Impact of surface phonons on the thermal conductivity of triply periodic minimal surface silicon

One of the core strategies for reducing the thermal conductivity of materials lies in effectively suppressing phonon transport. This study demonstrates that the thermal conductivity of silicon-based triply periodic minimal surface (TPMS) structures can be efficiently regulated through precise surface engineering. Specifically, the proportion of surface atoms and interface density in TPMS structures are controllable by adjusting the threshold parameter $c$ (a key geometric parameter that modulates the porosity of TPMS frameworks) and size parameter. Molecular dynamics simulation results indicate that TPMS structures reduce thermal conductivity, a phenomenon attributed to enhanced phonon-surface scattering. Surface phonons induce unique vibrational behaviors, including high-frequency localized modes, low-frequency phonon softening, and prominent boson-peak-like anomalies, and phonon participation ratio analysis confirms a direct correlation between strong phonon localization and surface atom density. Moreover, spectral thermal conductivity decomposition results further verify that surface phonons contribute negligibly to thermal conduction, while the core regions (with intact lattice) dominate heat transfer. These findings confirm that interaction between surface phonons and bulk phonons is the fundamental mechanism for thermal transport regulation in TPMS structures, providing a strategic pathway for designing functional thermal materials with on-demand customized thermal conductivity.