| Jan 24, 2026 |
Theta-phase tantalum nitride conducts heat nearly three times better than copper, opening new pathways for cooling electronics, AI, and quantum hardware.
(Nanowerk News) A UCLA-led, multi-institution research team has discovered a metallic material with the highest thermal conductivity measured among metals, challenging long-standing assumptions about the limits of heat transport in metallic materials.
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Led by Professor Yongjie Hu of the UCLA Samueli School of Engineering, the team reported that metallic theta-phase tantalum nitride (θ-TaN) conducts heat nearly three times more efficiently than copper or silver, the best conventional heat-conducting metals. The findings, verified through rigorous experiments and theoretical analysis, are published in Science (“Metallic θ-phase tantalum nitride has a thermal conductivity triple that of copper”).
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Hu, a leading expert in electronics thermal management, previously pioneered the 2018 experimental breakthrough of boron arsenide (Science, “Experimental observation of high thermal conductivity in boron arsenide”), another high-thermal-conductivity material, which set the world record for thermal conductivity in semiconductors and reshaped scientific understanding of heat transport in solids. The new θ-TaN result extends that record-breaking trajectory from semiconductors to metals.
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Thermal conductivity describes how efficiently a material can carry heat. Materials with high thermal conductivity are essential for removing localized hotspots in electronic devices, where overheating limits performance, reliability and energy efficiency. Copper currently dominates the global heat-sink market, accounting for roughly 30% of commercial thermal-management materials, with a thermal conductivity of about 400 watts per meter-kelvin.
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The UCLA-led team found that metallic theta-phase tantalum nitride, in contrast, has an ultrahigh thermal conductivity of approximately 1,100 W/mK, setting a new benchmark for metallic materials and redefining what is possible for heat transport in metals.
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Using ultrafast optical techniques, the researchers directly imaged how energy carried by electrons spreads through θ-TaN after the material is struck by a femto-second pulse of light, tracking the process from 0.1 to 10 picoseconds. These measurements revealed that excited electrons move rapidly while transferring remarkably little energy to the vibrating atoms of the crystal.
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| Experimental imaging of how energy, carried by electrons, spreads through theta-phase tantalum nitride after the metallic material is struck by a pulse of light, from 0.1 to 10 picoseconds. (Image: Courtesy of the researchers)
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“At a time when AI technologies advance rapidly, heat-dissipation demands are pushing conventional metals like copper to their performance limits, and the heavy global reliance on copper in chips and AI accelerators is becoming a critical concern,” said Professor Hu. “Our research shows that theta-phase tantalum nitride could be a fundamentally new and superior alternative for achieving higher thermal conductivity and may help guide the design of next-generation thermal materials.”
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For more than a century, copper and silver have represented the upper bound of thermal conductivity among metals. In metallic materials, heat is carried by both free-moving electrons and atomic vibrations known as phonons. Strong interactions between electrons and phonons and phonon-phonon interactions have historically limited how efficiently heat can flow in metals.
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The UCLA discovery demonstrates that this long-standing benchmark can be surpassed.
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Theoretical modeling suggested that theta-phase tantalum nitride could exhibit unusually efficient heat transport due to its unique atomic structure, in which tantalum atoms are interspersed with nitrogen atoms in a hexagonal pattern. The team confirmed the material’s performance using multiple techniques, including synchrotron-based X-ray scattering and ultrafast optical spectroscopy. These measurements revealed extremely weak electron–phonon interactions, enabling heat to flow far more efficiently than in conventional metals.
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Beyond microelectronics and AI hardware, the researchers say the discovery could impact a wide range of technologies increasingly limited by heat, including data centers, aerospace systems and emerging quantum platforms.
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Hu’s group has previously pioneered the experimental discovery of boron arsenide, and demonstrated high-performance thermal interfaces and gallium nitride devices integrating boron arsenide for cooling, highlighting the material’s promise for next-generation semiconductor technologies.
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Additional authors are from the U.S. Department of Energy’s Argonne National Laboratory, Lawrence Berkeley National Laboratory, Tohoku University, and Irvine Materials Research Institute.
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