CAJ | 학술논문

N是金刚石中的主要杂质之一,为了研究金刚石生长过程中杂质N对C电子结构转化的影响,用密度泛函理论研究了Ni(111)表面上C与N共吸附的三个不等价模型,同时建立了三个C吸附模型作为比较.计算结果表明,N原子的出现使得吸附体系相对不稳定,吸附原子之间的相互作用不能忽略;通过比较相互作用能可以看出,相同的吸附位下C-C相互作用比C-N相互作用强.通过比较不同模型中C原子分波态密度可以看出,N-C相互作用一定程度上增加了Ni的催化活性,但是与C-C自身的相互作用比较起来效果并不明显.吸附几何结构和分波态密度还表明,当吸附的原子过于紧密以致占有同-个Ni(111)-(1×1)晶胞表面时,就会形成CN化合物或者类石墨杂质.
N시금강석중적주요잡질지일,위료연구금강석생장과정중잡질N대C전자결구전화적영향,용밀도범함이론연구료Ni(111)표면상C여N공흡부적삼개불등개모형,동시건립료삼개C흡부모형작위비교.계산결과표명,N원자적출현사득흡부체계상대불은정,흡부원자지간적상호작용불능홀략;통과비교상호작용능가이간출,상동적흡부위하C-C상호작용비C-N상호작용강.통과비교불동모형중C원자분파태밀도가이간출,N-C상호작용일정정도상증가료Ni적최화활성,단시여C-C자신적상호작용비교기래효과병불명현.흡부궤하결구화분파태밀도환표명,당흡부적원자과우긴밀이치점유동-개Ni(111)-(1×1)정포표면시,취회형성CN화합물혹자류석묵잡질.
Nitrogen is a common impurity found in diamonds. We used three nonequivalent models to study carbon and nitrogen coadsorption on Ni(111) surface. Density functional theory (DFT) calculations were performed to study the influence of nitrogen upon the transformation of carbon's electronic structure during diamond synthesis. Three carbon adsorption models were constructed for comparison. Results indicated that nitrogen atoms destabilize the adsorption system and that the interaction between adatoms could not be ignored. According to the calculated interaction energies, the C-C interaction was stronger than the C-N interaction. Differences in the partial density of states (PDOSs) among the models suggested that the N-C interaction also improved catalysis to some extent, but this effect was not evident in comparison to the C-C interaction. The obtained atomic geomeCy and PDOS also indicated formation of CN compounds or graphite-like impurities if the adatom distance was too short, because they would occupy the same Ni(111)-(1×1) unit cell.