title: Diverse Chemistry of Stable Hydronitrogens, and Implications for Planetary and Materials Sciences.
abstract: Nitrogen hydrides, e.g., ammonia (NH3), hydrazine (N2H4) and hydrazoic acid (HN3), 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 N4H, N3H, N2H and NH phases composed of nitrogen backbones, the N9H4 phase containing two-dimensional metallic nitrogen planes and novel N8H, NH2, N3H7, NH4 and NH5 molecular phases. Another surprise is that NH3 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.
authors.affiliation: 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.
authors.forename: Guang-Rui
authors.initials: GR
authors.lastname: Qian
authors.affiliation: 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.
authors.forename: Haiyang
authors.initials: H
authors.lastname: Niu
authors.affiliation: Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004, P.R. China.|School of Materials Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, P.R. China.
authors.forename: Chao-Hao
authors.initials: CH
authors.lastname: Hu
authors.affiliation: Skolkovo Institute of Science and Technology, Skolkovo Innovation Center, 3 Nobel St., Moscow 143026, Russia.|Moscow Institute of Physics and Technology, 9 Institutskiy lane, Dolgoprudny city, Moscow Region 141700, Russia.|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.|International Center for Materials Discovery, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, P.R. China.
authors.forename: Artem R
authors.initials: AR
authors.lastname: Oganov
authors.affiliation: International Center for Materials Discovery, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, P.R. China.
authors.forename: Qingfeng
authors.initials: Q
authors.lastname: Zeng
authors.affiliation: Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004, P.R. China.
authors.forename: Huai-Ying
authors.initials: HY
authors.lastname: Zhou