Choi Hyun Chul, Bae Seung Yong, Jang Woo Sung, Park Jeunghee, Song Ha Jin, Shin Hyun-Joon
Department of Chemistry, Korea University, Jochiwon 339-700, Korea.
J Phys Chem B. 2005 Apr 21;109(15):7007-11. doi: 10.1021/jp0464425.
Two boron nitride (BN) nanostructures, the bamboo-like nanotubes and nanothorns where the nanosize h-BN layers are randomly stacked looking like thorns, were synthesized selectively via thermal chemical vapor deposition of B/B(2)O(3) under the NH(3) flow at 1200 degrees C. Electron energy-loss spectroscopy reveals the N-rich h-BN layers with a ratio of B/N = 0.75-0.85. Angle-resolved X-ray absorption near edge structure of these two N-rich nanostructures has been compared with that of h-BN microcrystals. The pi transition in the N K-edge shifts to the lower energy by 0.8-1.0 eV from that of h-BN microcrystals, and the second-order signals of N 1s electrons become significant. We suggest that the N enrichment would decrease the band gap of nanostructures from that of h-BN microcrystals. The Raman spectrum shows the peak broadening due to the defects of N-rich h-BN layers.
通过在1200℃的NH₃气流下对B/B₂O₃进行热化学气相沉积，选择性地合成了两种氮化硼（BN）纳米结构，即竹节状纳米管和纳米刺，其中纳米尺寸的h-BN层随机堆叠，形似刺。电子能量损失谱显示富氮的h-BN层中B/N比为0.75 - 0.85。已将这两种富氮纳米结构的角分辨X射线吸收近边结构与h-BN微晶的进行了比较。N K边的π跃迁相对于h-BN微晶向低能方向移动了0.8 - 1.0 eV，并且N 1s电子的二阶信号变得显著。我们认为，富氮会使纳米结构的带隙比h-BN微晶的带隙减小。拉曼光谱显示由于富氮h-BN层的缺陷导致峰展宽。
