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 similar to 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 B-10 h-BN, an in-plane thermal conductivity as high as 585 W m(-1) K-1 is measured at room temperature, similar to 80% higher than that of h-BN with a disordered isotope concentration (52%:48% mixture of B-10 and B-11). 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.