|About this Abstract
||2018 TMS Annual Meeting & Exhibition
||Computational Thermodynamics and Kinetics
||Thermoelectric Enhancement in Hybrid Ordered/Disordered Metamaterials via Phonon Localization and Band Anticrossing
||Taishan Zhu, Elif Ertekin
|On-Site Speaker (Planned)
We combine atomistic simulations and kinetic theory to show that a hybrid order/disordered silicon metamaterial leads to a phonon-glass-electron-crystal (PGEC). This metamaterial consists of a crystalline membrane decorated by regularly patterned disordered regions formed by ion beam irradiation. In these irradiated systems, the thermal conductivity is reduced by a factor of 20, while the power factor remains almost fully maintained, resulting in a figure of merit up to 0.5 at room temperature with doping concentration 3e19 cm^−3. To understand the reduction of thermal conductivity, we characterize all vibrational modes individually using lattice dynamics and molecular dynamics simulations. Spectral energy density analysis reveals phonon broadening due to defect scattering, thus reduction of phonon lifetimes. However, we find that defect scattering alone can only account for 15% of the overall reduction. Instead, using lattice dynamics and Allen-Feldman theory, we attribute the dominant suppression to the harmonic effects: phonon localization and band anti-crossing.
||Planned: Supplemental Proceedings volume