financial support from the National Science Foundation under Grant No. EAGER-1550895. The authors acknowledge support from various computational resources: (i) the Blue Waters petascale computing facility, and (ii) the Illinois Campus Computing Cluster.
Publisher Copyright:
© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2018/4/25
Y1 - 2018/4/25
N2 - Vibrational energy transport in disordered media is of fundamental importance to several fields spanning from sustainable energy to biomedicine to thermal management. This work investigates hybrid ordered/disordered nanocomposites that consist of crystalline membranes decorated by regularly patterned disordered regions formed by ion beam irradiation. The presence of the disordered regions results in reduced thermal conductivity, rendering these systems of interest for use as nanostructured thermoelectrics and thermal device components, yet their vibrational properties are not well understood. Here, the mechanism of vibrational transport and the reason underlying the observed reduction is established in detail. The hybrid systems are found to exhibit glass-crystal duality in vibrational transport. Lattice dynamics reveals substantial hybridization between the localized and delocalized modes, which induces avoided crossings and harmonic broadening in the dispersion. Allen/Feldman theory shows that the hybridization and avoided crossings are the dominant drivers of the reduction. Anharmonic scattering is also enhanced in the patterned nanocomposites, further contributing to the reduction. The systems exhibit features reminiscent of both nanophononic materials and locally resonant nanophononic metamaterials, but operate in a manner distinct to both. These findings indicate that such “patterned disorder” can be a promising strategy to tailor vibrational transport through hybrid nanostructures.
AB - Vibrational energy transport in disordered media is of fundamental importance to several fields spanning from sustainable energy to biomedicine to thermal management. This work investigates hybrid ordered/disordered nanocomposites that consist of crystalline membranes decorated by regularly patterned disordered regions formed by ion beam irradiation. The presence of the disordered regions results in reduced thermal conductivity, rendering these systems of interest for use as nanostructured thermoelectrics and thermal device components, yet their vibrational properties are not well understood. Here, the mechanism of vibrational transport and the reason underlying the observed reduction is established in detail. The hybrid systems are found to exhibit glass-crystal duality in vibrational transport. Lattice dynamics reveals substantial hybridization between the localized and delocalized modes, which induces avoided crossings and harmonic broadening in the dispersion. Allen/Feldman theory shows that the hybridization and avoided crossings are the dominant drivers of the reduction. Anharmonic scattering is also enhanced in the patterned nanocomposites, further contributing to the reduction. The systems exhibit features reminiscent of both nanophononic materials and locally resonant nanophononic metamaterials, but operate in a manner distinct to both. These findings indicate that such “patterned disorder” can be a promising strategy to tailor vibrational transport through hybrid nanostructures.
KW - avoided crossing
KW - disorder
KW - metamaterials
KW - thermal property
KW - vibrational energy transport
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U2 - 10.1002/adfm.201706268
DO - 10.1002/adfm.201706268
M3 - Article
AN - SCOPUS:85042540292
VL - 28
JO - Advanced Functional Materials
JF - Advanced Functional Materials
SN - 1616-301X
IS - 17
M1 - 1706268
ER -