Modeling of new polymorphic varieties of boron nitride with the structure like structure of supercuban and rectangulan

The theoretical study of the structure and electronic properties of new polymorphic species of boron nitride BN-s and BN-r, which are structural analogues of the diamond-like carbon phases of supercuban and rectangulan, is carried out. The primary structures of these phases were modeled by replacing carbon atoms with boron and nitrogen atoms in the corresponding diamond-like phases, so that each atom of one type was bonded to three atoms of another type. Geometric optimization and investigation of the electronic properties of new boron nitride polymorphs were carried out in the framework of the density functional theory in the generalized gradient approximation. In addition to new boron nitride polymorphs, calculations were also performed for a number of BN polymorphs existing in nature — cubic BN-c, wurtzite-like BN-w and graphite-like BNg. The sublimation energy of new BN polymorphs BN-s and BN-r is 17.20 eV / (BN) and 17.87 eV / (BN), respectively. These values are lower than the sublimation energy of experimentally obtained boron nitride polymorphs: for cubic (BN-c) and graphitelike (BN-g) boron nitride, this value is 18.14 eV / (BN), and for wurtzite-like (BN-w) is 18.04 eV / (BN). However, a significant value of the sublimation energies of all the studied boron nitride polymorphs indicates the possibility of their stable existence under normal conditions. Boron nitride polymorphs with a structure similar to rectangulan and supercuban are wide-gap semiconductors with a band gap of 5.86 and 6.18 eV for BN-s and BN-r, respectively.