Modulating the thermal conductivity in hexagonal boron nitride via controlled boron isotope concentration

Hexagonal boron nitride (h-BN) has been predicted to exhibit an in-plane thermal conductivity as high as ~ 550 W m⁻¹ K⁻¹ at room temperature, making it a promising thermal management material. However, current experimental results (220–420 W m⁻¹ K⁻¹) have been well below the prediction. Here, we report on the modulation of h-BN thermal conductivity by controlling the B isotope concentration. For monoisotopic ¹⁰B h-BN, an in-plane thermal conductivity as high as 585 W m⁻¹ K⁻¹ is measured at room temperature, ~ 80% higher than that of h-BN with a disordered isotope concentration (52%:48% mixture of ¹⁰B and ¹¹B). The temperature-dependent thermal conductivities of monoisotopic h-BN agree well with first principles calculations including only intrinsic phonon-phonon scattering. Our results illustrate the potential to achieve high thermal conductivity in h-BN and control its thermal conductivity, opening avenues for the wide application of h-BN as a next-generation thin-film material for thermal management, metamaterials and metadevices.