1 Scientific RepoRts | 6:25947 | DOI: 10.1038/srep25947 www.nature.com/scientificreports Diverse Chemistry of stable Hydronitrogens, and Implications for planetary and Materials sciences Guang-Rui Qian 1,* , Haiyang Niu 1,* , Chao-Hao Hu 2,3 , Artem R. oganov 4,5,1,6 , Qingfeng Zeng 6 & Huai-Ying Zhou 2 Nitrogen hydrides, e.g., ammonia (NH 3 ), hydrazine (N 2 H 4 ) and hydrazoic acid (HN 3 ), are compounds of great fundamental and applied importance. their high-pressure behavior is important because of their abundance in giant planets and because of the hopes of discovering high-energy-density materials. Here, we have performed a systematic investigation on the structural stability of N-H system in a pressure range up to 800 GPa through evolutionary structure prediction. Surprisingly, we found that high pressure stabilizes a series of previously unreported compounds with peculiar structural and electronic properties, such as the N 4 H, N 3 H, N 2 H and NH phases composed of nitrogen backbones, the N 9 H 4 phase containing two-dimensional metallic nitrogen planes and novel N 8 H, NH 2 , N 3 H 7 , NH 4 and NH 5 molecular phases. Another surprise is that NH 3 becomes thermodynamically unstable above ~460 GPa. We found that high-pressure chemistry of hydronitrogens is much more diverse than hydrocarbon chemistry at normal conditions, leading to expectations that N-H-o and N-H-o-s systems under pressure are likely to possess richer chemistry than the known organic chemistry. this, in turn, opens a possibility of nitrogen-based life at high pressure. the predicted phase diagram of the N-H system also provides a reference for synthesis of high-energy-density materials. Hydrogen is the most abundant, and nitrogen is the seventh most abundant element in the universe. Giant planets Uranus and Neptune are predominantly made of H, O, C and N. While the behavior of the H-O 1 and C-O 2 sys- tems under pressure has been investigated in some detail, the N-H system remains largely unexplored. Ammonia (NH 3 ), an important compound in many branches of science and technology, was frst proposed to exist in Uranus and Neptune by Ramsey 3 and Bernal and Mussey 4 in early 1950 s, and further discussed by Stevenson and Bundy 5,6 . It is the only stable hydronitrogen at ambient conditions, and exists in a wide range of tempera- tures and pressures. Recent studies 7–9 revealed that ammonia undergoes a series of phase transitions, including ionic disproportionation and return to non-ionic phase at megabar pressures. Ammonia is considered as a major component of the interiors of giant planets such as Uranus and Neptune under extreme pressure (up to 600 GPa) and temperature (2,000∼7,000 K) 10–14 . What has not been properly explored is the full phase stability in the N-H system, including the possibility of decomposition of ammonia; it may well be that, instead of ammonia, very diferent molecules with diferent stoichiometries are actually present in planetary interiors. All nitrogen hydrides, except ammonia, are metastable at ambient pressure. Due to the substantial energy diference between single and triple nitrogen-nitrogen bonds, nitrogen-rich hydronitrogens are potentially supe- rior high-energy-density materials. However, large-scale synthesis of these materials is still problematic. Having 1 Department of Geosciences, center for Materials by Design, and institute for Advanced computational Science, State University of New York, Stony Brook, NY 11794-2100, USA. 2 Guangxi Key Laboratory of information Materials, Guilin University of Electronic Technology, Guilin 541004, P.R. China. 3 School of Materials Science and engineering, Guilin University of Electronic Technology, Guilin 541004, P.R. China. 4 Skolkovo institute of Science and technology, Skolkovo Innovation Center, 3 Nobel St., Moscow 143026, Russia. 5 Moscow Institute of Physics and Technology, 9 Institutskiy lane, Dolgoprudny city, Moscow Region 141700, Russia. 6 international center for Materials Discovery, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, P.R. China. * These authors contributed equally to this work. Correspondence and requests for materials should be addressed to G.-R.Q. (email: iqianguangrui@gmail.com) or A.R.O. (email: artem.oganov@stonybrook.edu) Received: 08 April 2015 Accepted: 29 March 2016 Published: 19 May 2016 opeN