▎ 摘　　要

Carbon-doped boron nitride nanostructures including nanosheets, nanoribbons, and nanotubes have drawn enormous research attention because of their tunable electronic properties and widespread applications. In this work, we explore the electronic and magnetic properties of graphene flake-doped single-walled boron nitride nanotubes (BNNTs) on the basis of first-principles calculations. Theoretical results reveal that the band structures of these doped BNNTs can be effectively engineered by embedding graphene flakes with different sizes and shapes. Moreover, the Lieb theorem works for the triangle graphene flake-doped BNNTs, and the corresponding doped systems are ferromagnetic, originating from the spin-polarized interface states. All BNNTs embedded with the triangular graphene flakes with relatively small sizes are typical bipolar magnetic semiconductors, which can be easily tuned into half-metals by carrier doping, opening the door to their promising applications in spintronic devices.