High Pressure and High Temperature Synthesis of the Iron Pernitride FeN2
At a Glance
Section titled “At a Glance”| Metadata | Details |
|---|---|
| Publication Date | 2018-03-05 |
| Journal | Inorganic Chemistry |
| Authors | Dominique Laniel, Agnès Dewaele, Gastón Garbarino |
| Institutions | European Synchrotron Radiation Facility, Commissariat à l’Énergie Atomique et aux Énergies Alternatives |
| Citations | 61 |
Abstract
Section titled “Abstract”The high pressure chemistry of transition metals and nitrogen was recently discovered to be richer than previously thought, due to the synthesis of several transition metal pernitrides. Here, we explore the pressure-temperature domain of iron with an excess of nitrogen up to 91 GPa and 2200 K. Above 72 GPa and 2200 K, the iron pernitride FeN<sub>2</sub> is produced in a laser-heated diamond anvil cell. This iron-nitrogen compound is the first with a N/Fe ratio greater than 1. The FeN<sub>2</sub> samples were characterized from the maximum observed pressure down to ambient conditions by powder X-ray diffraction and Raman spectroscopy measurements. The crystal structure of FeN<sub>2</sub> is resolved to be a Pnnm marcasite structure, analogously to other transition metal pernitrides. On the basis of the lattice’s axial ratios and the recorded N-N vibrational modes of FeN<sub>2</sub>, a bond order of 1.5 for the nitrogen dimer is suggested. The bulk modulus of the iron pernitride is determined to be of K<sub>0</sub> = 344(13) GPa, corresponding to an astounding increase of about 208% from pure iron. Upon decompression to ambient conditions, a partial structural phase transition to the theoretically predicted R3̅ m FeN<sub>2</sub> is detected.