Bonding Properties of Aluminum Nitride at High Pressure
Bonding Properties of Aluminum Nitride at High Pressure
复制标题
氮化铝的高压结合性能
DOI：
10.1021/acs.inorgchem.7b00980
复制
发表时间：
2017-07-03
影响因子：
4.6
通讯作者：
Cui, Tian
中科院分区：
文献类型：
--
作者：
Liu, Zhao;Li, Da;Cui, Tian
探索稳定的聚合氮相的键合性质和聚合机理是我们高压研究的主要目标。建立了Al-N系压力-成分相图。在43 ~ 85 GPa压力范围内，AlN除了存在Fm（3）相外，还存在明显的N-6（6-）阴离子聚合氮链单斜相。它的能量密度高达2.75kJ·g（-1），氮的重量比接近61%，这使得它作为一种高能量密度材料具有潜在的工业应用价值。在此预测阶段的原子和电子结构的高压研究表明，N-6（6-）阴离子的形成是由氮原子的sp（2）杂化驱动的。高分子氮链中π键和σ键的共振效应是结构稳定的主要原因。由于电子从铝分子转移到高分子氮链上，在AlN 3的电子结构中存在赝能隙。Np电子与相邻原子形成π型化学键，导致π电子离域，并在高分子氮链中发生电荷转移。此外，高分子氮链中氮原子之间电荷密度分布的不均匀性是导致金属性的主要原因。
Exploring the bonding properties and polymerization mechanism of stable polymeric nitrogen phases is the main goal of our high-pressure study. The pressure versus composition phase diagram of the Al-N system is established. In addition to the known Fm (3) over barm phase of AlN, a notable monoclinic phase with N-6(6-) anion polymeric nitrogen chains for AlN3 in the pressure range from 43 to 85 GPa is predicted. Its energy density is up to 2.75 kJ.g(-1) and the weight ratio of nitrogen is nearly 61%, which make it potentially interesting for the industrial applications as a high energy density material. The high-pressure studies of atomic and electronic structures in this predicted phase reveal that the formation of N-6(6-) anion is driven by the sp(2) hybridization of nitrogen atoms. The resonance effect between alternating pi-bonds and sigma-bonds in polymeric nitrogen chains are all responsible for the structural stability. Because of the electrons transfer from aluminums to polymeric nitrogen chains, there is a pseudogap in the electronic structures of AlN3. The N_p electrons form pi-type chemical bonds with the neighboring atoms, resulting in the delocalization of pi electrons and charge transfer in polymeric nitrogen chains. Furthermore, disparities of charge density distribution between nitrogen atoms in polymeric nitrogen chains are the principal reason for the metallicity.