Li Dongxu, Oganov Artem R, Dong Xiao, Zhou Xiang-Feng, Zhu Qiang, Qian Guangrui, Dong Huafeng
College of Materials Science and Engineering, Huaqiao University, Xiamen, 361021 P.R. China.
Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel St., Moscow 143026, Russia.
Sci Rep. 2015 Nov 17;5:16311. doi: 10.1038/srep16311.
Nitrogen oxides are textbook class of molecular compounds, with extensive industrial applications. Nitrogen and oxygen are also among the most abundant elements in the universe. We explore the N-O system at 0 K and up to 500 GPa though ab initio evolutionary simulations. Results show that two phase transformations of stable molecular NO2 occur at 7 and 64 GPa, and followed by decomposition of NO2 at 91 GPa. All of the NO(+)NO3(-) structures are found to be metastable at T = 0 K, so experimentally reported ionic NO(+)NO3(-) is either metastable or stabilized by temperature. N2O5 becomes stable at 9 GPa, and transforms from P-1 to C2/c structure at 51 GPa. NO becomes thermodynamically stable at 198 GPa. This polymeric phase is superconducting (Tc = 2.0 K) and contains a -N-N- backbone.
氮氧化物是典型的分子化合物类别，具有广泛的工业应用。氮和氧也是宇宙中最丰富的元素之一。我们通过从头算演化模拟研究了0 K至500 GPa压力下的N - O体系。结果表明，稳定的分子NO₂在7 GPa和64 GPa时发生两次相变，然后在91 GPa时NO₂分解。所有NO⁺NO₃⁻结构在T = 0 K时均为亚稳态，因此实验报道的离子型NO⁺NO₃⁻要么是亚稳态的，要么是由温度稳定的。N₂O₅在9 GPa时变得稳定，并在51 GPa时从P - 1结构转变为C2/c结构。NO在198 GPa时热力学稳定。这种聚合相是超导的（Tc = 2.0 K），并且包含 -N - N-主链。
