2024/05/30 by Yufeng Wang, Bo Sun, Wang, Yufeng +1
Materials Science · #Applied Physics (physics.app-ph) #Carbon Nanotubes in Composites #Diamond and Carbon-based Materials Research #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Thermal properties of materials
paper · pdf · doi:10.48550/arxiv.2405.19835
openalex publication_date 2024/05/30 · openalex created_date 2024/06/01 · openalex updated_date 2026/07/28
Diamond has the known highest thermal conductivity of around \SI2000\watt\per\meter\per\kelvin and is therefore widely used for heat dissipation. In practical applications, synthetic diamond microparticles are usually assumed to have similar thermal conductivity to that of bulk diamond because the particle size is larger than theoretical phonon mean free path so that boundary scattering of heat-carrying phonons is absent. In this report, we find the thermal conductivity of diamond microparticles anomalously depends on their sizes. Thermal conductivity of diamond microparticles increases from \SI400\watt\per\meter\per\kelvin to \SI2000\watt\per\meter\per\kelvin with the size growing from \SI20\micro\meter to \SI300\micro\meter. We attribute the abnormally strong size effect to the long-range defects during the growth process based on analysis of point defects, dislocations, and thermal penetration depth dependence of thermal conductivity. Our results play a vital role in the design of diamond composites and in the improvement of thermal conductivity of synthetic diamonds.