First-principles study on substituted doping of BN nanotubes by transition metals V, Cr and Mn

The substitution of a single boron atom or two atoms boron and nitrogen in (4,4) and (8,0) boron nitride nanotubes (BNNTs) by 3d transition metal (TM = V, Cr or Mn) atom has been systemically studied using first-principle calculations. All optimized TM-doped BNNT systems have obvious local deformation of the nanotubes, and almost all TM atoms protrude to the exterior of the wall. The substitution of TM atoms induces some impurity states within the band gaps of the pure BNNTs. The B site V-doped (4,4) BNNT system is half-metal while the BN1 site TM-doped (4,4) BNNT systems are metallicity. All the TM-doped (8,0) BNNT systems are still semiconductor. Overall charges are transferred from the TM atoms to more electronegative BNNTs. The substituted doping of TM atoms gives rise to magnetic moments which mainly stem from TM atoms. Therefore, the substitution of doping by TM enhances the chemical reactivity and significantly increases the conductivity of pure BNNT, and renders the TM-doped BNNT systems have larger magnetic moments. All these show the TM-doped BNNT systems have potential applications in hydrogen storage, gas sensing, catalysts, spintronics and magnetic data storage devices.