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arXiv · 2609.24191

Ultrahigh Thermal Conductivity in Isotopically Ultrapure Single-Crystal Diamond

Jinwen Liu·Junliang Fan·Zifeng Huang·Zhe Cheng
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Abstract

Diamond has the highest thermal conductivity among natural materials. Reducing isotope scattering can further push the limit of thermal conductivity of diamond. Here, we report the room-temperature thermal conductivity of a diamond single crystal with an exceptionally low ppm-level 13C content. Secondary ion mass spectrometry (SIMS) reveals a 13C concentration of only ~0.00024% and negligible other impurities, placing this sample as the most isotopically purified diamond samples reported to date. Time-domain thermoreflectance measurements show a room-temperature thermal conductivity of ~3100 W m-1 K-1. Although this value is markedly higher than that of natural diamond, it remains comparable to the best reported values for less isotopically 12C pure diamond. This result suggests that additional phonon-scattering mechanisms beyond isotope scattering may exist at this extreme isotopic purification level. Vacancy defects may contribute to the remaining suppression of thermal conductivity.

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Jinwen Liu, Junliang Fan, Zifeng Huang, Zhe Cheng. 2026-09-21. Ultrahigh Thermal Conductivity in Isotopically Ultrapure Single-Crystal Diamond. https://arxiv.org/abs/2609.24191

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