Polymerization of Nitrogen in Nitrogen–Fluorine Compounds under Pressure

Abstract

A wide range of polynitrogen species have attracted much attention because of their potential applications as high-energy-density materials. Until now, predicted polynitrogen was found to be negatively charged, with charge transfer from introduced atoms to nitrogen in nitrogen-bearing compounds. Using an evolutionary algorithm combined with first-principles calculations, stoichiometries and structures in nitrogen–fluorine compounds at pressures ranging from 0 to 200 GPa are investigated. In addition to two fluorine-rich compounds NF3 and NF5, two other compounds, NF and N6F, emerge with increasing pressure. N6F, as a nitrogen-rich compound, will become stable at pressures greater than 180 GPa with a positively charged nitrogen network. Above 120 GPa, the NF compound with polymeric zigzag nitrogen chains is discovered, and it is quenchable to the ambient conditions, acquiring the highest energy density of 5.38 kJ/g among reported binary covalent nitrogen compounds. These newly predicted N–F compounds are useful in understanding the chemistry of polynitrogen.

Polynitrogen clusters interaction with water: experimental and theoretical perspectives

“…During combustion and explosion reactions, they can be converted into diatomic nitrogen molecules, and released enormous amounts of energy without generating harmful waste. It is due to the fact that the exceptionally strong N≡N triple bond (946 kJ mol −1 ) in N 2 , which is much stronger than the sum of three N-N single bond (159 kJ mol −1 ) or 3/2 times of the strength of the N=N double bond (419 kJ mol −1 ) [5][6][7]. Therefore, polynitrogen clusters are considered to be clean high-energy-density materials (HEDMs) with broad applications in various fields, including aerospace [5][6][7].…”

High-Pressure Studies of Trimethylsilane Azide by Raman Scattering and Synchrotron X–ray Diffraction

“…In addition, several theoretical studies on inorganic azides indicate that the azide ions could be turned into benzene, like N 6 rings or zigzag N chains, and then forming polymeric nitrogen at sufficiently high pressure. , The high polymerization pressure in inorganic azides is caused by the linear azide ion that the hybridization of electron orbit is difficult to occur between adjacent nitrogen atoms . The extreme condition restricts the scientific study and practical application of polymeric nitrogen. − It is therefore of fundamental and practical interest to explore new strategy in forming polynitrogen at relatively low pressure.…”

Route to Stabilize Cubic Gauche Polynitrogen to Ambient Conditions via Surface Saturation by Hydrogen

“…[28][29][30][31][32][33] The first polymerized nitrogen with fully single bonding, named as cubic gauche polynitrogen (cg-N), was theoretically predicted to appear at 50 GPa, [29] and its energy density is about five times larger than that of TNT. [34] Furthermore, many kinds of polynitrogens (such as chains, [35,36] layers, [37,38] cage, [39] and polynitrogen [40,41] ) were theoretically proposed to be thermodynamically stable at high pressure. In 2004, the cg-N was successfully synthesized under the extreme conditions of 110 GPa and 2000 K. [42] Following cg-N, layered polymeric nitrogen (LP-N), [43] black phosphorus nitrogen (BP-N), [44] and hexagonal layered polymeric nitrogen (HLP-N) [45] have been synthesized at the pressures of 120 GPa, 150 GPa, and 180 GPa, respectively.…”