Abstract:

The geometrical structures and nonlinear optical(NLO) properties of fourteen foreign-atom-doping (6,0) boron nitride nanotubes with B/N vacancy defect, M-V_a-BNNT(a=B and N; M=Li, Na, K, Be, Mg, Ca, C and Si), were investigated with the density functional theory(DFT) method. The computational results reveal that the B/N vacancy defect almost has no effect on the NLO properties of pristine boron nitride nanotube(BNNT). Compared with the BNNT with B vacancy defect, the foreign-atom doped at the N vacancy can more effectively increase the β₀ value of BNNT. The doping atom with the stronger reducing property in the same row can cause a larger improvement on the β₀ value of BNNT with N vacancy, namely, β₀(group Ⅰ)>β₀(group Ⅱ)>β₀(group Ⅳ). The reducing properties and atomic radius of the doping atoms in same family have a cooperation effect on the β₀ value of the BNNT, and the resulted case is that the doping Na and Mg atoms in the third row at N-vacancy can cause a larger β₀ value of the BNNT than the other atoms in the same family. These computational results will provide the new ideas and useful theoretical information for the designing of new type of high-performance NLO materials based on BNNTs.

Key words: Density functional theory, Boron nitride nanotube, Nonlinear optical, Vacancy defect, Doping