石墨烯硼氮類似物稱為白石墨烯,本論文乃以密度泛函中的B3LYP法研究含缺陷之以硼為邊氮為頂的白石墨烯三角形奈米薄片(BN-TNFn),其中n = 4~6為每邊六角環數目。由於薄片尚不夠大,在中央地區挖掉一個B或N原子後,結構重建的結果會因邊緣效應普遍呈現非平面。當半徑相近的C或O原子吸附在重建的破洞上方後,平面結構仍難回復,但C較具有縫補破洞的效果,O反而造成更大破洞或結構扭曲,這是因為C可與四個原子鍵結,O只能與兩個原子鍵結的緣故。如果直接將中心B或N換成雜質C或O情形也類似,只是C取代時平面變形較不嚴重;若換成O,反而從沒有破洞變成有破洞,而且造成去平面化。從平均結合能來看,破洞被吸附之後的產物比直接取代的產物還穩定。然而,不管是單單只有破洞、有雜質吸附在破洞、或直接取代,BN-TNFn的磁性都大大降低。
The boron nitride counterpart of graphene is the white graphene. In this thesis we employed the B3LYP method to investigate the B-edged (with N vertices) triangular nanoflakes of white graphene (BN-TNFn), where n = 4~6, being the number of hexagonal ring along each side. Because the area of BN-TNF4~6 are not wide enough, geometric reconstructions rendered non-planar species due to the edge effect after a vacancy was made by removing a central B or N atom. When an adatom C or O, which has similar sizes with B and N, was adsorbed by the reconstructed vacancy, the original flatness still could not be restored. However, C would stitch the hole, making it smaller, while O made the hole even larger and structure more distorted. This is because the bonding capacity of C and O are 4 and 2, respectively. Direct substitutions (doping) of a central B or N by C or O gave similar results. C-doping caused less structural distortion; however, O-doping opened a vacancy, making obvious structural changes. According to the mean binding energy, products from adatom adsorption were more stable than those from direct doping. Magnetism were greatly quenched by a vacancy, an adatom, and a dopant as compared to the pristine BN-TNF4~6.