Bondarchuk Sergey V, Minaev Boris F
Department of Chemistry and Nanomaterials Science, Bogdan Khmelnitsky Cherkasy National University, blvd. Shevchenko 81, 18031 Cherkasy, Ukraine.
Phys Chem Chem Phys. 2017 Mar 1;19(9):6698-6706. doi: 10.1039/c6cp08723j.
A new ambient-pressure metastable single-bonded 3D nitrogen allotrope (TrigN) of trigonal symmetry (space group R3[combining macron]) was calculated using density functional theory (DFT). A comprehensive characterization of this material, comprising thermodynamic, elastic, and spectral (vibrational, UV-vis absorption, and nuclear magnetic resonance) properties, was performed. Using high-throughput band structure calculation, the TrigN phase was characterized as an insulator with an indirect band gap of 2.977 eV. Phonon dispersion calculations justified that this structure is vibrationally stable at ambient pressure. The calculated Raman activities at the Γ-point demonstrated a rich pattern, whereas no relatively intense transitions were observed in its IR absorption spectrum. The TrigN material is almost transparent to visible light as well as to ultraviolet A and B. The main absorption peaks appeared within the range of 50-200 nm. The electron arrangement of the nitrogen nuclei in the studied nitrogen allotrope is much denser compared to that of the molecular nitrogen, which is in agreement with the calculated magnetic shielding tensor values. Robust mechanical stability is revealed from the elastic constants calculation. Due to strong anisotropy, the values of the Young's moduli vary from 281 to 786 GPa. A huge amount of internal energy is enclosed in the TrigN material. Upon decomposition to molecular nitrogen, the energy release is expected to be 11.01 kJ g compared to the value of 10.22 kJ g for the cubic gauche form of nitrogen. The TrigN allotrope possesses unique detonation characteristics with a detonation pressure of 146.06 GPa and velocity of 15.86 km s.
利用密度泛函理论（DFT）计算出一种具有三角对称性（空间群R3[上加一横]）的新型常压亚稳单键三维氮同素异形体（TrigN）。对该材料进行了全面表征，包括热力学、弹性和光谱（振动、紫外可见吸收和核磁共振）性质。通过高通量能带结构计算，TrigN相被表征为具有2.977 eV间接带隙的绝缘体。声子色散计算表明，该结构在常压下振动稳定。在Γ点计算的拉曼活性显示出丰富的模式，而在其红外吸收光谱中未观察到相对强烈的跃迁。TrigN材料对可见光以及紫外线A和B几乎是透明的。主要吸收峰出现在50 - 200 nm范围内。与分子氮相比，所研究的氮同素异形体中氮核的电子排列更为密集，这与计算出的磁屏蔽张量值一致。弹性常数计算表明其具有强大的机械稳定性。由于强烈的各向异性，杨氏模量值在281至786 GPa之间变化。TrigN材料包含大量内能。分解为分子氮时，预计能量释放为11.01 kJ/g，而立方扭折形式的氮为10.22 kJ/g。TrigN同素异形体具有独特的爆轰特性，爆轰压力为146.06 GPa，速度为15.86 km/s。
