title: Pressure-induced chemistry in a nitrogen-hydrogen host-guest structure.
abstract: New topochemistry in simple molecular systems can be explored at high pressure. Here we examine the binary nitrogen/hydrogen system using Raman spectroscopy, synchrotron X-ray diffraction, synchrotron infrared microspectroscopy and visual observation. We find a eutectic-type binary phase diagram with two stable high-pressure van der Waals compounds, which we identify as (N2)6(H2)7 and N2(H2)2. The former represents a new type of van der Waals host-guest compound in which hydrogen molecules are contained within channels in a nitrogen lattice. This compound shows evidence for a gradual, pressure-induced change in bonding from van der Waals to ionic interactions near 50 GPa, forming an amorphous dinitrogen network containing ionized ammonia in a room-temperature analogue of the Haber-Bosch process. Hydrazine is recovered on decompression. The nitrogen-hydrogen system demonstrates the potential for new pressure-driven chemistry in high-pressure structures and the promise of tailoring molecular interactions for materials synthesis.
authors.affiliation: CEA, DAM, DIF, F-91297, Arpajon, France.
authors.forename: Dylan K
authors.initials: DK
authors.lastname: Spaulding
authors.affiliation: CEA, DAM, DIF, F-91297, Arpajon, France.
authors.forename: Gunnar
authors.initials: G
authors.lastname: Weck
authors.affiliation: CEA, DAM, DIF, F-91297, Arpajon, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Loubeyre
authors.affiliation: Institut de Minéralogie, de Physique des Matériaux, et de Cosmochimie (IMPMC), Sorbonne Universités-UPMC Université Paris 6, CNRS UMR 7590, IRD UMR 206, MNHN, 4 place Jussieu, F-75005 Paris, France.
authors.forename: Fréderic
authors.initials: F
authors.lastname: Datchi
authors.affiliation: SOLEIL, L'Orme des Merisiers, Saint-Aubin-BP48, Gif-sur-Yvette 91192, France.
authors.forename: Paul
authors.initials: P
authors.lastname: Dumas
authors.affiliation: European Synchrotron Radiation Facility, Grenoble F-38043, France.
authors.forename: Michael
authors.initials: M
authors.lastname: Hanfland