A novel BN polymorph with ductile manner

A novel BN polymorph Pnc2 BN with sp2 hybridization is proposed and investigated in this work, which are mechanical stability and dynamical stability. The bulk modulus and shear modulus of Pnc2 BN are slightly greater than that of dz4 BN. The elastic anisotropy in shear modulus of Pnc2 BN is smaller than that of dz2 BN, dz4 BN, and lzlz2 BN, and the elastic anisotropy in Young's modulus of Pnc2 BN is smaller than that of dz4 BN and lzlz2 BN. The sound velocity of Pnc2 BN dz4 BN, and dz2 BN along [001], [010] and [100] propagation direction exhibit anisotropy. Compared with dz4 BN and dz2 BN, Pnc2 BN has the largest elastic anisotropy in sound velocity along [010] propagation direction. Among these four sp2 hybridization BN polymorphs, dz2 BN, dz4 BN, Pnc2 BN, and lzlz2 BN, only Pnc2 BN shows ductility. The Pnc2 BN is a semiconductor material with an indirect band gap of 3.543 eV calculated by using the Heyd-Scuseria-Ernzerhof (HSE06) functional. Finally, the x-ray diffraction (XRD) and Debye temperature of Pnc2 BN are also investigated. In future experimental studies, XRD characteristics may be very helpful in determining the crystal structure of Pnc2 BN.