title: Phonons, Localization, and Thermal Conductivity of Diamond Nanothreads and Amorphous Graphene.
abstract: Recently, the domains of low-dimensional (low-D) materials and disordered materials have been brought together by the demonstration of several new low-D, disordered systems. The thermal transport properties of these systems are not well-understood. Using amorphous graphene and glassy diamond nanothreads as prototype systems, we establish how structural disorder affects vibrational energy transport in low-dimensional, but disordered, materials. Modal localization analysis, molecular dynamics simulations, and a generalized model together demonstrate that the thermal transport properties of these materials exhibit both similarities and differences from disordered 3D materials. In analogy with 3D, the low-D disordered systems exhibit both propagating and diffusive vibrational modes. In contrast to 3D, however, the diffuson contribution to thermal transport in these low-D systems is shown to be negligible, which may be a result of inherent differences in the nature of random walks in lower dimensions. Despite the lack of diffusons, the suppression of thermal conductivity due to disorder in low-D systems is shown to be mild or comparable to 3D. The mild suppression originates from the presence of low-frequency vibrational modes that maintain a well-defined polarization and help preserve the thermal conductivity in the presence of disorder.
authors.affiliation: Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , 1206 W Green Street, Urbana Illinois 61801, United States.
authors.forename: Taishan
authors.initials: T
authors.lastname: Zhu
authors.affiliation: Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign , 1206 W Green Street, Urbana Illinois 61801, United States.|International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University , 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan.
authors.forename: Elif
authors.initials: E
authors.lastname: Ertekin
keywords: Phonons; diamond nanothreads; disorder; graphene; vibrational energy transport